Animals

Brittle star (Ophiuroidea): biology, diversity and ecology Brittle star Brittle stars are echinoderms in the class Ophiuroidea. About 1,500 species live from shallow reefs to deep-sea plains; they have a distinct central disk, five slender arms, varied…

Brontosaurus Large, long-necked sauropod dinosaur of the Late Jurassic. Named in 1879, long treated as a synonym of Apatosaurus, and revived as a distinct genus by a 2015 review. Member of the…

Brontotheriidae (brontotheres): extinct Eocene perissodactyls Brontotheriidae Brontotheriidae, or brontotheres, were large, horned perissodactyl mammals of the Eocene. This article summarizes their anatomy, evolution, distribution, ecology and reasons for ex…

Bronx Zoo: overview, exhibits, history and conservation Bronx Zoo Comprehensive guide to the Bronx Zoo in New York: location, major exhibits, history, conservation work, visitor info and notable facts about one of North America's largest zoos.

Brown bear (Ursus arctos) — overview, biology and conservation Brown bear Large, widespread omnivorous bear of northern Eurasia and North America. Covers taxonomy, behaviour, diet, regional populations, threats, and conservation efforts.

Brown pelican (Pelecanus occidentalis) Brown pelican Large coastal seabird of the Americas known for plunge-diving to catch fish. Covers identification, range, diet, behavior, conservation status, and distinctions from other pelicans…

Brown tree snake (Boiga irregularis): biology, range and invasive impacts Brown tree snake A nocturnal, arboreal colubrid native to parts of Australia, Papua New Guinea and Melanesia, notable as an invasive species that caused severe ecological and economic damage on Gua…

Browser (herbivore feeding type) Browser A browser is an herbivore that eats leaves, shoots and woody plant parts rather than grasses. Covers definition, anatomy and behaviour, ecological role, examples, and differences f…

Brumby — Australia's feral horse Brumby A brumby is a feral horse in Australia. This article explains their origins, physical and social traits, distribution, ecological impacts, management strategies and cultural signif…

Brush-tailed rock-wallaby (Petrogale penicillata) Brush-tailed rock-wallaby A medium-sized rock-wallaby of eastern Australia, adapted to cliffs and rocky outcrops. Faces declines from introduced predators and habitat loss; recovery uses predator control, c…

Bryde's whale: overview, identification, taxonomy, and conservation Bryde's whale Bryde's whales are warm-water baleen whales in a small, closely related species complex; they are recognized by three ridges on the head and face taxonomic, ecological, and conserv…

Bryozoa (moss animals): colony life, structure, and fossil history Bryozoa Bryozoa, or moss animals, are small aquatic colonial invertebrates with lophophores. This article covers their biology, colony structure, reproduction, fossil record, ecology and d…

Budgerigar (budgie): overview, appearance, behaviour and care Budgerigar Compact encyclopedia entry on the budgerigar (budgie): classification, appearance, behaviour, habitat, diet, reproduction, captive care, varieties, health and conservation.

Bufo apolobambicus — a South American toad species Bufo apolobambicus Bufo apolobambicus is a toad of the family Bufonidae found in parts of Bolivia and Peru. It inhabits subtropical and tropical forests and faces population declines primarily from h…

Bufo latastii Bufo latastii is a species of toad in the family Bufonidae native to parts of India and Pakistan. It inhabits temperate woodlands, wetlands and agricultural areas and faces pressur…

Bufo pseudoraddei A true toad of the family Bufonidae known from Pakistan and possibly Afghanistan, inhabiting forests, marshes and agricultural landscapes. Typical toad biology and ecological roles…

Bufoides — genus of true toads Bufoides Bufoides is a small, monotypic genus of true toads in the family Bufonidae, represented by Bufoides meghalayanus from the Khasi Hills region of northeastern India.

Bufonidae (True Toads): Characteristics, Distribution, and Natural History Bufonidae Bufonidae, the true toads, are a widespread family of amphibians noted for warty skin, parotoid toxin glands, egg-strings, varied reproductive modes, and important ecological roles…

Buitreraptor: a small, long-snouted dromaeosaur from Argentina Buitreraptor Buitreraptor is a small dromaeosaurid theropod from Cretaceous Patagonia, notable for its elongated snout, many small unserrated teeth, likely feathers, and placement in a southern…

Bulbuls: an overview of the songbird family Pycnonotidae Bulbul Bulbuls (family Pycnonotidae) are medium-sized passerine songbirds of Africa, the Middle East and southern Asia, common in forests, gardens and scrub. They vary in plumage, voice,…

Bull (intact adult male of domestic cattle) Bull A bull is an uncastrated adult male of domestic cattle (Bos taurus). This article explains its biology, behavior, uses in agriculture, welfare considerations, and cultural signific…

Bull shark (Carcharhinus leucas) Bull shark A compact overview of the bull shark, its appearance, behavior, freshwater tolerance, reproduction, distribution, human interactions, and conservation status.

Bull Terrier A compact, muscular dog breed developed in 19th-century England, known for its distinctive egg-shaped head, short coat, playful temperament, and variety of working and companion ro…

Bulldog (English/British Bulldog) Bulldog A short, muscular dog breed from England known for its wrinkled face, gentle temperament, and distinctive appearance. Commonly kept as a companion breed with specific health and ca…

Bullfinch (Genus Pyrrhula): overview, appearance, distribution and conservation Bullfinch Bullfinches (genus Pyrrhula) are compact finches of the Palearctic region noted for their stout bills, distinctive plumage, and varied conservation status, including a critically e…

American bullfrog (Lithobates catesbeianus): natural history, behavior, and human impacts Bullfrog Comprehensive overview of the American bullfrog, covering identification, life cycle, habitat, diet, invasive spread, human uses, and conservation concerns.

Bullmastiff Large British guardian dog developed from bulldog and mastiff stock in the 19th century; notable for a short fawn or brindle coat, black facial mask, and protective yet affectionat…

Bumblebee (genus Bombus): biology, behavior, and ecological role Bumblebee Bumblebees (genus Bombus) are stout, hairy pollinators found mainly in temperate regions. This article covers their appearance, social life, distribution, ecological importance, an…

Bumblebee bat (Craseonycteris thonglongyai) Bumblebee bat A concise overview of the bumblebee bat — the world’s smallest bat species — covering appearance, habitat, behavior, and conservation status.

Bungarus (kraits): genus of venomous elapid snakes Bungarus Bungarus, commonly called kraits, is a genus of highly venomous elapid snakes native to South and Southeast Asia. Overview of biology, venom, behavior, distribution, and conservati…

Buprestidae — jewel beetles (metallic wood‑borers) Buprestidae Buprestidae, or jewel beetles, are a large family of often metallic, wood‑boring beetles. Larvae tunnel in wood and some species are important forest pests; adults are noted for ir…

Buriolestes: early sauropodomorph from Late Triassic Brazil Buriolestes Basal sauropodomorph Buriolestes schultzi (named 2016) is a small, likely carnivorous dinosaur from the Late Triassic of Brazil, important for understanding the early evolution of…

Burmese python (Python bivittatus) — description, distribution, and behavior Burmese python Large nonvenomous constrictor native to southern and southeast Asia, notable for its patterned skin, strong swimming ability, egg-guarding behavior, and impacts where introduced.

Bush frog Common name for several small, mainly arboreal frogs found chiefly in sub‑Saharan Africa and parts of Asia; applied to unrelated groups that share shrub‑dwelling habits and varied…

Bush rat (Rattus fuscipes) Bush rat A native Australian rodent, the bush rat is a nocturnal omnivore found in coastal and upland habitats; it is common, ecologically important, and sometimes an agricultural pest.

Butterfly: biology, life cycle, evolution, and human interactions Butterfly An accessible overview of butterflies: their classification, anatomy, life cycle, evolution with flowering plants, roles as pollinators, and human interest and conservation.

Butterflyfish (family Chaetodontidae) Butterflyfish Brightly colored, laterally compressed reef fishes of the family Chaetodontidae. Found in tropical oceans, they include about 120 species and are important for reef ecology and the…

Buzzard: overview, biology, and common usage Buzzard A buzzard is a broad-winged bird of prey, usually in the genus Buteo; the term's meaning varies by region and covers several medium-to-large raptors with soaring flight.

Caecilian (order Gymnophiona) Caecilian Caecilians are limbless, elongated amphibians (order Gymnophiona) adapted for a burrowing lifestyle; often mistaken for worms or snakes, they play specialized roles in tropical eco…

Caeciliidae: the common caecilians — burrowing, legless amphibians Caeciliidae Caeciliidae are a widespread family of legless, burrowing amphibians (caecilians) found in the Americas, equatorial Africa and parts of South Asia. They are adapted for a subterran…

Caenagnathasia — a small Asian caenagnathoid oviraptorosaur Caenagnathasia Caenagnathasia is a diminutive Late Cretaceous oviraptorosaur from Asia known from fragmentary jaw material; it illustrates bird-like anatomy and the diversity of small theropods.

Caenorhabditis elegans: a model nematode for genetics and development Caenorhabditis elegans Caenorhabditis elegans is a small, free‑living roundworm extensively used as a model organism to study development, genetics, neurobiology and aging. This article summarizes its bi…

Cage (enclosure for animals and objects) Cage A cage is a framework of bars, mesh or solid panels used to confine, protect, transport or display animals and objects; types, materials and uses vary from pet birdcages to industr…

Caihong — a Late Jurassic paravian with iridescent plumage evidence Caihong Caihong juji is a small, Late Jurassic paravian from China notable for preserved feathers and melanosomes suggesting iridescent coloration and a mix of primitive and bird-like skel…

Caiman A group of New World crocodilians in the family Alligatoridae. Caimans are small-to-large freshwater predators native to Central and South America with six living species and varie…

Cairn Terrier: Origin, Characteristics, Care, and History Cairn Terrier Compact, hardy Scottish terrier breed used for hunting among stone cairns. Overview of appearance, temperament, grooming (hand‑stripping), history, and common roles in modern life.

Calamosaurus (Early Cretaceous theropod) Calamosaurus Calamosaurus is a small, fragmentary theropod known from Lower Cretaceous deposits on the Isle of Wight. Its remains are limited and its precise classification remains uncertain am…

Calcareous sponge (Class Calcarea) Calcareous sponge Calcareous sponges are small marine sponges distinguished by calcium carbonate spicules. This article describes their structure, life cycle, ecology, classification, and how they d…