Animals

A.P. Indy: Champion American Thoroughbred and Influential Sire A.P. Indy A.P. Indy (1989–2020) was an American Thoroughbred racehorse, 1992 Horse of the Year, Belmont and Breeders' Cup Classic winner, and a highly influential sire whose offspring shaped…

Aardonyx — a basal sauropodomorph from the Early Jurassic Aardonyx Aardonyx is a genus of basal sauropodomorph dinosaur from Early Jurassic South Africa, noted for transitional anatomy between bipedal ancestors and quadrupedal sauropods.

Aardvark (Orycteropus afer): nocturnal African insectivore and burrower Aardvark Aardvark (Orycteropus afer) is a nocturnal, burrowing African mammal that feeds mainly on ants and termites. Sole living member of Tubulidentata, noted for digging adaptations, tub…

Aardwolf (Proteles cristata): the termite-eating hyena Aardwolf Small nocturnal African carnivore in the hyena family that feeds mainly on termites. Notable for its long sticky tongue, burrowing habits, strong scent-marking and generally solita…

Abalone — Haliotis sea snails: shells, biology, culinary use, and conservation Abalone Abalone are marine gastropod mollusks (genus Haliotis) prized for their iridescent shells and edible muscle. This article covers their anatomy, distribution, uses, aquaculture, and…

Abelisaurus: a fragmentary abelisaurid theropod from South America Abelisaurus Abelisaurus is a poorly known genus of abelisaurid theropod from Late Cretaceous South America. Known from skull fragments, it is the type genus of Abelisauridae and informs Gondwa…

Abrictosaurus — Early Jurassic heterodontosaurid from southern Africa Abrictosaurus Abrictosaurus was a small bipedal ornithischian from the Lower Jurassic of southern Africa, often considered the most basal heterodontosaurid; notable for its tusks, distinctive ch…

Acanthocephala — thorny‑headed (spiny‑headed) parasitic worms Acanthocephala Acanthocephala are obligate parasitic worms characterized by a spiny, eversible proboscis. Found in aquatic and terrestrial food webs, they have complex life cycles and are closely…

Acanthodii: extinct spiny fishes and early jawed vertebrates Acanthodii Acanthodii, or spiny sharks, were extinct early jawed fishes (Silurian–Permian) with fixed fin spines and mixed bony/cartilaginous traits. Their fossils illuminate early gnathostom…

Acantholipan: armored ankylosaurian dinosaur from Mexico Acantholipan Acantholipan is a genus of large, armored, quadrupedal ankylosaurian dinosaur known from fragmentary Late Cretaceous fossils in Mexico, notable for its osteoderms and regional impo…

Acanthopholis — an armored Early Cretaceous dinosaur Acanthopholis Acanthopholis is a genus of armored, quadrupedal herbivorous dinosaur known from fragmentary Early Cretaceous remains found in southern England; its skin armour and spikes illustra…

Acanthostega, an Early Devonian fishapod Acanthostega Acanthostega was an aquatic, limb‑bearing vertebrate from the Late Devonian. Its fossils illuminate the transition from lobe‑finned fishes to early tetrapods and reveal limbs adapt…

Surgeonfishes and Tangs (Acanthuridae): Reef Grazers with Blade-like Caudal Spines Acanthuridae Surgeonfishes and tangs (Acanthuridae): reef fishes notable for blade-like caudal spines, vivid colors, and important algal-grazing roles that help maintain coral reef health.

Acanthuroidei Acanthuroidei is a group of perciform fishes that includes surgeonfishes, moorish idols, luvars and relatives; reef-associated, laterally compressed, ecologically important grazers…

Acarina (Acari): Mites and Ticks — Biology, Diversity and Impact Acarina Acarina (Acari) are the mites and ticks, a diverse group of arachnids found in almost every habitat. This article summarizes their biology, evolution, ecology, economic effects and…

Acarology: the scientific study of mites and ticks Acarology Acarology is the branch of zoology that investigates mites and ticks—their biology, classification, ecology, medical and agricultural impacts, and methods used to identify and mana…

Accipitridae: overview of diurnal birds of prey Accipitridae Accipitridae is a large, cosmopolitan family of diurnal birds of prey including hawks, eagles, kites, harriers and Old World vultures; they vary widely in size, diet, behavior and…

Acherontia atropos — Death's‑head Hawkmoth Acherontia atropos Acherontia atropos is a large hawkmoth notable for the skull-like thoracic mark, its honey‑robbing habit, strong flight and a prominent place in folklore, natural history and popul…

Acherontia lachesis — The Asian Death's-head Hawkmoth Acherontia lachesis Acherontia lachesis is a large sphingid moth of the Oriental region, noted for a skull-like thoracic mark, honey‑robbing behavior, and distinctive squeaking adults.

Achillobator — a large Cretaceous dromaeosaurid from Mongolia Achillobator Achillobator is a large dromaeosaurid theropod from the Upper Cretaceous of Mongolia, known from a single specimen. It had a prominent sickle claw, likely feathers, and highlights…

Aconoidasida — a class of blood-infecting apicomplexan parasites Aconoidasida A class of Apicomplexa comprising blood parasites such as Plasmodium, Babesia and Theileria. Characterized by a reduced conoid, complex vector-borne life cycles, and major medical…

Acrididae — the short-horned grasshopper family Acrididae Acrididae is the largest family of short-horned grasshoppers, containing most Caelifera species including all locusts. They have short antennae, abdominal tympana, hemimetabolous d…

Acrocanthosaurus: the high‑spined theropod of the Lower Cretaceous Acrocanthosaurus Acrocanthosaurus was a large high‑spined theropod from Lower Cretaceous North America, notable for tall neural spines, robust forelimbs, and its likely placement among the carcharo…

Actias luna (Luna moth) Actias luna Actias luna, commonly called the luna moth, is a large pale-green silkmoth native to North America, known for its long hindwing tails, striking eyespots, and short-lived, nonfeedin…

Actinopterygii — the ray-finned fishes Actinopterygii Actinopterygii, or ray-finned fishes, are the dominant class of vertebrates. This article summarizes their anatomy, diversity, evolutionary history, habitats, and importance to eco…

Adamantisaurus — a fragmentary titanosaur from the Late Cretaceous of Brazil Adamantisaurus Adamantisaurus is a little-known titanosaurian sauropod known only from a handful of tail vertebrae from the Adamantina Formation; it highlights challenges in classifying fragmenta…

Adapiformes: early fossil primates of the Eocene–Miocene world Adapiformes Adapiformes are an extinct group of early primates known from Eocene–Miocene fossils. They inform primate evolutionary history, paleobiogeography, and debates over strepsirrhine an…

Adasaurus — a small dromaeosaur from the Late Cretaceous Gobi Desert Adasaurus Adasaurus is a small dromaeosaurid theropod known from late Cretaceous deposits in Mongolia; notable for its sickle-shaped toe claw and fragmentary fossil record.

Adder (Vipera berus): the common European viper Adder Vipera berus, the adder, is a small venomous viper found across Europe and into Asia. This article covers identification, behavior, venom effects, reproduction, range, and conserva…

Adenomus — a small genus of Sri Lankan true toads Adenomus Adenomus is a small genus of true toads endemic to Sri Lanka, containing three species. One species, Adenomus kandianus, was rediscovered in 2009 after more than a century without…

Adenorhinos — a monotypic viper genus (Adenorhinos barbouri) Adenorhinos Adenorhinos is a little-known, monotypic genus of venomous viper endemic to the Uzungwe–Ukinga highlands of south‑central Tanzania. The single species is rare and ground‑dwelling.

Adephaga — a suborder of predatory beetles Adephaga Adephaga is a major beetle suborder that includes ground, tiger, diving and whirligig beetles. Predominantly predatory, it comprises many species important in ecosystems and with d…

Adrastus (genus of click beetles) Adrastus (genus) Adrastus is a genus of click beetles in the family Elateridae, established in 1829; members share the characteristic click mechanism and have ecological roles ranging from soil-dwe…

Aedes (mosquito): description, biology, public health significance Aedes Aedes is a genus of primarily tropical mosquitoes, many species of which can transmit human viral diseases. This article summarizes identification, life cycle, distribution, and pu…

Aedes aegypti — the yellow fever mosquito: biology, distribution, and public health Aedes aegypti Aedes aegypti is a small, primarily urban mosquito that transmits dengue, chikungunya, yellow fever and other viruses. Covers identification, life cycle, habitat, disease risk and…

Aegean cat A naturally occurring domestic cat from the Cyclades islands of the Aegean Sea, known for its fishing habits, sociable temperament, and role both as companion and as free-roaming p…

Aegyptosaurus — African titanosaurian sauropod Aegyptosaurus Aegyptosaurus, a titanosaurian sauropod from the Upper Cretaceous of northern Africa, is known from early 20th‑century discoveries (many since lost) and is important for understand…

Aeolosaurus — Late Cretaceous titanosaur from South America Aeolosaurus Aeolosaurus is a genus of aeolosaurine titanosaurian sauropod known from multiple individuals in Late Cretaceous Argentina, noted for distinctive tail vertebrae and limited skull m…

Aepyornis — extinct elephant bird of Madagascar Aepyornis Aepyornis was a genus of giant, flightless ratite birds native to Madagascar, notable for enormous eggs and a late Holocene extinction likely linked to human arrival and habitat ch…

Affenpinscher — small German toy dog breed Affenpinscher A small, sturdy toy dog from Germany known for its monkey-like face, wiry coat and lively temperament. Bred originally as a ratter, now kept mainly as companion dogs with specific…

Afghan Hound An ancient sighthound breed from Afghanistan, distinguished by a long silky coat, independent temperament, and high speed. Historically a hunter, now kept as companion, show dog, a…

African buffalo (Syncerus caffer) African buffalo Large, powerful African bovine (Syncerus caffer) known as the Cape buffalo; a social grazer with distinctive horns, strong herd defenses, ecological importance, and variable conser…

African bullfrog (Pyxicephalus adspersus) African bullfrog Large, robust frog of southern and eastern Africa known as the African or pixie frog; notable for deep burrowing, strong jaws, parental care and wide seasonal activity in savannas…

African bush elephant (Loxodonta africana) African bush elephant Large savanna elephant native to Sub-Saharan Africa. Overview of appearance, range, behavior, threats from poaching and habitat loss, and conservation measures.

African elephant: overview, biology, behavior and conservation African elephant Large African mammals of the genus Loxodonta: two species, distinctive anatomy, social systems and conservation challenges including poaching and habitat loss.

African fish eagle (Haliaeetus vocifer) African fish eagle A large African sea-eagle known for its white head, loud call and fish-centered diet; widespread near lakes and rivers and a national symbol in several African countries.

African forest elephant (Loxodonta cyclotis) African forest elephant A forest-dwelling African elephant adapted to rainforest life in the Congo Basin; smaller, with straighter tusks and vital ecological roles. Taxonomy, characteristics, threats, and…

African golden cat (Caracal aurata): description, habitat, and conservation African golden cat Medium-sized wild cat of equatorial African rainforests. Varied coat colors, elusive behavior, and declining populations due to habitat loss and hunting; closely related to the car…