Zoology

Zoology
Ayatollah al-Uzma Muhammad Reza Nekounam (may his sanctity be preserved)

Preface

Human beings, endowed with a unique station that lies between beauty and majesty, can—by voluntary and conscious endeavour—attain a state where the involuntary language of the heart and inner self perceives other phenomena and coexists with them in harmony and dialogue, receiving them graciously. This combined station empowers humans with the capacity to descend and ascend simultaneously, ensuring that their status is neither fixed nor confined to any particular rank or direction.

Humans, whose outward nature exhibits gentleness and sociability, naturally abhor hatred and estrangement. They are inherently social beings who not only compassionately cherish all things but can also form attachments and live harmoniously with any phenomenon. Through the power of relational capacity and collective association, a human can grow accustomed to, and fond of, any object or being over time, becoming so intimately united with its qualities that separation becomes painful and difficult. This intimacy is founded upon sincerity and entails commitment. Human marriage, for example, is grounded in sincerity, dowry, and responsibility. In contrast, mere cohabitation lacks this commitment. The contemporary world, dominated by colonialism and opposition to divine law, has attacked this sacred institution.

Certain advanced animals, such as birds capable of flight, do not merely cohabit; the female seeks to marry the strongest and most affectionate male—one who is committed and capable of fulfilling his duties towards offspring. She tests and judges the male’s suitability to ensure healthy and secure procreation, thus exhibiting order, health, and power even in their lustful behaviours.

Human intimacy, in contrast, is a heartfelt and binding affection—an interaction that enriches both parties. Both the familiar phenomenon and the human are mutually developed and refined, while the human ultimately benefits spiritually and materially from this relationship. The capacity for commitment and empathy in humans underlies the understanding of the musical language of animals. In my youth, at the suggestion of my spiritual mentor, I devoted time to bonding with animals to perceive their language through closeness and companionship.

During this period, I clearly perceived that all phenomena, including plants and animals, possess degrees of spiritual guardianship (wilayah). No phenomenon exists without an aspect of guardianship deriving from the Divine, whose source is divine lordship (rububiyyah). This divine lordship grants perfection and capacity to every entity. The life of the universe is thus underpinned by guardianship, and even the concept of unity (tawhid) is measured by it. The love of any phenomenon corresponds to the extent of its guardianship. Guardianship is the essence and inner reality of every entity.

Every phenomenon, according to its degree of guardianship, has closeness, grace, and divine beauty. There is no entity devoid of unique and hierarchical beauty, though humans may not perceive it. The greater the beauty, the stronger and more profound the general guardianship it enjoys, necessitating acceptance of special guardianship. The defence of each entity is a manifestation of its guardianship, which constitutes its unity.

The higher levels of guardianship are manifest in prophets, messengers, imams, caliphs, and absolute divine saints, who embody the full perfection of the perfect human. Each flower, thorn, plant, fire, ash, rain, sea, and human embodies power, nobility, zeal, wrath, health, judgement, and obligation according to its guardianship. The extent and measure of each entity’s guardianship equate to its intrinsic grace.

Each phenomenon carries its own laws and duties according to its governance, and no animal is devoid of divine command, guardianship, and guidance. Understanding a phenomenon entails understanding its laws, guardianship, and proximity to the Divine, revealing its degree of awareness, will, and love. Such guardianship is a sovereignty bestowing unique and exclusive perfections.

It is not only divine scholars who possess guardianship over humans; animals and plants also hold guardianship over one another. Some creatures enjoy special guardianship in addition to general guardianship. Every phenomenon, according to its special guardianship, has a distinct mention and association with a particular Imam, seeking closeness to him. Not all creatures can draw near to Imam Ali (peace be upon him), and each individual must find their own special Imam.

Humans remain healthy only by avoiding those without special guardianship, who, despite lacking malevolence, are unworthy of affection. Those with special guardianship attract healthy hearts. Among animals, those with authority, beauty, and voice possess special guardianship—pigeons, for example. Lions, tigers, and leopards have special guardianship and, consequently, authority, beauty, and grace; even their ferocity arises from love.

The nature of some animals resonates and aligns with their guardians. Conversely, pigs and monkeys lack special guardianship. Those trapped in animalistic nature and traits, even if outwardly beautiful and possessing general guardianship, lack true charm. They lead observers to lust rather than honour, lacking dignity and respect. Those who reject guardianship are ranked lower than animals without special guardianship. Imam Ja’far al-Sadiq (peace be upon him) remarked to Abu Basir about people who only wail and lament without performing pilgrimage, entering the sacred precinct of the Kaaba as animals do.

Some humans have been transformed by divine punishment into the animal state, losing the will to survive and dying shortly thereafter. Likewise, animals manifesting by prophetic miracle do not possess natural longevity and perish if not killed. An animal born and raised naturally in the physical world possesses natural survival instincts.

God’s Essence: Doubt, Relativity, and Ontological Self-Foundation

Divine essence possesses degrees of doubt and relativity, and according to their own epistemology, awareness, and inherent capability within the worldly realm (nasut), they embody conditions of necessity, transformation, and mutability. Thus, the proximity or remoteness from the divine is not exclusive to human beings. Nonetheless, the ultimate perfect human will, by virtue of authority and purpose, actualise every phenomenon. The collective and perfect human leaves no one astray on the path and provides access and connection to all.

Praise be to God.

Chapter One: Generalities of Animals

It is estimated that there are approximately seven million distinct animal species worldwide. Of these, one and a half million species have been identified in biology, with insects constituting one million of that number. Each of these animals possesses unique characteristics that differentiate them from other living beings. This is scientific fact; however, we assert that each individual animal is a unique phenomenon and a distinct species, indeed singular. Regarding humans, we have stated that each individual is not merely a single type but embodies various types according to their collective rank.

Generally, all animals have the ability to move at least during certain stages of their lives. Except for a few exceptions such as sponges, animals have bodies composed of various tissues; for example, muscular tissue, which can contract and control movement.

The largest animal ever to have lived on Earth is the blue whale, weighing 190 tonnes and measuring 33 metres in length. The largest current land animal is the African bush elephant, weighing 12 tonnes and exceeding 10 metres in length. Historically, the largest terrestrial animal was the dinosaur Argentinosaurus, approximately 30 to 40 metres long and estimated to weigh about 70 tonnes. In contrast, unicellular animals, such as certain mucus-dwelling parasitic species, represent the smallest animal forms, with some growing only up to 8 micrometres.

Animals are divided into two primary subgroups: vertebrates and invertebrates.

• Vertebrates: Birds, mammals, amphibians, reptiles, and fish.
• Invertebrates: Molluscs, bivalves, octopuses, coelenterates (corals), echinoderms, sea stars, sea urchins, sea cucumbers, tunicates, arthropods, insects, spiders, scorpions, crabs, shrimps, mantis shrimps, worms, and sponges—each comprising various categories.

Vertebrates

An animal is considered a vertebrate if it possesses a backbone to protect its spinal cord muscles. Vertebrates include fish, amphibians, reptiles, birds, and mammals. The backbone comprises a series of small and large bones called vertebrae, connected by cord-like ligaments that provide both flexibility and strength by firmly holding the back muscles in place. The spinal cord passes through the central canal of the vertebrae, protected from damage. Some primitive fish, sharks, and rays have cartilage instead of a bony backbone—a strong but flexible rubber-like structure.

Vertebrates constitute a vast proportion of bony animals and include the largest and most intelligent animals globally. This subgroup encompasses over 64,000 species, divided into five classes.

Vertebrates have not equally succeeded in colonising terrestrial environments. Most amphibians remain near water bodies to reproduce. Most reptiles are confined to tropical and temperate regions. Mammals and birds show broader distribution and adaptability.

Vertebrate bodies consist of a head, trunk, and tail, with internal skeletons and brains enclosed in skulls. They develop an initial spinal cord (notochord) in the embryo and possess a spinal cord and backbone in adulthood. Vertebrates have either pharyngeal gills or lungs and a closed circulatory system. Their hearts pump blood containing white blood cells and haemoglobin within red blood cells. They also possess lymphatic systems, livers, and advanced internal glands. This subgroup includes humans and other animals of significant importance, making them particularly interesting and noteworthy.

Psychologically, vertebrates exhibit higher intelligence compared to invertebrates. Non-psychological characteristics include more complex organisms with advanced brains and nervous systems, comprising only 2% of all animals (compared to 98% invertebrates). Vertebrates tend to be larger and more mobile, whereas invertebrates are generally smaller and slower.

The Amphibian Branch

Amphibians, a class of vertebrates, consist of about 2,500 species. They are cold-blooded and experience two distinct life stages, undergoing complete metamorphosis. Their juvenile phase is aquatic with fins and gills for respiration, while the adult phase includes limbs and lungs for life on land and in water. Amphibians are egg-layers and cold-blooded. Frogs and toads are examples.

Amphibians lack teeth and claws but possess an effective defence system. They are small, smooth-skinned, and generally inactive during the day. Some, like chameleons, use camouflage for survival.

Modern amphibians differ greatly from those existing 75 million years ago, whose ancestors likely appeared in the late Paleozoic era. Their small bodies adapted to marginal habitats, exploiting resources unused by larger relatives, possibly avoiding competition. Large amphibians gradually became extinct by the late Triassic.

Amphibians are divided into three subclasses: Gymnophiona, Caudata, and Anura. Only the latter survives, including all contemporary amphibians like frogs, salamanders, and newts.

Key amphibian features include:

• Bare, moist skin rich in mucous glands without scales.
• Two pairs of limbs for walking or crawling, with 4–5 digits, sometimes webbed (e.g., frogs).
• Fully bony skeletons without ribs.
• Hearts with two separate atria and one ventricle, with incomplete double circulation.
• Respiration via gills, lungs, skin, and oral mucosa.
• Brains with two hemispheres, developed olfactory lobes, and ten pairs of cranial nerves.
• Cold-blooded physiology.
• Internal or external fertilisation; mostly oviparous.

Physiological Challenges of Terrestrial Life

Animals face significant physiological challenges surviving on land compared to aquatic environments, mainly due to relatively scarce water. Four key challenges unique to terrestrial life include:

1. Energy expenditure in seeking water, which is less accessible.
2. Wide temperature fluctuations requiring energy for thermoregulation.
3. Fighting gravity, which increases energy use, whereas water buoyancy partly counteracts gravity.
4. Greater energy investment in obtaining food due to lower animal density and diversity compared to aquatic habitats.

Amphibians possess gills for aquatic respiration, and their moist skin can absorb dissolved oxygen. They also have lungs and air sacs to assist breathing on land.

These points describe physiological rather than psychological traits.

The Fish Branch

Fish are cold-blooded aquatic animals that swim using fins. Pectoral fins assist in turning; the tail fin is used for swift movement. Most fish have scales that cover their slippery skin. They breathe through gills located on both sides of their heads.

One litre of air contains approximately 210 cm³ of oxygen, whereas one litre of freshwater contains only about 8 cm³. Water is 777 times denser and 100 times more viscous than air, and oxygen diffusion in air is 10,000 times faster than in water. Therefore, lungs alone are inefficient for aquatic life, necessitating fish to have gills.

In bony fish, gills reside in a branched chamber covered by a bony plate, which regulates water pressure in the gills, allowing fish to breathe without constant movement. A membrane prevents water from escaping the gills.

Air-breathing fish fall into two categories: obligate air breathers, which must breathe air or die (e.g., African lungfish), and facultative air breathers, which breathe air only when necessary (e.g., catfish).

Fish reproduce via egg-laying in water, with most species oviparous. Eggs are laid suspended in water or attached to surfaces. Mortality among eggs and fry is high; only a few reach maturity.

Fish reproductive organs include testes and ovaries. Males produce milt (sperm fluid), while females produce eggs in ovaries released externally. Fertilisation may be internal or external. Some fish retain fertilised eggs internally until birth, termed viviparity. Certain species, including some sharks and ornamental fish, are viviparous. Some species are hermaphroditic, possessing both male and female reproductive organs, although self-fertilisation is rare.

Larvae are born with a yolk sac for nutrition and undergo metamorphosis into juveniles, during which time parental care is sometimes observed.

Fish are aquatic, gill-breathing, skull-bearing vertebrates without fingers or toes. Most are cold-blooded, allowing body temperature to match ambient water. Some large, fast swimmers, like the great white shark and tuna, maintain slightly higher internal temperatures.

Fish inhabit nearly all aquatic environments, from mountain streams to the ocean’s depths. There are approximately 33,100 identified species, the most extensive group among vertebrates.

Fish represent a significant human food source, with fishing as a primary livelihood. Some fish are captured for aquaria or as pets. Historically, fish held divine significance in various cultures, symbolising religious or artistic motifs.

Why have fish held divine or symbolic religious roles in some ancient cultures?
Since ancient times, rural Indian communities have revered certain fish species as symbols of divine power, protecting them in temple ponds. Fish are considered sacred due to their association with the god Vishnu, whose first earthly incarnation was as a fish.

Many Hindu groups adhere to a strict vegetarian diet; therefore, most of them do not consume fish. However, a fish plays a fundamental role in a key creation myth within the Vaishnavism sect of Hinduism. Vishnu, the supreme deity of Vaishnavism, has had ten avatars or incarnations on Earth. His first avatar, Matsya, is often depicted as a fish or a half-human, half-fish form. The legend narrates that Matsya appeared as a small fish to Manu, the archetypal ancient man or the first human, and requested his protection. In return, Matsya promised to assist him in surviving a great flood. Matsya grew under Manu’s care, and eventually, Manu released him into the ocean. When the legendary deluge came, Matsya guided Manu’s boat to a safe location. After the flood receded, Manu realised he was the sole survivor and was responsible for repopulating humanity.

In Buddhism, the Ashtamangala (Eight Auspicious Symbols) include two golden fish as one of the sacred emblems. The symbol of two fish signifies good fortune, fertility, and salvation. The golden fish represent the fearless and unhindered state of floating in the ocean of Samsara—the cyclic existence of birth and rebirth. These fish symbolise the fearless nature of all beings as they navigate the turbulent ocean of suffering brought about by endless reincarnations. According to legend, these symbols were gifts bestowed upon the Buddha by the gods after his enlightenment. Initially, the golden fish were associated with the rivers Ganges or Yamuna, sacred rivers of India.

In Jewish tradition, the fish symbol also plays an important role. Many allegories in the Torah relate to the Jewish people. Due to their prolific fertility—fish typically lay numerous eggs—the fish symbolises fertility and luck. Sephardic Jews use the fish symbol as a talisman against the evil eye. Fish is a traditional food for Rosh Hashanah (the Jewish New Year) because it is customary to eat foods that signify good fortune for the coming year. For example, Gefilte fish (a type of fish dumpling) is commonly served by Ashkenazi Jews.

The Greeks, Romans, and many pre-Christian polytheistic religions also utilised the fish symbol. In polytheistic beliefs, Ictis—the son of the sea goddess Atargatis—is known by various names including Tirtagata, Aphrodite, Plagia, or Delphin. These names, in some languages, mean “womb” and in others “dolphin.” Before Christianity, the fish symbol was associated with mother goddesses and represented “womb” and fertility. The Celts and northern European polytheists believed this symbol was connected to fertility, childbirth, and the natural power of women. In certain non-Christian beliefs, fish symbolise reincarnation and life force.

The fish of Jesus, or Ictis (symbolised by two intersecting arcs), is perhaps the second most important symbol in Christianity. Early Christians used the fish as a secret code to identify meeting places, tombs, and fellow believers. According to legend, when an early Christian met a stranger, they would draw half of the Ictis symbol (a curved line) on the ground; if the stranger completed the symbol, they both knew they were Christians. There has been much debate about why the fish was chosen as a Christian symbol, but fish are prominent in the Gospels. Several apostles were fishermen who became “fishers of men,” and Jesus famously fed five thousand people with five small loaves and two fish.

In Arabic, the letter “Nūn” (ن) represents a fish. According to the Holy Qur’an, the fish symbolises eternal life and scholars. Like Jews, Muslims are instructed to consume only scaled fish, not those without scales. In Islamic tradition, Khidr is known as Moses’ guide. He is often depicted riding on a fish across the “river of life.” In one narrative, Moses claims to be the most knowledgeable man on Earth, but God corrects him and commands him to catch a salted fish and follow Khidr; when the fish comes back to life, Moses will meet his guide.

Various fish species account for more than half of all vertebrate species. There are nearly 28,000 recognised fish species: about 27,000 bony fishes, 970 cartilaginous fishes—including sharks and rays—and around 108 species of jawless and sucker fishes. One-third of these species are classified into nine large families, ranked from largest to smallest: Cyprinidae, Cichlidae, Carassidae, Catostomidae, Characidae, Percidae, Serranidae, Labridae, and Scorpaenidae. The total number of extant fish species likely exceeds 32,500.

Many aquatic creatures commonly referred to as fish are no longer classified as such. Examples include jellyfish, starfish, crustaceans, molluscs, and sea anemones. Historically, zoologists did not distinguish clearly among aquatic animals, and animals such as crocodiles, hippopotamuses, amphibians, whales, porpoises, and many marine invertebrates were categorised as fish. However, modern science classifies all mammals, including cetaceans like whales and dolphins, separately from fish.

Some traits mentioned about fish have exceptions. For example, tuna, swordfish, sailfish, and certain sharks are known to be warm-blooded or possess characteristics akin to warm-blooded animals. They can internally raise their body temperature to be warmer than the surrounding water. The body shape and swimming methods of fish vary widely. For instance, tunas, salmons, and billfish can swim 10 to 20 times their body length per second, whereas rays and eels swim less than half a body length per second. Many freshwater fish can extract oxygen from the air as well as water through specialised structures. Lungfish, like tetrapods, possess a pair of lungs. Gouramis have a labyrinth organ functioning similarly to lungs, enabling them to breathe air. Some catfish absorb oxygen through their skin or gut. Certain fish species spend more time on land, such as the mudskipper, which forages on land and only retreats underwater for protection. Some catfish live underground, in subterranean water tables and water-saturated leaf litter.

Fish navigate using distinctive environmental cues and internal maps of their surroundings, considering specific features of each area. Experiments on fish in mazes have demonstrated their use of spatial memory and visual cues to distinguish differences. Research by William Tavolga has found evidence that fish respond to pain and fear. For example, toadfish subjected to electric shocks emit distress sounds and display similar responses upon encountering electrodes.

In 2003, Scottish scientists at the University of Edinburgh’s Roslin Institute concluded that rainbow trout exhibit pain-related behaviour akin to other animals. In this experiment, bee venom and acetic acid were injected into the fish’s lips, causing them to rub their lips against surfaces and shake their bodies—behaviours similar to those of mammals in pain. The neural signals involved were also comparable to those in humans.

James D. Rose from the University of Wyoming criticised these studies, arguing that they do not prove that fish experience conscious pain akin to humans, particularly as fish brains differ significantly from human brains. Rose contended that the fish’s behaviour might not be voluntary or conscious but could have other explanations. A year earlier, Rose had published findings asserting that fish cannot feel pain due to the absence of a neocortex. Animal behaviourist Temple Grandin countered, arguing that fish might have conscious pain awareness despite lacking a neocortex, as different species use various brain regions for similar functions. The neocortex is part of the cerebral cortex responsible in mammals for sensory processing, motor commands, spatial decision-making, self-awareness, and language.

Vision is highly important for most fish. The eye structure of fish is broadly similar to other vertebrates. Fish inhabiting deep and dark waters tend to have larger eyes than those in shallow and well-lit environments. Most fish have spherical lenses that move within the eye to focus on objects at varying distances. Despite water’s opacity and light refraction, many fish see well. Experiments show that fish living in shallow waters generally have colour vision.

Hearing is another crucial sense for most fish species, although the ability to localise sound sources underwater is diminished compared to air, due to the slower speed of sound. Underwater hearing relies on bone conduction, and localisation appears to be based on differences in amplitude perceived via bone conduction.

The olfactory system, including the olfactory organs and bulbs, is vital for acquiring environmental information and plays a direct role in social behaviour, foraging, mating, and predator avoidance. The direct connection between olfactory organs and the external environment makes them vulnerable to damage from pollutants, heavy metals, and other contaminants; however, fish bodies are designed to regenerate these structures rapidly. For example, zebra fish can regenerate even damaged neurons. Olfactory organs are particularly advanced in sharks, some of which can detect the smell of blood from up to half a kilometre away and determine the direction of the scent by timing the signals received in each nostril. Thus, the olfactory abilities of fish are comparable to those of terrestrial mammals such as rodents.

Electric Receivers in Fish and Their Sensory Capabilities

Electric receivers enable fish to perceive the electric fields and currents surrounding them. Some species — such as catfish, sharks, and electric eels — possess organs that allow them to detect weak electric potentials as low as millivolts. Other fish — for example, the South American knifefish — generate weak electric currents, which they utilise for navigation and communication. Sharks, particularly the hammerhead shark, use these organs to locate their prey. The shark’s electric sensing system is considered the most advanced among all living creatures. It can identify prey hidden beneath the sand by generating an electric field. Oceanic currents moving through the Earth’s magnetic field create electric fields that sharks likely use for navigation. Some fish — like the electric catfish — navigate murky waters by detecting nearby electric fields. These fish discern factors such as shape, size, distance, speed, and conductivity of objects by analysing spectral variations and amplitude oscillations. They can also determine species, age, and social hierarchy through these electric fields. Fish living in saline waters can detect changes in electric fields as subtle as 5 nV/cm. Magnetic receivers enable animals to orient themselves using the Earth’s magnetic field. In 1988, scientists discovered magnetised iron in the skull of the sockeye salmon, which assists in magnetic detection.

The Immune System of Fish

The immune system of fish is less advanced than that of mammals and consists of two main components: defence against external invasion and control of internal pathogens. Upon recognising a pathogen, fish initiate coordinated responses to resist it. Initially, entry points are blocked to prevent further invasion. Damaged cells produce histamine, causing inflammation near the entry points and attracting blood cells. White blood cells accumulate in the area, engulf foreign bodies, and transport them to the spleen and kidneys for quarantine or elimination. Environmental conditions affect the immune efficiency of fish; cold water slows immune responses, prompting infected fish to migrate towards warmer regions.

Fish Welfare and Conservation Efforts

Animal rights advocates have increasingly drawn global attention to the potential suffering caused to fish by fishing practices. Consequently, certain fishing methods have been prohibited in some countries, such as Germany. The UK also criminalises mistreatment of fish and issues penalties accordingly. In 2006, the International Union for Conservation of Nature (IUCN) published a Red List of threatened species, including 1,173 fish species at risk of extinction, such as the Atlantic cod, great white shark, sawfish, and sturgeon. Overfishing, defined as harvesting fish in quantities so large that the adult population cannot recover, often employs large-scale methods that endanger marine ecosystems and numerous aquatic species.

Threats to Fish Survival

Major concerns for fish survival include habitat destruction or damage, water pollution, and dam construction.

Physiological Differences and Thermoregulation in Fish

One notable physiological difference is encephalisation (brain enlargement): warm-blooded animals — such as birds and mammals — have brains approximately ten times larger than cold-blooded animals like reptiles, amphibians, and most fish. For over 50 years, scientists have known that not all fish are cold-blooded. Some shark and tuna species — for example, the great white shark and Atlantic bluefin tuna — have evolved the ability to warm certain body parts, such as muscles, eyes, and brain. Approximately 35 fish species — less than 1% of described fish species — possess this capacity, allowing them to maintain body temperatures above that of the surrounding water. The evolutionary rationale for this ability remained a mystery until recently. Some scientists proposed that being warm-blooded allows faster swimming, as warmer muscles generally exert greater force. Others suggested it enables survival across a broader temperature range, potentially mitigating effects of oceanic climate change.

An international team of marine biologists investigated why some fish are warm-blooded while most are not. Their research demonstrated that the ability to warm the body provides a competitive advantage — allowing faster swimming than cold-blooded relatives. However, these findings do not necessarily imply better adaptability to ocean temperature changes caused by climate change.

Reproductive Strategies: Oviparity vs. Viviparity

A pertinent question is how oviparity (egg-laying) versus viviparity (live-bearing) influences psychological and evolutionary outcomes. Successful reproduction demands more than species continuity; an ideal reproductive system also aims for efficiency. Two main systems dominate: oviparity and viviparity with placental connection. Oviparity is inefficient, involving high mortality rates and limiting offspring size, though it imposes fewer physiological demands on the mother. Viviparity allows much larger embryo growth, offers excellent protection, and is highly efficient but involves significant physiological strain on the mother to prevent immunological rejection of the embryo and to maintain nutrient supply and waste removal. In viviparity, the offspring develop within the mother, ensuring better nutrition, proper growth, and higher survival chances. However, viviparous species generally have longer maturation periods and produce fewer offspring. It appears that marsupials have reached a reasonable compromise by producing underdeveloped young at an early embryonic stage, without placental attachment, followed by continuous feeding and protection.

Cnidarians (e.g., Hydra)

These animals use their stinging arms, known as nematocysts, to capture prey. The nematocyst-bearing arms are thrown toward the prey, and upon contact, the prey becomes paralysed. Subsequently, the same arms bring the food into the digestive sac where digestion occurs, and waste and undigested materials are expelled through the mouth. Under favourable conditions, Hydra reproduces asexually via budding; otherwise, sexual reproduction occurs. Hydra, moss animals, and spirogyra are organisms capable of both sexual and asexual reproduction. Some biologists suggest that Hydra may be biologically immortal, never aging, although this view remains contested. These animals lack a central nervous system and do not have a clear distinction between central and peripheral nervous systems; instead, their nervous system consists solely of a nerve net.

The body of coelenterates (Cnidarians) is sac-like, communicating with the external environment via a single opening which serves both as mouth and anus. The tentacles surrounding the mouth move water and capture food, fulfilling the organism’s nutritional needs. Some of these tentacles bear stinging cells capable of secreting a paralysing toxin, which immobilises prey to be consumed as food.

The lifespan of these organisms varies; for example, sea anemones can live for hundreds of years, whereas sea anemone shrimps typically live about four months. Coelenterates exist in two distinct forms: the polyp and the medusa. Polyps have a cylindrical form and attach to the seabed by a base, whereas medusae are umbrella-shaped with the mouth located on the concave underside at the end of a narrow tube called the manubrium, with tentacles around the edge of the bell.

What Psychological Traits Are Associated with Longevity?

Using data from 538 captive chimpanzees (Pan troglodytes), a study investigated whether individual personality dimensions—agreeableness, conscientiousness, dominance, extraversion, neuroticism, and openness—correlate with lifespan. These traits represent characteristics of slow life-history strategies, especially relevant for mammals with relatively long lifespans. Researchers found that higher agreeableness correlated with longer life in males, while weaker evidence suggested that greater openness was linked to longevity in females. The results unify findings from human and non-human primate survival studies, indicating that in males, the evolution of reduced protective effects of aggression and preference for high-quality social bonds have been favoured.

Longevity is a crucial factor in enhancing fitness, as animals with longer lifespans have more opportunities to reproduce. Previous research in humans and other animals demonstrates associations between certain personality traits and increased longevity. However, few studies have been sufficiently large to examine all major personality traits across both sexes within a species.

To assess the impact of personality on longevity, another study evaluated personality traits among centenarians. Participants included 70 cognitively healthy Japanese individuals aged 100 to 106 years and 1,812 older adults aged 60 to 84 years residing in Tokyo. The NEO Five-Factor Inventory was used to assess the “Big Five” personality traits: agreeableness, conscientiousness, dominance, extraversion, neuroticism, and openness. Results showed that compared to controls, openness was higher in both male and female centenarians, while female centenarians exhibited greater conscientiousness and extraversion. These findings suggest that high scores in specific personality traits—namely conscientiousness, extraversion, and openness—are associated with increased longevity.

Phylum Mollusca

Molluscs constitute the third-largest animal phylum. Their morphology is highly diverse, characterised by a chitinous rasping organ called a radula, and bilateral symmetry that is either fully or partially lost due to segmentation. Their bodies are protected by a calcareous shell secreted by the mantle. Mollusca is a highly diverse and successful phylum that includes animals such as octopuses, snails, and squids. Molluscs have been important to humans for centuries as sources of food and pearls. Some molluscs, such as the blue-ringed octopus, possess venom potent enough to be fatal.

Most molluscs have an open circulatory system, wherein internal organs lie within a blood-filled cavity rather than being enclosed by numerous blood vessels. Excretion is performed via two kidneys. Molluscs are dioecious, with internal or external fertilisation. Their nervous system comprises cerebral, lateral, and pedal ganglia. Sensory organs such as eyes and tentacles are also present.

Molluscs inhabit marine, freshwater, and terrestrial environments, comprising approximately 50,000 species divided into classes including:

• Polyplacophora (chitons): marine, head reduced, eyeless, without tentacles; about 700 species.
• Gastropoda: marine, freshwater, or terrestrial snails with shells, typically possessing one or two pairs of tentacles and eyes; approximately 35,000 species.
• Scaphopoda: marine, tubular shells open at both ends; around 200 species.
• Bivalvia: marine or freshwater bivalves with laterally compressed shells hinged dorsally; about 12,000 species.
• Cephalopoda: squids and octopuses, marine with tentacles surrounding the head, shells either internal or reduced; about 500 species.

Phylum Porifera (Sponges)

Sponges are mostly marine, with some freshwater species. They are sessile in adulthood and often form colonies. Feeding occurs through a canal system lined by collar cells and flagellated cells. They lack nerve cells and comprise roughly 6,500 species. Classes include calcareous sponges, glass sponges, and horny sponges.

Phylum Echinodermata

Echinoderms are a large group of marine invertebrates distinct in body structure from other invertebrates. Their bodies are covered with calcareous plates and spines, displaying bilateral or often pentaradial symmetry. Some are sessile; others are free-living. Echinoderms possess a water vascular system serving circulatory, respiratory, and excretory functions, markedly differing from other invertebrates.

Echinoderms are the only invertebrates with five-part body organisation, possessing a white, hard exoskeleton potentially bearing spines. They move using hundreds of fluid-filled tube feet. Examples include brittle stars, starfish, sea urchins, and sea cucumbers. Most inhabit shallow waters, though some delicate starfish live at depths up to 7,620 metres.

Echinoderms are the closest invertebrate relatives to vertebrates. Their internal skeleton consists of multiple plates covered externally by a thin layer, giving the appearance of an exoskeleton.

There are approximately 6,500 species distributed worldwide. Most starfish are carnivorous, though some consume small plants or detritus. The common Atlantic starfish can pry open mollusc shells with a forceful stomach extension and consume the internal soft tissues. Starfish generally have five arms, though some species have up to fifty.

If an arm is severed, starfish and brittle stars can regenerate it. Wounds heal rapidly, and full regeneration occurs within weeks. In most species, the main body regenerates the lost arm, while in others, the detached arm can grow into a complete new organism. Some species use this ability for reproduction by deliberately detaching an arm that subsequently regenerates a new body.

The crown-of-thorns starfish is heavily armed with rows of long spines and feeds on coral polyps by extruding its stomach over them and absorbing the digested material. In parts of the Great Barrier Reef, populations of these starfish have significantly increased, causing substantial coral damage.

Phylum Arthropoda

Arthropods are a large phylum of invertebrates including insects, arachnids, myriapods, and crustaceans. They possess a hard, segmented exoskeleton with paired jointed appendages. The body cavity is small and lacks cilia. Arthropods have a hardened cuticle and an exoskeleton made of chitin. Each body segment bears paired jointed appendages with various functions. They have one pair of antennae and at least one pair of compound lateral eyes with independent photoreceptor units.

Their adaptability and efficiency have made arthropods the most species-rich animal phylum, occupying diverse habitats. Over one million species have been identified, representing approximately 80% of all known living animal species. Arthropods vary greatly in size, from tiny plankton to several metres long.

Tetrapods also possess segmented, jointed bodies but differ from arthropods as vertebrates have internal skeletons, while arthropods have external skeletons often with shells or carapaces. Key arthropod characteristics include:

1. Segmented, jointed bodies.
2. External skeleton made of chitin.
3. Some joints with paired appendages serving various functions.
4. Open circulatory system with a heart and a dorsal vessel.
5. Nervous system comprising a brain connected to a ventral nerve cord with ganglia.
6. Digestive tract with ectodermal anterior and posterior parts and an endodermal midgut.

The primary mode of reproduction is sexual, involving distinct males and females with notable sexual dimorphism in many species, facilitating easy sex identification. Secondary reproductive methods such as parthenogenesis (asexual reproduction without male gametes) also occur in some species, either facultatively (e.g., honeybees) or obligatorily (e.g., some wasps and aphids).

Insects

Insects constitute the largest group within arthropods. They are characterised by an external skeleton and segmented bodies. Most have six legs, sometimes eight, and many possess wings. An insect’s body comprises three

Bird Migration and Adaptation

Many bird species migrate to benefit from seasonal temperature changes across the world, thereby improving their access to food resources and habitats suitable for breeding. These migrations vary among different groups. Numerous birds undertake long-distance migrations, which begin depending on day length, night length, and weather conditions. These birds lay their eggs in temperate or polar regions and spend their non-breeding period in tropical areas. Given that migration requires a significant amount of physical energy, and some birds cross deserts and vast oceans without feeding, birds increase their body fat and reduce the size of some internal organs before migration to ensure sufficient energy reserves during flight. Terrestrial resident birds migrate up to approximately 2,500 kilometres, while coastal resident birds may migrate up to 4,000 kilometres. However, the bar-tailed godwit is the most accomplished long-distance migrant bird, capable of flying up to 10,200 kilometres non-stop. Seabirds also undertake exceptionally long migrations. The longest migration among birds belongs to the sooty shearwater pigeon, which travels approximately 64,000 kilometres from its breeding grounds in New Zealand and Chile to the northern Pacific regions of Japan, Alaska, and California.

Nature has developed special mechanisms to regulate the calorie intake of birds to ensure that fat accumulation does not impair their flying ability. Approximately three million years have been devoted to designing an efficient flying animal, and nature does not permit fat deposits to undermine a bird’s efforts. Despite the emphasis on lightness, birds must inhabit a healthy environment that allows them to expend only the energy necessary for normal bodily functions. Logically, overweight birds cannot fly sufficiently well to survive the hardships of the wild.

Psychological Differences of Songbirds Compared to Other Birds

Over the past decade, scientists have discovered through numerous studies that individual birds, like other animals, possess unique personalities. One definition of personality—at least as used in humans—is a distinct pattern of thoughts, feelings, and behaviours that make an individual unique. It remains to be established whether non-human animals can also possess personalities. Although observing and measuring animal behaviour is generally straightforward, assessing animals’ thoughts and feelings remains challenging. This difficulty contributed to researchers initially rejecting the concept of unique personality traits in animals. The first recorded use of the term ‘personality’ in reference to a non-human animal in a major scientific journal was in 1993, referring to an invertebrate—the octopus.

Janice Dickinson, a biologist at Cornell University, states: “Anyone who observes animals knows they differ.” Dickinson was first struck by individual differences among birds while conducting research on western waterbirds during her postdoctoral studies at the University of California. She recalls: “We were in Carmel Valley trying to catch birds. We had traps with plexiglass panels that fell in front of the entrance after the bird entered the nest box. Sometimes I made mistakes and the bird escaped. Some birds returned directly to the box after resetting the trap, while others, noticing the change, perched with food in their beaks on top of the box but refused to enter.”

Despite this, many questions about animal personality remain, such as whether its origins are genetic or environmental.

Evidence of Nature

A group of European scientists found evidence of a ‘curiosity gene’ in the great tit, a small songbird similar to the North American chickadee. They released newly fledged tits in a large room with wooden perches and measured how long each bird took to land on a perch. In a separate experiment, they introduced an unfamiliar model—a Pink Panther toy—into the bird’s cage and observed whether the bird flew back or jumped up to investigate and how long this took.

They also analysed the genetic characteristics of each bird, focusing on the Drd4 gene, which controls dopamine receptor structure in the brain. Birds possessing this gene variant showed the greatest tendency to explore new objects. Field experiments in natural environments corroborated these findings.

Evidence of Nurture

A research team at the University of Memphis observed mother Florida scrub jays to assess their attentiveness to their chicks. Shortly afterwards, they took blood samples from the chicks to measure the stress hormone corticosterone (CORT), finding the highest levels in nests where mothers paid the least attention.

Approximately seven months after fledging, the birds were trained to retrieve a pile of shelled peanuts, and a series of tests measured each bird’s boldness. Although the researchers tested only ten birds so far, Stephen Schoch, a scientist at the University of Memphis, remarked: “When we analysed the CORT data, we were very surprised. The CORT level predicted how fearful the birds were approximately seven months later.”

Personality Research Beyond an Academic Exercise

In the 1970s, George Archibald Bald, former director of the International Foundation for the Tern, pioneered captive breeding programmes for endangered birds such as a species of tern. When considering good mating pairs, what does a biologist consider? It appears akin to an eHarmony advert. Bald stated: “We looked at their personalities.”

Bald explained: “Sometimes a normal bird mates with a crippled bird. Sometimes an older bird pairs with a much younger one. What an aggressive female needs is a more aggressive male. If the female does not submit to the male, she may not experience the hormonal changes necessary to allow egg-laying.”

Coordinated Duetting in Songbirds

When a white-browed sparrow-weaver begins singing, its mate joins at a precise time. They take turns singing in close synchrony. A team led by researchers at the Max Planck Institute for Ornithology in Seewiesen, Germany, used mobile transmitters to simultaneously record neural and vocal signals from paired birds singing duets in their natural habitat. They found that neural activity in the singing bird’s brain changed and synchronised with its partner’s song. Subsequently, the brains of both animals effectively functioned as one, resulting in perfect synchrony.

Songbirds possess brain regions resembling those in humans that exhibit similar neural dissociation between vocal production, auditory perception, and memory. Evidence for lateralised neural responses exists in these brain areas in both humans and songbirds.

Affection and Social Bonds in Birds

Can the sociability of birds, their ability to fly, and spending part of their lives in the sky be associated with increased affection? Mild courtship behaviours such as mutual preening or food sharing indicate a bond between paired birds that can readily be considered love. Parental birds care for their hatchlings as attentively as might be interpreted as parental love.

Few birds, instead of relying on other animals, form emotional bonds with humans, often reciprocating feelings of love. This is not material attachment but an emotional one.

However, these findings do not explicitly indicate that the social nature and flight ability of birds result in greater affection.

Flightless Birds

Many interpretations of the Qur’anic phrase about birds ([Qur’an 6:38]: “There is no creature on earth or flying with its wings except communities like you…”) suggest it is a clarifying clause; however, this is not the case. The Creator has made advanced creatures that fly without wings.

Mammalian Classification

Mammals are a class of vertebrates characterised by mammary glands—which produce milk to nourish young in females—fur or hair, and endothermy (warm-bloodedness). Although mammals are far less diverse and abundant than other animals, including other vertebrates such as birds and fish, they are the most advanced vertebrates due to the complexity of their organs, especially the nervous system and larger brains.

Mammals possess varied dentition and typically breathe using lungs. Sizes range from a species of bat measuring 30–40 millimetres to the 30-metre blue whale. Lifespans vary from two years for a type of blind mole rat to 211 years for the bowhead whale. The bat is the only mammal capable of true flight; flying squirrels and colugos glide but cannot fly.

Most mammals give birth to live young, although some lay eggs, such as the platypus. Some bear underdeveloped young and carry them in a pouch (marsupials), such as kangaroos. Live birth also occurs in some non-mammalian species and thus is not exclusive to mammals.

Reproductive Anatomy

In male mammals, the penis serves both excretory and copulatory functions. Depending on the species, erection may be supported by blood flow to vascular tissues, spongy tissue, or muscular action. The penis is often retracted within a foreskin when flaccid. Some placental mammals possess a bone within the penis. Marsupials typically have a claw-like penis, whereas the Australian echidna’s penis is four-headed, with only two functional. In most mammals, the testes reside in a scrotum behind the penis, while in marsupials, the testes are located in front. Female mammals generally possess a clitoris, outer and inner labia, paired oviducts, one or two uteri, one or two cervical openings, and a vagina. Marsupials have two lateral vaginas and a central vagina.

Penis length correlates positively with body length and the ratio of penis length. No correlation has been found between BMI and penis size or erection parameters.

Brain and Intelligence

In intelligent mammals, the cerebrum is larger than other brain parts. Although intelligence is difficult to define, indicators include the ability to learn and behavioural flexibility. For example, mice are considered intelligent as they can learn and perform novel tasks, which may be vital when encountering a new habitat. Food gathering in some mammals correlates with intelligence. A herbivorous deer has a smaller brain than a cat, which must plan to deceive prey. Tool use may reflect various levels of learning and cognition. Sea otters use stones systematically to break open shells, spending up to 21% of their time using tools. Another example is raccoons, which can remember the solutions to tasks for up to three years.

A government must possess authority, and while having strong power, it should show kindness and speak to the people with compassion and affection, so that the stench of arrogance is not perceived from it. Although the United States is among the countries with the highest number of executions globally, it presents itself as a symbol of mercy and kindness, and appears under the guise of democracy.

By reason, society requires a leader, and the only outstanding quality that must be manifested in leadership, which is necessary to rescue the community from difficulties, is authority. However, it is essential to examine what authority is, what its components are, and which type of authority is required in each time and circumstance. Is authority a general and ambiguous concept, subject to degrees of strength, intensity, weakness, or fragility?

A meticulous examination of human societies reveals that whenever a country or group has a strong leader, progress is made towards development. Conversely, any nation with a weak leader experiences decline and backwardness. This is the most significant reason for the destruction of many human societies and even social groups of animals. For example, the social organisation of bees demonstrates this. A hive with a queen of noble lineage can gather the bees around herself, protect the hive from calamities, and nurture future generations effectively. But if the queen lacks authority, the hive faces constant attacks from external enemies such as red bees and internal parasites like mites. A powerless queen cannot dare to order the bees carrying poison to be killed. When this courage is absent, the venom spreads throughout the hive, gradually destroying their community. Similar dynamics govern the family of ants.

Zoology

It is necessary to understand the traits of animals— which are fierce and majestic, and which are gentle and beautiful. Indeed, mercy and severity must be seen together; in the heart of every majestic being, beauty exists, and in every beautiful being, majesty is present. Those who manifest both majesty and beauty possess a collective rank. The perfection of every being, from prophets to animals, plants, and even devils, operates within its own realm and according to its creation and nature: “Everything is made easy for what it was created for.” The ferocity of the wolf is its perfection, and a lack of fierceness constitutes deviation from perfection. God created it so that it would be fierce. If animals did not possess attributes of severity, they would become extinct. The measure of perfection of a species of animal and its superiority over others is its proximity to human perfection, which is the standard and measure. One species may be closer to humans by intelligence, another by beauty, another by dignity, another by sensitivity, and another by cleanliness. Proximity to humans is the criterion and standard for assessing the perfections of a natural phenomenon. The degree of perfection in a human being is also measured by his closeness to the perfect human.

Animals have defensive powers: some rely on their intelligence, some on hearing, some on sight, some on horns, some on their tails, and some like snakes on their venomous bite. The lion—king of the jungle—cannot defeat an ant. A killer of lions can be an ant, as it can crawl under the lion’s nails and tickle it. The lion can dominate a tiger, leopard, or wolf, but it is powerless against an ant that tickles it beneath the nails. The lion cannot do anything against such ants except to flee. An elephant, despite its great size and strength, can be brought down by a mosquito. If a mosquito enters an elephant’s nostrils, it disrupts the animal. Ants and mosquitoes are no less significant than lions and elephants. God has endowed each creature with authority—some through their size, others through their smallness. This is the divine system of creation. A fly is a miniature peacock; if its wings are examined under a magnifying glass or telescope, they appear like a thousand-coloured emerald or a miniaturised atlas, concealed so that its beauty is not worshipped. The fly is more beautiful than a cow.

Animals in the wild avoid mistakes to the maximum degree. An error in natural life is a matter of life and death; one mistake can cause death. Both the lion and the gazelle are adept runners, but the gazelle can run for a longer duration and tire later, while the lion tires sooner. The survival of the gazelle depends on its long-distance running; if the lion cannot catch it in the short term, it fails to hunt. Each loses due to a mistake. Mistakes mark the point of decline in wild animals. Therefore, animals must use their awareness and intelligence for survival.

Zoology is a neglected science in some fields, despite the fact that Imam Sadiq (peace be upon him) incorporated zoological knowledge into his theology. For example, he said that everything the elephant has, the mosquito has as well; in other words, God has exaggerated the size of the mosquito in the elephant’s blueprint, or minimized the elephant in the mosquito’s blueprint. When God intends to fight Abraha, He does not deploy an army of elephants and lions but instead sends forth a small swarm of birds.

Why did some roosters in the past know when morning had arrived? Nowadays, some roosters, having been fed impure food, begin to crow partway through the night, and their biological clocks no longer indicate morning. Dogs also used to bark timely, except when they sensed a distant incident within dozens of kilometres, for which they would bark. The dog’s senses are so sharp that it can detect distant events, whereas a human may not even notice if their pocket is pickpocketed. One must not oppress or harm animals. The awareness of animals is such that one can pray, “O God, grant me knowledge, intellect, and love to the extent of a rooster, a dog, a cat, or a chicken.” One must observe and assess the life of each species. Animals live according to their nature, devoid of hypocrisy, duplicity, and corruption.

Each animal species has a distinct perfection; a trait admired in one species, such as the cat, may be blameworthy in another like the dog, and vice versa. God is with the weak and those with broken hearts. One should never engage in conflict with the weak nor punish or harm them. Justice should begin with the strong, not the weak, as doing otherwise is cowardice. Among animals, the scorpion is weak, miserable, and aggressive; it stings everyone, even the saints, whereas the lion does not hunt unless hungry, hunts only what it needs, and is not unnecessarily ferocious. At least a human should be like a snake, which harms no one unless provoked. A person with such tyrannical cruelty that the curse of God upon oppressors is invoked upon them—what benefit is their religion, prayer, or clerical garb?

Snakes are among the most adaptable creatures to their environment. They even synchronize their diet with environmental phenomena and successfully hunt and survive. If snakes inhabit an area abundant with frogs, they rapidly develop new traits to become frog-eaters. Snakes’ evolutionary clock is rapid and advanced, allowing them to quickly alter body shape and dietary habits due to high adaptability and advanced chemical detection systems.

Detailed Zoological Knowledge

Science deals with descriptions of objects rather than the essence or truth of things. Knowledge comprises complete propositions, unlike science, which only concerns itself with descriptions. Humans lack knowledge of their hunger, possessing only sensory awareness; similarly, animals are aware of their hunger. The difference between humans and animals is that humans have knowledge of their knowledge, whereas animals do not. Thus, animals comprehend actualised and partial phenomena, not general matters. For example, animals do not perceive danger unless it confronts them. Knowledge and science must not be conflated; their boundaries must be maintained in scholarly discussion.

Animal Training

Animals undergo only brief training because their instincts, sensory perceptions, and souls are limited and do not roam freely.

Animal Remembrance

Animals can become negligent and inattentive due to their awareness level. Such a characteristic allows for remembrance and recollection, so animals too possess memory. Negligence results in natural consequences, such as a predator hunting them, although such instances are rare. The slaughter of animals conducted naturally or by automatic devices is unrelated to their remembrance or memory.

Animal Hygiene

Many animals groom themselves, cleaning with water. Some lick themselves to maintain cleanliness.

Animal Health

Life exists in humans, animals, and plants; the life of plants and animals is generally natural and healthy. Plants may suffer wilting, drying, and drought, but most remain lush and healthy. Most animals also live healthily. Attacks by wild animals on others are necessary for their survival and healthy development. However, humans with reason and free will currently live in poorer health than plants and animals.

Interchange of Animal Traits

In evolution and extinction, there is a relationship between cohabiting phenomena. For example, snakes and mammals inherit traits from one another through symbiosis; venomous reptiles have evolved over history by inheriting each other’s traits, engaging in exchanges of characteristics.

Geology and Evolution

In geology, it is said that millions of years ago a sea existed where mountains now stand, or vice versa. Phenomena have orderly arrangement and harmonious rotation, leading to perfect movement. In the past, humans lived up to a thousand years, but today the average lifespan does not even reach a hundred years. Changes in animals, humans, and terrestrial phenomena over time are voluntary, and mutual association affects the perfection of cohabiting phenomena. Coexistence causes the transfer of traits between phenomena. This is because phenomena lack essence to undergo essence revolution or trait exchange. What exists in the realms are determinations, manifestations, and appearances; everything can transform accordingly. Governments may one day support the poor and oppressed, and at another time favour the wealthy. A currently weak and oppressed nation like Afghanistan might one day engage in a war involving billions of lives. Times and conditions change, and the phenomenon adapts to new requirements.

Conclusion

Power and authority are essential in leadership and governance, but must be tempered with mercy and justice. The balance of severity and kindness, the understanding of nature, and the perfection of beings in their own realms provide guidance for human society and governance. An understanding of zoology enriches human knowledge and provides insights into natural order, survival, and coexistence.

According to the “Mental Time Travel Hypothesis,” animals, unlike humans, are unable to mentally travel backward in time to recall specific past events (episodic memory) or forward to anticipate future needs (future planning). Until recently, there was limited evidence supporting either ability in animals. However, experiments on food-storing birds challenge this hypothesis by demonstrating that the western scrub-jay forms unique, integrated, flexible, and testable memories of what, where, and when they have hidden food. Moreover, these birds can adjust their caching behaviour in anticipation of future requirements. Therefore, it can be argued that some animals possess elements of episodic memory and future planning.

Nevertheless, the evidence for shared characteristics between animals and humans is largely restricted to physiological traits, with psychological features either not targeted or not sufficiently investigated in a conclusive manner.

Olfaction

The African bush elephant possesses the most powerful sense of smell within the animal kingdom. This species has approximately 2,000 highly sensitive receptors in its trunk, a remarkable figure compared to around 1,000 receptors in dogs and 400 olfactory receptors in humans. Biological studies indicate that over generations, African bush elephants have inherited twice as many olfactory receptor genes from their ancestors. Interestingly, elephants top the list of olfactory gene counts with 1,948 genes, while cows and dogs rank second and third with 1,186 and 811 genes respectively.

Most animals can detect the presence of fire; however, the jewel beetle can smell a burnt pine tree from a distance of 16 kilometres, a capability vastly superior to the few metres detectable by an average human. There are three clear evolutionary reasons why jewel beetles have developed this trait: primarily to gather food, secondly to ensure mating success, and thirdly to safeguard their eggs, which they deposit inside pine trees.

Bears may have brains only a third the size of humans’, yet the region responsible for their sense of smell is five times larger. A bear’s olfactory sense is more than 2,000 times more acute than a human’s, enabling it to avoid danger, locate food, find mates, and monitor the whereabouts of its offspring. Bears can detect the scent of a carcass from 30 kilometres away and polar bears can track the scent of a potential mate over distances exceeding 160 kilometres.

Fish release specific scents for mating purposes; for example, the goldfish emits this scent through its urine. Fish use this chemical signalling not only to identify mates ready for reproduction but also to assess the readiness of their own glands. Sexual pheromones are predominantly produced by male fish. Even smaller fish species with weaker olfactory capabilities possess sexual scent detection. Using smell, fish can recognise population groups, distinguish species, and identify relatives. Species such as salmon return to the exact locations where they were born to spawn, relying on their sense of smell to complete their life cycles. Salmon typically swim thousands of kilometres away from their birthplace, spend adulthood in the sea, and then return to their natal rivers for spawning—often finding the precise spots where their eggs were initially laid. Many fish possess highly developed olfactory organs; for instance, sharks can detect the scent of blood from several hundred metres underwater.

Psychological Effects of Reduced Olfactory Sense in Humans

What psychological impacts arise from humans’ comparatively weaker sense of smell? Are these effects more pronounced in individuals with naturally or acquired olfactory loss? It is well documented that loss of smell and taste negatively affects emotional health and quality of life, leading to feelings of loneliness, fear, depression, as well as difficulties in social and sexual relationships. Research conducted on COVID-19 patients has shown that these psychological issues may persist to some extent even after recovery.

Olfaction is widely prevalent across the animal kingdom. Human and animal studies indicate that odour perception is regulated by experience or physiological states (such as hunger), and certain odours can evoke emotions and trigger the recall of emotional memories. Additionally, odours influence psychological and physiological states. Evidence suggests that some odours can modulate emotions and cognition, with potential applications for treating psychological disorders—for example, in alleviating stress.

Touch

Touch is perhaps the most complex sense to define due to its multifaceted nature. Mantis shrimps and sea cows exhibit “remote touch,” meaning they can sense objects without direct contact, even if the objects are at a distance. The body of the sea cow is covered with thousands of whisker-like hairs that enable it to detect objects, temperature changes, water currents, tidal forces, and environmental features.

Spiders are among the few animals highly sensitive to touch. Their legs are covered with numerous hairs capable of detecting and tracing vibrations produced by other animals or objects, facilitating prey capture as movements transmit through their webs. Interestingly, spiders construct their webs in illuminated areas to trap prey rather than in dark places.

The gecko is a lizard species with unique characteristics, including the ability to shed its skin when threatened. Even a slight touch can provoke a reaction. Their bodies are dense, sometimes resembling bone-like structures, and their skin is highly resilient, making it resistant to injury.

There remains a lack of research into the psychological characteristics endowed by a highly developed sense of touch in certain animals. For example, do blind individuals, who tend to have a heightened sense of touch, exhibit similar psychological traits?

In animals such as sea cows and spiders, the presence of dense hair enhances tactile sensitivity. Does this imply that more hair correlates with a stronger sense of touch? Additionally, why are there numerous hairs in the human genital region? Is the emergence of sexual pleasure after puberty and the growth of genital hair connected?

At the base of each hair follicle are sensory nerve fibres that wrap around the hair bulb. When a hair bends, it stimulates the nerve endings, allowing the individual to perceive hair movement. One primary function of hair is to serve as a sensitive tactile receptor.

Neuroscientists have uncovered the mechanisms linking the sense of touch in the skin to the nervous system. Recent findings open new avenues for understanding how information gathered from hairy skin is processed by the brain. Researchers have marked two other types of tactile nerve cells and discovered that each hair type possesses a unique set of nerve endings. Furthermore, their novel marking tools revealed that each hair type is evenly distributed and patterned across the skin. Ginty, a neuroscience professor at Johns Hopkins University, states, “This means each hair acts as a unique mechanical sensory organ.”

Thus, four main functions of hair have been identified: hair enhances the sense of touch, regulates body temperature, protects the body from harmful objects, and assists in individual identification.

Pubic hair serves a function similar to eyelashes or nasal hair, trapping dirt, dust, and potentially harmful microorganisms. Moreover, hair follicles secrete sebum, an oily substance that inhibits bacterial proliferation.

The primary role of pubic hair is to reduce friction during sexual intercourse and prevent the transmission of bacteria and other pathogens. Some studies indicate that frequent removal of pubic hair is associated with an increased risk of infections such as HPV and herpes.

Vision

Birds of prey—especially eagles—possess extraordinarily sharp vision. Eagles (and certain falcon species) see with eight times the acuity of humans. The retina of an eagle’s eye contains approximately one million sensory cells per square millimetre, enabling it to identify prey nearly a mile away and track it even while flying overhead. This makes them formidable hunters.

Mantis shrimps have one of the most complex visual systems in the animal kingdom, with 16 types of photoreceptors capable of detecting visible and ultraviolet light. They are the only known animals to perceive circularly polarised light. Additionally, they can gauge light depth with one eye while moving the other independently.

Octopuses, with their flexible bodies and eight powerful tentacles, are unique animals partly due to their exceptional vision. For instance, they possess so-called “polarised vision,” allowing them to regulate the amount of light entering their eyes. This enhances their ability to see clearly in dim underwater environments and to hunt prey at greater depths.

Dogs perceive the world as less colourful than humans do because their retinas contain only two types of colour receptors (yellow and blue), whereas humans have three (yellow, blue, and red).

An ostrich’s eye is larger than its brain.

An owl’s vision is 82 times sharper than a human’s.

The Indian night monkey, a mammal inhabiting Southeast Asia, is only about ten centimetres long (excluding its tail), yet its eyes are 3.1 centimetres wide, encompassing most of its head. This gives it the highest eye-to-body ratio among animals. Its large eyes enable it to see as clearly at night as humans do in daylight.

Elephants have relatively poor eyesight, which they compensate for with heightened senses of smell and hearing.

Mole rats have eyes the size of a pinhead and can only distinguish light from darkness, relying on their olfactory and tactile senses for navigation.

Does superior visual acuity correlate negatively with social interaction and dependence on others? Are highly sighted individuals less social than those with average vision?

The closest related research suggests that sensory perception is often studied focusing on a single sense (such as touch, smell, or vision) and considered subjective and mental. However, some robust articles argue that perception requires action. This concept is supported by Brian Doe’s paper titled “Distributed Perception: Collaboration among Recognisable, Actionable, and Responsive Semiotic Agents.” Doe analysed recorded interactive video situations involving blind individuals and demonstrated that perception emerges not only through sensory action but also via participants’ interaction with other agents such as digital systems and dogs. His study reveals aspects of action organisation generated by semiotic acts that share information about their perception of the surrounding world, making situations manageable for participants.

Regarding olfactory dysfunction—particularly prevalent during the COVID-19 pandemic due to various viral strains—its consequences range from difficulty identifying dangerous pathogens to impairments in social functioning and social behaviours. Ellen Bloomquist and Marlies Hoffer, professors of psychology in Sweden and Canada, have reported communication disorders, reduced social support, loss of communal eating experiences, health anxieties, and changes in sexual behaviour.

Is humans’ weaker sensory perception compared to animals a result of higher intelligence that compensates for sensory deficiencies?

Senses assist all animals in orienting themselves within their environments, finding food, avoiding danger, or locating conspecifics. Animals may possess senses humans lack. For example, many birds can see ultraviolet light, which humans cannot without specialised equipment. None of these examples imply superior intelligence in humans.

Taste

Butterflies have taste receptors on their feet.

Catfish possess between 100,000 and 175,000 taste buds—over ten times more than humans. These taste buds are not confined to the mouth but are distributed across the body, primarily on the facial barbels. Catfish use these taste buds not only to sample their prey but also to locate prey based on the taste of water. This ability aids their survival, given that they inhabit dark and muddy environments with limited vision.

Sensory Perception

The cavefish exemplifies the principle that when one sense is diminished, other senses become more acute. Living in a relatively dark environment, the cavefish’s vision is virtually non-functional. However, its hearing is highly sensitive, allowing it to detect even the faintest sounds at around one kilohertz or lower. This ability helps the cavefish efficiently locate prey and filter out irrelevant environmental noise.

Humans can perceive sounds within a frequency range of approximately 20 Hertz to 20 kilohertz. It is noteworthy that infants can hear slightly higher frequencies beyond 20 kilohertz, but this sensitivity diminishes with age, with typical adults hearing up to about 15–17 kilohertz. The wax moth (Galleria mellonella) possesses the most acute hearing of all animals, capable of detecting frequencies as high as 300 kilohertz—roughly 15 times higher than the upper limit of human hearing. This extraordinary ability enables the moth to evade bats, its natural predators, which use ultrasonic echolocation sounds inaudible to most species. The wax moth hears these signals as an early warning system, facilitating its escape.

Snakes are generally deaf and perceive their surroundings via vibrations transmitted through the ground and water. Species such as vipers, pythons, and boas possess specialized facial structures called “pit organs,” containing membranes capable of detecting infrared radiation emitted by warm-blooded prey at distances of up to one metre.

Some animals can voluntarily close their ears, such as the hippopotamus, sea otter, and water horse.

Reproduction

Almost all animals reproduce sexually, though some species, like hydra and other cnidarians, are capable of asexual reproduction through budding and fragmentation. In certain circumstances, species such as aphids reproduce asexually via parthenogenesis—a process by which a complete organism develops from an unfertilized egg. This phenomenon is observed in numerous invertebrates and vertebrates, including annelids, molluscs, crustaceans, insects (notably honeybees and stingless bees), fish, amphibians, and reptiles such as some snakes. Most animals exhibit polygamous mating systems; only about 5% are monogamous, such as the Eurasian beaver, which forms lifelong pair bonds.

Reproductive behaviours vary widely among species, and this section highlights mating behaviours in some animals.

Psychological Considerations of Asexual Reproduction

What psychological differences exist between animals capable of parthenogenesis and those that reproduce sexually? Can it be inferred that species lacking sexual reproduction are evolutionarily or cognitively simpler? Are homosexual humans intellectually inferior to heterosexuals?

One disadvantage of parthenogenesis is the lack of genetic diversity; without gene flow between populations, adaptability to changing environments is reduced. Environments are often unstable, so genetically diverse populations typically fare better in survival. Asexual reproduction thus limits biodiversity and can complicate population control, as diseases may affect entire genetically uniform populations. Importantly, these findings do not address intelligence.

Mating Systems and Psychological Effects

Most animals are polygamous, with only a minority exhibiting lifelong monogamy, such as the Eurasian beaver. Does this mating system influence behavioural traits such as jealousy, loneliness, or competitiveness? Conversely, polygamy can facilitate shared responsibilities in child-rearing and household tasks.

In many species, females initiate sexual activity when receptive, only engaging with males when they choose. Does this natural behaviour contrast psychologically with human societies, where women often consent to sexual activity according to male desire? From a biological standpoint, what constitutes a healthy sexual relationship? Are women who engage in sexual activity only upon their own desire psychologically healthier?

Sexual Activity and Wellbeing

Sexual activity encompasses more than reproduction; it also fosters intimacy and pleasure. Practices such as penile-vaginal intercourse (PVI) or masturbation provide physical and psychological benefits, including stress reduction, enhanced happiness, increased satisfaction with mental health, and improved trust and affection within relationships.

In older adults, sexual activity correlates with better cognitive function. Research shows that sexually active individuals aged 50 to 90 exhibit superior memory and report fewer feelings of depression and loneliness.

These studies focus on physiological and psychological effects but do not address psychological differences related to sexual activity motivated by male or female desire.

Why Sexual Reproduction Usually Involves Two Sexes

Why do most animals require both male and female individuals for reproduction? Could individuals reproduce independently, like clownfish, which can change sex, or land snails, which are hermaphroditic? Is the need for companionship and bonding unique to humans, or do most species require mates?

Most evolutionary studies address these questions from a natural selection perspective, differentiating between natural and sexual selection. As psychologist Geoffrey Miller stated: “Natural selection means living long enough to reproduce; sexual selection means convincing others to mate.” This distinction remains important even when disregarding male-male competition. Sexual reproduction predominates over asexual reproduction in both plants and animals, yet these studies do not explore the need for companionship.

The Reproductive Peculiarities of Neotrogla curvata

The cave-dwelling insect Neotrogla curvata, measuring 3 millimetres, exhibits a rare reversal of genital function: the female possesses a penis-like structure called the gynosome, which penetrates the male’s genital chamber during copulation. Males ejaculate sperm into this internal cavity, which the female draws into her body. Copulation lasts an extraordinary 40 to 70 hours, necessitating firm anchoring by the female’s gynosome, which is covered with tiny spines acting as an anchor, preventing separation without severe injury to the male.

This reversed sexual role contrasts with the usual male competition for females, as in Neotrogla, females compete for males to receive sperm and nutrients contained within the male’s internal cavity. This reversal may be an adaptation to their harsh, food-scarce cave environment, where the female’s ability to secure resources through mating enhances survival.

Psychological Implications of Sexual Role Reversals

In most animals, males are larger and more aggressive due to higher testosterone levels. Exceptions such as spotted hyenas and chinchillas display larger, dominant females. Typically, males compete for access to females, who are the limiting reproductive resource, selecting mates to ensure offspring fitness. The female’s investment in costly egg production makes them the choosy sex, whereas males produce abundant sperm to maximise reproductive success. These dynamics are well-studied but reveal little about psychological differences.

Sexual Desire and Social Behaviour

Clownfish demonstrate sex change ability, transitioning from male to female or vice versa upon reaching sexual maturity. Bonobos exhibit a high degree of sexual behaviour, using sex not only for reproduction but also as a social tool to resolve conflict, reduce tension, and strengthen bonds. Sexual interactions among bonobos are diverse, occurring between males and females, females with females, males with males, and even mothers with sons.

Similarly, dolphins engage in sexual activity purely for pleasure, including both heterosexual and homosexual interactions, and masturbation using various objects, showing complex sexual behaviours beyond reproductive needs.

Is it possible to say that animals which engage in sexual activity for pleasure are intellectually superior to other animals? Psychologically speaking, do individuals who have better and more pleasurable sexual relationships possess higher intelligence? Does having a good sexual relationship contribute to improved mental performance and creativity? Does the fact that dolphins and bonobos are peaceful animals indicate a psychological effect of pleasurable sexual activity in promoting calmness and avoidance of conflict?

Researchers in Maryland and South Korea have recently found that sexual activity in mice and desert mice improves cognitive performance and increases neurogenesis (the production and development of new neurons) in the hippocampus—the area where long-term memories are formed.

A team from the University of Maryland reported that middle-aged mice allowed to engage in sexual activity showed signs of improved cognitive function and hippocampal performance. A group from Konkuk University in Seoul concluded that sexual activity counteracts the detrimental memory effects caused by chronic stress in mice. They wrote: “Sexual interaction may be beneficial in buffering adult hippocampal neurogenesis and maintaining memory function against the suppressive effects of chronic stress.”

If having sexual relations can make individuals smarter, the converse is not necessarily true; in other words, being more intelligent does not imply having more sexual activity.

In fact, a 2007 study published in Neuropsychologia measured salivary testosterone levels in prepubescent boys, including mental prodigies with IQs above 130, average intelligence individuals, and some with intellectual disabilities (IQ below 70). They found that “boys with average intelligence had significantly higher testosterone levels compared to boys with intellectual disabilities and prodigies, with no significant difference between the latter two groups.”

Nevertheless, the dream of becoming smarter through sexual activity may be nothing more than an appealing fantasy. Tracy J. Shors, a psychologist at the Collaborative Neuroscience Centre at Rutgers University, has reported that while many activities can increase the rate of new brain cell production, only successful and diligent learning promotes their survival. As she stated at a 2012 session on “Cognitive Enhancers” at the Society for Neuroscience: “You can generate new brain cells through exercise, the antidepressant Prozac, and sexual activity. If you engage in mental training, you can preserve more of these new cells. If you do both, you can both produce and maintain more cells.”

Dolphins are among the few non-human animals that engage in sexual activity purely for pleasure and can be quite promiscuous, not limiting themselves to intra-group interactions and sometimes even masturbating. Does this make them psychologically similar to humans?

For those who have observed monkeys and apes—the closest evolutionary relatives of humans—in nature, zoos, or on television, it is evident that, in many ways, their personalities reflect human personalities. Scientists such as Dr Blake Morton, a psychology lecturer at the University of Hull, UK, suggest that these similarities arise from a shared evolutionary history with humans and other primates. Many other primates have also evolved to be relatively intelligent and form societies composed of friendships, families, and cultural traditions. To further test this idea, Dr Morton and a team studied the personality traits of bottlenose dolphins (Tursiops truncatus). They gathered data on 134 dolphins, including 56 males and 78 females, from centres in eight countries including Mexico, France, the United States, Curaçao, the Netherlands, Sweden, the Bahamas, and the Cayman Islands.

Dr Morton said: “Dolphins were excellent subjects for this type of study because, like primates, they are intelligent and social. We argued that if factors such as intelligence and sociability shape personality, dolphins should exhibit personality traits similar to primates.”

Human behaviour is described by five personality traits, conveniently abbreviated as OCEAN (Openness, Conscientiousness, Extraversion, Agreeableness, Neuroticism). These include openness (e.g., curious, playful, active), conscientiousness (e.g., reliable, predictable, self-controlled), extraversion (e.g., friendly, outgoing, sociable), agreeableness (e.g., kind, affectionate, helpful), and neuroticism (e.g., anxious, disorganised, emotionally unstable).

Research shows that monkeys and apes possess personality traits identical or similar to humans, but Dr Morton’s team were the first to investigate these traits in dolphins. They found that dolphins, like primates, display personality characteristics associated with curiosity and sociability, particularly openness and a trait combining extraversion and agreeableness.

Dr Morton explains: “Dolphins, like many primates, have brains significantly larger than what their bodies need for basic functions. This brain surplus fundamentally enhances their capacity for intelligence, and intelligent species are often highly curious.”

Throughout our lives, we interact and form relationships with different individuals. Dolphins do the same among themselves. Overall, intelligence and sociability—regardless of the ecosystem one inhabits—may play crucial roles in the evolution of certain personality traits.

Their study, titled Personality Structure in Bottlenose Dolphins (Tursiops truncatus), began in 2012 and was published in the Journal of Comparative Psychology in 2021. The team included Dr Morton, Dr Lauren Robinson from the University of Veterinary Medicine Vienna and the University of Georgia, Ms Sabrina Brando from AnimalConcepts, and Dr Alexander Weiss from the University of Edinburgh.

Seven Remarkable Uses of Animal Faeces

Animal faeces—often used as fertiliser to enrich soil—have various other unusual applications, including:

1. Paper Production: Faeces contain significant amounts of fibre. In Thailand, elephant dung is utilised to produce paper, while in China, panda faeces are used similarly.
2. Medicine: During World War II, German soldiers occupying North Africa suffered severe diarrhoea, whereas local inhabitants displayed resistance. The Germans discovered that locals consumed fresh camel dung upon the first signs of diarrhoea. This practice was linked to the bacterium Bacillus subtilis, which aids digestion and inhibits harmful bacteria. Later, medical professionals isolated this bacterium to develop more conventional treatments. It is noted that camels, despite their medicinal excreta, can become aggressive if unwell, contrasting with sheep, which are generally peaceful and healthy. The meat of rams, regarded for their peaceful nature, is recommended for consumption.
3. Camouflage: At one point, German soldiers believed that camouflaging their weaponry with animal faeces would bring good luck. Allied forces exploited this superstition by designing mines resembling faeces. The Germans, once aware, avoided such piles, prompting the Allies to create mines mimicking faeces already traversed by tanks.
4. Coffee: The world’s most expensive coffee, Kopi Luwak, is made from coffee beans found in the faeces of the civet cat. This animal selectively consumes ripe coffee cherries; its digestive system breaks down the fruit pulp, leaving the beans intact but chemically altered. These beans are collected from the faeces, cleaned, and roasted. This coffee is highly prized and scarce, produced mainly in Indonesia.
5. Gunpowder Production: In South America, particularly on certain Peruvian islands, accumulations of bird guano have formed deposits up to 45 metres thick over thousands of years. These deposits are rich in potassium nitrate, essential for gunpowder manufacturing, and phosphorus, which is also valuable as fertiliser.
6. Water Purification: Mining activities in Bolivia have caused acidification and pollution of water bodies, threatening aquatic life. Certain bacteria, obtained from llama faeces and also from cow and horse manure in the UK, can convert dissolved metals into insoluble sulfide compounds that precipitate and can be removed, thus cleansing the water.
7. Energy Production: Since discovering fire, humans have used animal dung as fuel. Modern applications include biogas production—a mixture primarily of methane, carbon dioxide, and hydrogen sulfide—resulting from anaerobic digestion of biomass by methanogenic bacteria. Methane, constituting 60-70% of biogas, is a clean and efficient fuel, generating considerable thermal energy without producing toxic carbon monoxide. Biogas serves as a renewable energy source, replacing fossil fuels safely for domestic use.

Therapeutic Uses of Animal and Bird Faeces

• Duck, hawk, and other hunting bird faeces are rarely used due to their strong heating properties.
• Goat dung, especially from mountain goats, is effective in stopping bleeding. When burnt, its heat diminishes, becoming milder and useful against diseases like rabies and joint stiffness.
• Pigeon droppings cleanse the complexion and relieve joint pain; mixed with honey and flax seeds, they treat boils and burns.
• Pigeon and sparrow faeces are beneficial for whitening eyes; swallow faeces is the most effective.
• Gecko faeces help remove black spots on the face.
• Sheep dung combined with vinegar treats skin growths such as warts and corns.
• Fresh cow dung applied to wounds reduces inflammation, stops bleeding, and alleviates joint pain.
• Cooked cow dung mixed with olive oil aids in removing embedded foreign objects from the body.
• Chicken faeces serve as a remedy for colic and act as an antidote to poisonous mushrooms.
• Consumption of carrion-eating chicken faeces induces miscarriage.
• Burning male cow dung repels mosquitoes.

Largest Faeces in the Animal Kingdom

The largest faeces belongs to the blue whale, the largest animal on Earth. A single defecation can release up to 200 litres of faeces, which smells somewhat like dog faeces but has a bread-crumb-like consistency.

Animals Without Faeces

Some organisms, such as Tardigrades, defecate only during moulting, and this cannot be classified as true faeces. Certain mites (e.g., Demodex) lack an anus and store all waste internally until death. Sea squirts also lack an anus; although they excrete waste, their process differs from typical animal defecation.

Cloaca

The cloaca is a common cavity in many vertebrates where the intestinal, urinary, and reproductive tracts converge. It is found in amphibians, reptiles, birds, cartilaginous fishes (e.g., sharks), and monotremes (egg-laying mammals like the platypus), but not in placental mammals or most bony fishes. Some animals possess a phallic organ within the cloaca to facilitate sperm transfer. Most birds mate via cloacal contact, known as the “cloacal kiss.” Humans have a cloaca only during embryonic development, which later divides into separate openings. Some congenital disorders result in persistent cloaca.

Surplus Killing and Its Implications for Predators

Surplus killing leads to a reduction in the food reserves available to the predator, thereby adversely affecting its food security. It also results in wasted energy expenditure by the predator and increases the risk of injury during hunting. Nevertheless, there are benefits for the predator that justify the persistence of this behaviour. For instance, surplus killing enables the predator to provide more food for its offspring or conspecifics, enhances its hunting experience, and creates opportunities for future scavenging of the remaining prey carcasses. For example, weasels typically engage in surplus killing in late autumn to store carcasses for the cold winter days. Similarly, wolves exhibit this behaviour, especially during heavy snow winters. On 7 February 1991, in Denali National Park, six wolves were observed to have hunted at least 17 caribou, leaving many carcasses untouched. However, by 12 February, approximately 30 to 95 per cent of each carcass had been consumed, and by 16 April, the wolves were observed feeding again on these carcasses.

Surplus killing generally occurs when predators encounter a large number of trapped prey; however, it is rarely observed in open plains, where prey have ample opportunity to escape and predators struggle to achieve even a single successful kill.

What common psychological traits do animals that engage in surplus killing, such as wolves, share? Is there a specific physical characteristic that endows them with this ability?

Research indicates that although wolves possess unique personality traits, they are highly social animals, and group members learn from one another. Therefore, each case varies.

Many traits observed in dogs are also found in wolves, and vice versa. Both are social animals. Like elephants, gorillas, and whales, they teach their young, care for injured members, and live in family groups. Wolves are complex, intelligent, playful, and family-oriented animals, exhibiting strong cooperation within hunting packs. A clear distinction between dogs and wolves is that dogs are scavengers, while wolves enjoy hunting live prey and do not resort to scavenging unless they are unable to find live food. Dogs tend to be timid scavengers, fearful of approaching live animals. Dogs focus on scavenging continuously, driven not by satiation or pleasure but rather by interfering with other dogs’ use of resources, whereas wolves hunt for satiation and enjoyment.

Wolves communicate, cooperate, and share knowledge across generations. Older wolves, as more experienced hunters, share strategies and hunting techniques with younger members, transmitting knowledge from one generation to the next, thereby maintaining their unique cultural group.

Sadism in Predatory Behaviour

Some animals, such as felids, appear to ‘play’ with their prey, which some interpret as evidence of a cruel nature; however, this behaviour has its own reasons. Cats do not consume mice immediately but play with them repeatedly. This sadistic behaviour is intended to prolong the prey’s suffering. Lions, leopards, and tigers also exhibit similar behaviours to some extent. A cat requires great concentration and patience to capture a fish, lying in ambush with composure until striking it with a single blow.

Deception

The cuttlefish, often mistaken for squid, is a marine mollusc. Studies show that male cuttlefish sometimes disguise the half of their bodies facing a female with the male’s attractive colour patterns, while displaying female patterns on the other half, thereby misleading rival males into thinking there are two females present and deterring interference.

The spiny mouse has the unique ability to shed its skin when threatened by predators and escape. It is the only known mammal capable of regenerating lost body parts, including hair follicles.

Certain shrimp species, such as the pistol shrimp (5.2 cm in length), produce an extremely loud snap that stuns and incapacitates their prey. Despite their small size, pistol shrimp generate one of the loudest sounds among marine animals. When snapping their claws together, they create a cavitation bubble that produces a shockwave and a noise akin to a sonic boom, disorienting the prey for easy capture.

What psychological traits do animals with deception or special defensive mechanisms possess? Can it be posited that individuals with such psychological traits must inherently possess specific physical or mental abilities?

Intelligence

Intelligence is a prominent human attribute and manifests in various forms, such as verbal-linguistic intelligence (communication skills), spatial intelligence (mental visualization), logical-mathematical intelligence (problem-solving abilities), and emotional intelligence (recognition and management of emotions). Other forms of intelligence also exist and can be delineated through the study of cognitive functions. When discussing animal intelligence, however, very different terminologies and frameworks are applied.

The study of animal intelligence has a long history. Since Darwin’s publication of On the Origin of Species, scientists have sought to understand animal cognition and compare it to human thinking. Broadly, animal intelligence can be defined as a set of skills and abilities enabling animals to survive and adapt in their specific environments.

This means animals can learn, change habits, and adapt behaviours in response to their surroundings. Many species also form social groups. All these traits depend on the animal’s information-processing capacity, which allows for comparative judgements of intelligence among different species.

However, scientific objectivity and simplicity are often goals pursued in science to discover universal truths. Nonetheless, the study of animal cognition occupies a unique philosophical domain in adaptive cognition: the human-animal gap and questions regarding the extent and continuity of human and animal minds. This inquiry is normatively non-neutral, as scientific perspectives on this gap can justify or undermine human-animal relationships.

Animal Perception

Animals possess sensory perception, imagination, and illusion. They lack intellectual concepts, discovery, and insight; however, each has the capacity for perception within a broad sensory range, often beyond ordinary senses, particularly if endowed with a refined spirit. Such extensive perception enables them to evade danger and harm.

Some animals demonstrate a degree of human rationality; these are creatures possessing the rank of humanity and its effects, albeit without a human physical form. Some individuals may blend or intertwine in both content and appearance across these ranks, breaking the boundaries between levels.

It may occur that a plant reaches the threshold of animals, or an animal the threshold of humanity, or a human the threshold of angels.

Bestial humans, had they been created in human form, would have resorted to denial and disbelief. However, by divine grace, they were not fashioned in human guise, for they could not fulfil the rights and duties incumbent upon humans. Conversely, human-like animals are the unbelievers who ought to have been created as beasts but, through indulgence and cunning, were accepted at the human rank and given a human form. In the material world (nasut), creatures trapped at such thresholds and constraints face peril. If human, their dominant bestial traits become evident; if animal, some human qualities are visible. Consequently, one cannot rigidly classify intelligent phenomena into animals, humans, jinn, and angels, as many creatures are conditional and borderline. Existential phenomena coexist according to a particular order, influencing one another; each is coloured by its companions. Association with animal-level phenomena causes humans to descend from their lofty rank, weakening thought and rendering the comprehension of complex matters difficult. Those who associate with animals gradually experience a decline in intellectual and cognitive levels. Even professionals dedicated to physical training and sport exhibit similar trends, as excessive focus on the physical body diminishes thought and leads to cognitive shortcomings in life. This is true for those involved in animal husbandry and bodybuilding. Continuous interaction with animals tends to reduce one’s intellect to that of an animal, implying a kinship at least to some degree.

It is notable that some divine prophets briefly engaged in shepherding and herding but never adopted it as a profession. God appointed them to this task so that they would experience gentleness and forbearance with people, avoiding undue harshness that might alienate others.

The Contrast between Wild and Domestic Animals

Animals present a contrast between wildness and domestication; no wild animal exists without a corresponding domestic counterpart.

Chapter Three: Specific Characteristics of Certain Creatures

Ants

Ants and snakes possess highly developed tracking abilities. Both are gentle and sweet-natured. They act purposefully and adhere to collective rules. Both are harmless and harmonious by nature. A snake is harmless and non-venomous unless it is moving; in motion, it becomes deadly. Similarly, venomous and toxic humans are dangerous and restless.

Animals evolve in intelligence and cognition. Today’s ants are more intelligent than those of the past. Indeed, animals subsist upon human knowledge and awareness; their perception depends on human intellect and consciousness. Psychologically, ants are timid, driven by the fear of hunger, which compels them to store abundant food.

Ants are among the most numerous insects on our planet, due to their complex social behaviour and adaptability to diverse ecosystems. They belong to the order Hymenoptera, which includes bees. Ant societies comprise various castes, including workers, soldiers, winged males, and queens. Workers and soldiers are wingless females who attend to the queen and care for eggs, larvae, and pupae, safeguarding the colony. Winged males, hatched from unfertilised eggs, exist solely to reproduce. Fertilised females raised for queens can fly; after mating, they shed their wings and establish new colonies. Queen ants are typically larger than other colony members.

Each colony begins with a queen, who serves as its reproductive centre. Although people usually perceive ants as non-flying insects, their sexual reproduction often involves an aerial event akin to honeybee mating flights. Globally, ants employ two main mating strategies. The first involves aggregation of males: winged males and virgin queens emerge from the nest and congregate at prominent locations, reducing the likelihood of inbreeding. Mating occurs mid-air, with the male inserting his genital organ (aedeagus) into the female’s reproductive tract, depositing sperm. The queen stores this sperm in a reservoir, using it throughout her life to fertilise eggs. In some species, such as fire ants, the queen mates once before founding a new colony, known as the nuptial flight. Other species, like harvester ants, mate with multiple males before leaving the nest. The second, less common, strategy involves females releasing pheromones to attract males to the ground for mating.

In both strategies, males lose their wings and die shortly after mating. Females also shed their wings but survive to locate a site for a new colony. The queen lays eggs, initially raising a brood of workers unaided. She controls the nest’s location, the sex, and roles of offspring—fertilised eggs become wingless workers or winged reproductive females, while unfertilised eggs become winged males. The queen secretes chemicals inhibiting wing and ovary development in female larvae, producing thousands of workers. Virgin queens are only produced when sufficient workers exist to support colony expansion.

From a psychological perspective, might the predominance of females in ant colonies and the limited role of males solely in reproduction suggest that, if most humans were female with males used merely for reproduction, human societies would benefit from the order and lawfulness observed in ant communities, enhancing survival prospects?

In formal education, girls generally exhibit greater discipline than boys, perform more diligently, and achieve higher grades. Studies consistently show females possess greater self-discipline. Nevertheless, men occupy 95% of senior positions in major government enterprises.

None of these studies address the second part of this question.

Psychologically, could the ants’ reproductive system indicate that reproduction should only be permitted when societal conditions are sufficiently advanced and resourceful, and otherwise be restricted?

The logical and rational answer is affirmative. However, do all individuals think rationally and logically without emotional interference? This remains a challenge, especially as human rights uphold reproductive choice, including the right to decide on unwanted pregnancy termination and preferred family planning methods.

Males lose their wings after mating and die shortly after. Females lose their wings but live on to found colonies. Does this imply that sex is so taxing as to prevent ‘flight’? Could one argue that sex may hinder spiritual ascent in humans, although in human beings, sex is not necessarily a mere physical need but can be spiritual and motivated by love and affection?

While some religious traditions claim that sex is solely for reproduction, in truth, sexual relations are not merely reproductive but can be a joyous and intimate experience between partners. The Bible (Genesis 2:24) states: “Therefore a man shall leave his father and mother and cleave unto his wife, and they shall be one flesh.”

Scientists have found that hormones released during sexual intercourse can enhance spirituality and belief in God. Oxytocin, for example, strengthens social bonds, aids childbirth, and increases religious sentiment.

Sexual relations also help partners connect emotionally, fostering intimacy and trust. Some go further, viewing sex as not merely physical or emotional but as a spiritual experience. Various definitions of spiritual sexuality exist, as with spirituality itself.

Some individuals actively link spiritual sex with religious practices. Studies show that spiritual individuals may engage in sex more frequently. Others view it as a set of spiritual acts, known as tantric sex. Others see it as a means to deepen spiritual connection with a partner.

In certain Hindu traditions, ‘Tantra’ refers to texts exploring the esoteric aspects of religious teaching.

Tantric sex originates from Hindu teachings called Tantra. Its primary aim is a highly focused practice seeking bliss without orgasm. Tantra teaches this as a ritual and method of worship rather than routine sexual activity.

Modern Western ‘Neo-Tantric’ sex diverges significantly, detached from religion. Instead of worship, it helps partners feel closer and intensifies orgasm by delaying it. Many envision spiritual sex incorporating neo-tantric elements.

However, spiritual sex is broader than neo-tantric methods. It may include lighting candles, giving and receiving massages, praying, or any act linking one to spirituality.

Bees

Bees do not spare any plant or flower, eager to collect nectar from all. They dislike any creature approaching while drinking or harvesting nectar. Despite knowing that stinging leads to their death, honeybees sting. The sting parallels ejaculation in men; just as ejaculation induces sleep and relaxation, the bee’s sting results in death. Bees sting out of jealousy, bullying, and aggression. Dominant and authoritarian individuals or those with inferiority complexes behave similarly, disliking others and unable to acknowledge anyone superior or wiser.

Honeybees are selective feeders, unlike chickens that consume anything, even filth. Bees exercise will, choice, and derive pleasure. Honey’s viscous, elastic nature imparts healing qualities.

Mice

Mice reproduce continuously regardless of season or climate. They reach sexual maturity 35 days after birth, with some capable as early as six weeks. Sexing adult rodents is straightforward, though challenging in juveniles. Generally, the ano-genital distance is a reliable method for sex determination in young mice: longer in males with a more pronounced genital papilla and rounded genital slit; males often have well-developed testes, especially in desert species. Females have separate vaginal and urinary openings, with the vaginal orifice situated between the urinary opening and anus. However, the proximity of urinary and vaginal openings makes identification difficult in immature mice.

Mice typically mate at dusk. Females emit pheromones attracting males.