Animals

Heart urchin (Spatangoida) Heart urchin Heart urchins are infaunal echinoids adapted to burrowing in soft sediments; this article summarizes their anatomy, behavior, ecology, taxonomy, fossil record and role in coastal s…

Hectocotylus — the specialized reproductive arm of cephalopods Hectocotylus A hectocotylus is a modified arm in male cephalopods used to transfer spermatophores (packages of sperm) to a female. It varies in form and function across octopuses, squids, cuttl…

Hedgehog — small spiny mammal Hedgehog Overview of hedgehogs: appearance, behavior, diet, distribution, life cycle, interaction with humans and distinctions from similar animals.

Hedylidae — the American moth-butterflies Hedylidae A small, entirely Neotropical family of lepidopterans called American moth-butterflies. Moth-like in appearance, they are a sister group to true butterflies and include the genus M…

Helix (genus of air-breathing land snails) Helix (gastropod) Helix is a genus of large terrestrial pulmonate snails native to Europe and the Mediterranean, known for species like H. aspersa and H. pomatia, edible escargots, distinct reproduc…

Helix pomatia (Roman or Burgundy snail) Helix pomatia Large European land snail species (Helix pomatia), known as the Burgundy or Roman snail. Terrestrial pulmonate, eaten as escargot, with distinctive shell, reproductive behavior, ec…

Helmeted honeyeater (Lichenostomus melanops cassidix) Helmeted honeyeater A critically endangered subspecies of yellow‑tufted honeyeater endemic to Victoria, Australia, with a tiny wild population in Yellingbo and ongoing recovery efforts involving habit…

Hemiphractidae — marsupial and back‑brooding frogs Hemiphractidae Hemiphractidae is a neotropical family of frogs notable for diverse parental care, including dorsal brood pouches and back‑carried eggs. Native to Central and South America, the gr…

Herbivore (plant-eating animal) Herbivore Animals that primarily eat plant material. Overview of definitions, feeding categories, adaptations, ecological roles, examples and distinctions from omnivores and carnivores.

Herd (collective group of animals) Herd A herd is a social grouping of animals—most often hoofed mammals—whose members move and behave together through simple local interactions. The concept is used in ecology, animal hu…

Hereford cattle: breed overview, characteristics, history and uses Hereford (cattle) Encyclopedic entry on Hereford cattle covering origin, appearance, global distribution, breeding (including Polled Herefords), management, uses in beef production and role in cross…

Hermit crab Hermit crabs are decapod crustaceans that protect their soft abdomens by occupying empty gastropod shells. They show unique shell‑use behaviour, varied habitats, and important ecol…

Hermit Thrush (Catharus guttatus) Hermit thrush A medium-sized North American thrush with a reddish tail and flute-like song; common in forests and the official state bird of Vermont.

Hermitage cats: the resident cats of the State Hermitage Museum Hermitage cats Resident felines at the State Hermitage Museum in Saint Petersburg, Russia, kept as vermin control and cultural tradition for centuries; cared for by staff, volunteers and donors.

Heron (Ardeidae): biology, behaviour, and conservation Heron Herons are long-legged wading birds of the family Ardeidae, including egrets and bitterns. This article outlines their anatomy, behaviour, classification, habitats, and conservatio…

Herrerasaurus: an early carnivorous dinosaur from the Late Triassic Herrerasaurus Herrerasaurus, a small bipedal carnivore from northwestern Argentina, is among the earliest known dinosaurs. It sheds light on early dinosaur anatomy, ecology, and classification d…

Herring: biology, behavior, culinary uses and cultural significance Herring Overview of herring: small schooling fish important in marine ecosystems, their biology and migration, culinary uses, and cultural references including the 'red herring' trope.

Herring gull (Larus argentatus) — description, distribution and behaviour Herring gull Large, familiar gull of northern and western Europe. Covers identification, range, habitat, diet, breeding, migration, human interactions and taxonomy with key distinctions and beh…

Herveo plump toad (Orsornophryne percrassa) Herveo plump toad A small, stocky Andean toad endemic to Colombia; inhabits montane forests and high-altitude grasslands and is threatened by habitat loss and other pressures.

Hesperornis: a toothed, flightless marine bird of the Late Cretaceous Hesperornis Hesperornis is an extinct genus of large, flightless, toothed aquatic birds from the Upper Cretaceous. Noted for its diving adaptations and historical importance to avian paleontol…

Heterodontosauridae: the different‑toothed early ornithischians Heterodontosaur Small, early ornithischian dinosaurs known for mixed tooth types and tusk‑like canines. Lived from the Late Triassic through the Early Cretaceous, with debates over their exact rel…

Heterodontosaurus Small Early Jurassic ornithischian from South Africa with three distinct tooth types—incisiform, caniniform tusks, and cheek teeth—important for studies of diet and early dinosaur…

Heteromyidae — kangaroo rats, kangaroo mice and pocket mice Heteromyidae Heteromyidae is a family of mainly granivorous New World rodents (kangaroo rats, kangaroo mice, pocket mice) adapted to arid and semiarid habitats, notable for cheek pouches, hoppi…

Heteroptera: the true bugs Heteroptera Heteroptera, commonly called true bugs, are a diverse group of Hemiptera with hemelytra and piercing-sucking mouthparts. They include aquatic and terrestrial species, important as…

Hexacorallia: six-fold symmetric anthozoans including stony corals and anemones Hexacorallia Hexacorallia is a subclass of Anthozoa characterized by sixfold symmetry; it includes stony corals, sea anemones and related groups, important for reefs, marine biodiversity and pa…

Highland cattle Hardy Scottish cattle with long horns and a double coat. Raised mainly for beef, suited to wet, windy climates, used in conservation grazing, small-scale farming and cultural herit…

Himalayan cat: appearance, origins, care, and breed status Himalayan cat A long‑haired, blue‑eyed color‑point cat developed from Persian and Siamese stock; known for distinctive markings, calm temperament, grooming needs, and mixed breed recognition.

Himalayan goral (Naemorhedus goral) Himalayan goral A compact, goat-like mammal of the Himalayan region; the Himalayan goral is a member of the Caprinae subfamily, adapted to steep rocky slopes and facing habitat pressures across it…

Himalayan monal (Lophophorus impejanus) Himalayan monal A brightly colored pheasant of the Himalayan region, the Himalayan monal (Lophophorus impejanus) inhabits montane forests and alpine meadows; it is Nepal's national bird (danphe) a…

Hippopotamidae: the hippopotamus family Hippopotamidae Hippopotamidae are large semiaquatic even-toed ungulates native to Africa, represented today by two species. This entry summarizes their traits, evolution, conservation, and differ…

Hippopotamus (Hippopotamus amphibius): biology, behavior, and conservation Hippopotamus Large semi‑aquatic African mammal, second only to elephants among land mammals in size. Overview of appearance, behavior, habitat, social life, and conservation challenges.

Hoatzin: the leaf-eating bird of Amazonian wetlands Hoatzin The hoatzin (Opisthocomus hoazin) is a distinctive South American bird known for its leaf-based diet, enlarged fermenting crop, wing-clawed chicks and uncertain evolutionary relati…

Hog badger (Arctonyx collaris): appearance, range, and conservation Hog badger The hog badger (Arctonyx collaris) is a stout mustelid native to central and southeast Asia. This article covers its appearance, behavior, distribution, taxonomy, threats and conse…

Hog deer (Hyelaphus porcinus): a small Asian deer Hog deer A compact overview of the hog deer (Hyelaphus porcinus), its appearance, behaviour, range across South and Southeast Asia, ecology, conservation issues and notable facts including…

Hogna: large wolf spiders of the family Lycosidae Hogna Hogna is a genus of large, ground-dwelling wolf spiders (Lycosidae). Species are active hunters, often burrowing or hiding in leaf litter, and play an important role as insect pred…

Holocephali: chimaeras, fossil record, anatomy, and ecological role Holocephali Holocephali are a subclass of cartilaginous fishes represented today by chimaeras. This article explains their anatomy, long fossil record, origins, ecology, and how they differ fr…

Holostei: gars, bowfin, and primitive ray-finned fishes Holostei Holostei are a small clade of ray-finned fishes including gars and the bowfin. Few species survive today, but the group has a long fossil history and distinctive anatomy important…

Homalocephale — a small flat-skulled pachycephalosaur Homalocephale Homalocephale, a small pachycephalosaurid dinosaur with a thick but flattened skull, is known from Late Cretaceous deposits and informs how dome shapes varied among horned and thic…

Homing pigeon: breed, navigation, history and uses Homing pigeon Homing pigeons are selectively bred rock pigeons renowned for returning to a single home loft over long distances; used for racing, message-carrying and research, they navigate usi…

Homotherium — the scimitar‑toothed saber‑tooth cat Homotherium Extinct genus of machairodontine saber‑toothed cats known as scimitar‑toothed cats, widespread in the Pliocene–Pleistocene and notable for shorter, blade‑like upper canines and lon…

Honey bee (genus Apis) Honey bee Social flying insects of the genus Apis that produce honey and beeswax, live in perennial colonies, act as important pollinators, and are managed by beekeepers; studied in melittol…

Honeyeater (Meliphagidae): Nectar-feeding Birds of Australasia Honeyeater Honeyeaters are a diverse family (Meliphagidae) of mostly nectar-feeding birds native to Australasia. This article covers their traits, distribution, ecological role, taxonomy and…

Honeyguide (Indicatoridae): wax-eating birds famed for guiding to bee nests Honeyguide Honeyguides are Old World tropical birds (family Indicatoridae) that eat beeswax and larvae, sometimes lead people to bee colonies, and practice brood parasitism; most species occu…

Hooded crow (Corvus cornix) Hooded crow A grey-and-black crow native to parts of Europe and the Middle East. Corvus cornix is an adaptable, omnivorous corvid noted for its distinctive plumage, intelligence, and close rel…

Hooded seal (Cystophora cristata) Hooded seal Arctic pinniped known for the male's inflatable nasal 'hood' and an unusually brief lactation; found in the central and western North Atlantic and closely tied to seasonal sea ice.

Hoof: structure, types, care, and biological role Hoof A hoof is the hardened, keratin-covered tip of a toe in ungulate mammals. This article explains hoof anatomy, types, evolution, functions, common health issues, and basic care prac…

Hoopoe (Upupa epops): description, behavior, distribution and cultural role Hoopoe The hoopoe (Upupa epops) is a crested, insectivorous bird of Afro‑Eurasia, known for its fanlike crown, probing bill, distinctive call, and a long history of cultural symbolism and…

Hornbill (Bucerotidae): Tropical Birds, Behavior, and Conservation Hornbill Hornbills are distinctive tropical birds with large curved bills and often a casque. Found across Africa, Asia and Melanesia, they are important seed dispersers with unique nesting…