Animals

Alpine marmot (Marmota marmota) Alpine marmot A large, social mountain rodent of central and southern Europe, known for communal burrows, loud alarm calls and long winter hibernation; its range reflects survival since the Ice…

Alpine newt (Ichthyosaura alpestris) Alpine newt A medium-sized European newt species, Ichthyosaura alpestris is an amphibian with seasonal aquatic breeding, distinctive male breeding colours, and wide but locally threatened habi…

Altiphrynoides: Ethiopian highland toads Altiphrynoides Altiphrynoides is a small genus of toads endemic to the highlands of south-central Ethiopia, notable for egg-laying reproduction and conservation concerns from habitat loss.

Altispinax — a fragmentary high-spined Early Cretaceous theropod Altispinax Altispinax is a little-known Early Cretaceous theropod from Sussex, England, recognized for tall neural spines and a complicated taxonomic history tied to other Wealden theropods.

Alvarezsaurus: a small Late Cretaceous theropod from Argentina Alvarezsaurus Alvarezsaurus is a small bipedal theropod from Upper Cretaceous Argentina (≈86–83 Ma). A basal alvarezsaur with cursorial hindlimbs, it helps document the transition to the short-a…

Alxasaurus — an Early Cretaceous therizinosaur Alxasaurus Alxasaurus, meaning "Alxa lizard", is a small therizinosaur theropod from the Early Cretaceous of Inner Mongolia known from several partial skeletons; it sheds light on the transit…

Amami rabbit (Pentalagus furnessi) Amami rabbit A rare, primitive rabbit species endemic to two small Japanese islands; notable for its dark fur, isolated lineage, nocturnal habits, and endangered status.

Amargasaurus — small crested sauropod of the Early Cretaceous Amargasaurus Amargasaurus, a relatively small dicraeosaurid sauropod from Early Cretaceous Argentina, is notable for paired elongated neural spines along its neck and back and well-preserved fo…

Amargosa toad — an endemic desert amphibian Amargosa toad Overview, biology, habitat, taxonomy and conservation of the Amargosa toad (formerly Bufo nelsoni), a narrow‑ranged amphibian of the Amargosa River basin and nearby springs.

Amazonsaurus — a rebbachisaurid sauropod from the Early Cretaceous Amazonsaurus Amazonsaurus, meaning 'Amazon lizard', is a medium-sized rebbachisaurid sauropod from the Early Cretaceous of South America, known from fragmentary remains and notable for its long…

Amber-colored salamander (Hynobius stejnegeri) Amber-colored salamander A small, endemic Japanese salamander in the family Hynobiidae. Lives in forested streamside habitats, breeds in water, and faces population pressure from habitat loss and alteratio…

Amblypygi — whip spiders and tailless whip scorpions Amblypygi Amblypygi are an order of arachnids known as whip spiders or tailless whip scorpions. Harmless to people, they are nocturnal, flattened predators found in warm, humid habitats worl…

Ambulocetus — an early amphibious whale Ambulocetus Ambulocetus was a semi-aquatic early cetacean from the early Eocene whose anatomy links terrestrial mammals to modern whales, known from fossils found in what is now Pakistan.

American badger (Taxidea taxus): natural history, behaviour, and role in grassland ecosystems American badger A compact encyclopedia entry on the American badger (Taxidea taxus): appearance, range, digging adaptations, diet, behaviour, ecological importance, conservation and distinctions f…

American bison: biology, ecology, history, and significance American bison Overview of the American bison (Bison bison), its biology, habitat, historical decline and recovery, ecological role, cultural importance, and distinctions from other ‘buffalo’ spe…

American black bear (Ursus americanus) American black bear Comprehensive overview of the American black bear: identification, range, behaviour (including hibernation), diet, reproduction, interactions with people, and conservation and mana…

American Bobtail (cat breed) American Bobtail A North American cat breed noted for its naturally short "bobbed" tail caused by a dominant mutation; robust, adaptable, and recognized by major cat associations for companionship…

American Cocker Spaniel Compact, affectionate sporting dog breed known for its silky coat, expressive eyes, and history as a hunter of woodcock; now popular as a companion, show dog, and versatile working…

American crocodile (Crocodylus acutus) American crocodile Coastal crocodile of the Americas, noted for its narrow, pointed snout, saltwater tolerance, and presence from southern Florida and the Caribbean into northern South America. Conse…

American crow (Corvus brachyrhynchos) American crow A widespread North American corvid noted for glossy black plumage, social intelligence, adaptability to towns and farms, omnivorous diet, and a conservation status of Least Concern…

American Curl — Cat Breed Overview American Curl Domestic cat breed noted for distinctive backward-curling ears; occurs in long- and shorthaired varieties. Affectionate, adaptable, and generally healthy, with moderate grooming an…

American Eskimo Dog — Breed overview, history, characteristics and care American Eskimo Dog A compact, white Spitz-type companion breed from German roots, known as the 'Eskie'. Covers appearance, temperament, history, sizes, care, health and suitability for families and a…

American Foxhound A scent hound developed in the United States for fox hunting and pack work; noted for endurance, a clear baying voice, a lean athletic frame, and a friendly, energetic temperament.

American Hairless Terrier A small American terrier breed naturally hairless or coated; energetic, intelligent, and often chosen by people with allergies. Covers appearance, origins, temperament, care, and n…

American lion (Panthera atrox): Pleistocene predator of North America American lion Large extinct felid of Pleistocene North America, known from La Brea and other sites; related to Eurasian cave lions and notable for its great size, debated taxonomy, and extinctio…

American lobster (Homarus americanus): biology, fishery and conservation American lobster The American lobster is a large northwest Atlantic crustacean prized by fisheries. This article explains its appearance, life cycle, habitat, commercial importance, and management…

American Pharoah: 2015 Triple Crown and Breeders' Cup Classic Champion American Pharoah American Pharoah, foaled 2012, swept the 2015 American Triple Crown and won the Breeders' Cup Classic the same year, becoming the first to capture the modern 'Grand Slam' and earni…

American Pit Bull Terrier: origin, traits, temperament and modern role American Pit Bull Terrier Overview of the American Pit Bull Terrier: appearance, history from British blood-sports to modern companionship, temperament, care, uses, controversies, and how training and socia…

American plaice: biology, habitat, fisheries and conservation American plaice American plaice (Hippoglossoides platessoides) is a northwest Atlantic flatfish. This article summarizes its appearance, behavior, range, diet, fisheries importance and current con…

American robin (Turdus migratorius) American robin A widespread North American thrush known for its orange breast, ground-feeding habits and spring song; overview of identification, range, breeding, diet, predators and conservation…

American Shorthair (cat): history, characteristics, and care American Shorthair A compact overview of the American Shorthair: its origins as a working ship cat, physical and temperament traits, history of breed development, care needs, and distinctions from si…

American spadefoot toads (Scaphiopodidae) American spadefoot toads A small family of North American burrowing frogs (Scaphiopodidae) noted for a keratinous hind-foot 'spade', vertical pupils, explosive breeding in ephemeral pools and rapid tadpole…

American Staffordshire Terrier A medium-sized, muscular dog breed developed from 19th‑century bull-and-terrier crosses. Bred as working companions, they are now kept as family pets, show dogs, and working partne…

American toad (Anaxyrus americanus) American toad A common North American toad found in eastern U.S. and Canada. Overview of appearance, life cycle, habitat, subspecies, ecological role, threats, and taxonomic notes.

Ameridelphia — historical grouping of New World marsupials Ameridelphia Ameridelphia: a traditional taxonomic grouping for New World marsupials—chiefly opossums and shrew opossums—comprising Didelphimorphia and Paucituberculata; its unity is debated by…

Amietophrynus — African true toads (genus) Amietophrynus Amietophrynus is a genus of African true toads, separated from Bufo after taxonomic revisions. They are terrestrial amphibians with glandular, warty skin, widespread ecological rol…

Amniote — Vertebrates Defined by the Amniotic Egg Amniote Amniotes are tetrapod vertebrates whose embryos develop with extraembryonic membranes (the amniotic egg), enabling a fully terrestrial life history; groups include mammals, birds a…

Amolops himalayanus — a Himalayan torrent frog Amolops himalayanus A stream-dwelling frog of the genus Amolops found in the Himalayan region; adapted to fast-flowing waters, important as an insect predator and water-quality indicator.

Ampedus: a genus of click beetles Ampedus Ampedus is a large genus of click beetles (family Elateridae). Members are known for the click mechanism, often colorful patterns, saproxylic larvae, and roles in forest ecosystems…

Ampharos — Electric-type Pokémon (Generation II) Ampharos Ampharos is a Generation II Electric-type Pokémon nicknamed the Lighthouse Pokémon. It evolves from Mareep → Flaaffy and can Mega Evolve into an Electric/Dragon form when holding A…

Amphibian: biology, life cycle, evolution and conservation Amphibian Overview of amphibians (class Amphibia): major groups, anatomy, life cycle, fossil origins, diversity, habitats and modern conservation challenges.

Amphicoelias: a sauropod from the Morrison Formation Amphicoelias Amphicoelias was a Late Jurassic diplodocoid sauropod from the Morrison Formation of Colorado, noted for moderately large size and a controversial fragmentary specimen once interpr…

Amphipod (Amphipoda): biology, diversity and ecological roles Amphipod Amphipods are a diverse order of mostly small, carapace-less crustaceans found in marine, freshwater, cave and terrestrial habitats; many are scavengers or detritivores and importa…

Amphisbaenia (worm lizards): burrowing squamates Amphisbaenia Amphisbaenians, or worm lizards, are a distinct suborder of Squamata adapted for a fossorial (burrowing) lifestyle. This article summarizes their traits, diversity, evolution, ecol…

Amphiuma — elongated aquatic salamanders of the family Amphiumidae Amphiuma Amphiuma is a small genus of large, eel-like aquatic salamanders native to the southeastern United States, notable for reduced limbs with 1–3 toes and very large genome sizes among…

Ampullariidae (apple snails): biology, distribution, and human interactions Ampullariidae Ampullariidae, known as apple or mystery snails, are large freshwater snails with dual respiration, an operculum, and diverse roles as aquarium pets, food, and invasive species wor…

Amur leopard (Panthera pardus orientalis): status, biology, and conservation Amur leopard The Amur leopard is a critically endangered subspecies native to the Russian Far East and northeastern China. This article reviews its appearance, habitat, behavior, threats, and c…

Anaconda (Green Anaconda, Eunectes murinus) Anaconda A large, semi-aquatic South American boa (Eunectes murinus). Non-venomous constrictor, among the heaviest and one of the longest snakes; adapted to rivers, swamps and flooded fores…