Animals

Spinosauridae: the spined, semi-aquatic theropod family Spinosauridae Spinosauridae is a group of large carnivorous theropod dinosaurs with elongated skulls, conical teeth and tall neural spines; they show adaptations for fishing and lived in coastal…

Spinosaurus — sail-backed semi-aquatic theropod Spinosaurus Spinosaurus, a large mid-Cretaceous theropod from North Africa, is known for its tall dorsal sail, crocodile-like skull and likely semi-aquatic habits; its size, posture and ecolog…

Spiny dogfish (Squalus acanthias) Spiny dogfish A small, widely distributed temperate shark species known for dorsal spines, schooling behavior, slow reproduction, and significant commercial and conservation interest.

Spiny lobster (rock lobster): biology, behavior, fisheries and conservation Spiny lobster Spiny lobsters (family Palinuridae) are clawless, long‑antennaed crustaceans of warm seas. This article covers their anatomy, life cycle, behaviour, fisheries value and conservatio…

Spiny mouse (genus Acomys) Spiny mouse Small African and Middle Eastern rodents of the genus Acomys, notable for stiff guard hairs, scaled tails and unusual regenerative abilities; of interest in ecology, pet-keeping an…

Spitz (dog) — Characteristics, History and Notable Breeds Spitz (dog) Spitz-type dogs are a group of northern breeds with thick double coats, pointed features and curled tails; they include Arctic working dogs and small companion varieties.

Splendid astrapia (Astrapia splendidissima) Splendid astrapia A medium-sized bird-of-paradise from New Guinea noted for the male's iridescent yellow-green mantle and short white-tipped tail feathers; inhabits montane forests and feeds mainly…

Sponge (Porifera): structure, ecology, and evolutionary significance Sponge Sponge (phylum Porifera) — simple, mostly marine animals with porous bodies, filter-feeding habits, long fossil record, and important ecological roles in aquatic ecosystems.

Spoonbill (wading bird) Spoonbill Spoonbills are large, long-legged wading birds with distinctive spatulate bills. They feed by sweeping their bills through shallow water, nest in colonies, and occur in wetland hab…

Spot-billed pelican (Pelecanus philippensis) Spot-billed pelican Medium-large pelican of South and Southeast Asia, breeding on inland and coastal wetlands. Notable for its spotted bill, colonial tree nests and reliance on healthy shallow waters.

Spotted bass (Micropterus punctulatus): description, distribution, and angling Spotted bass Freshwater black bass native to the Mississippi River basin, commonly called spotted or Kentucky bass. Description, habitat, identification, history, angling notes, and distinction…

Spotted eagle ray (Aetobatus narinari) Spotted eagle ray A large, graceful eagle ray with white spots on a dark back, found in tropical and subtropical coastal waters worldwide. Feeds on benthic invertebrates and is notable in ecotourism…

Springbok (Antidorcas marsupialis): description, behavior, and significance Springbok The springbok is a medium-sized antelope of southern Africa known for leaping ‘pronking’, its striking coloration, and its cultural importance as South Africa’s national animal.

Springtail (Collembola): small soil arthropods with a springing tail Springtail Springtails (Collembola) are tiny wingless hexapods that live in moist soils and leaf litter. They feed on fungi and detritus, play key roles in decomposition, and are distinct fro…

Squamata: the scaled reptiles — lizards, snakes and worm lizards Squamata Squamata is the largest order of living reptiles, including lizards, snakes and amphisbaenians. This article covers their defining features, diversity, evolution, reproduction and…

Squealer (Animal Farm) Squealer is a fictional pig in George Orwell’s Animal Farm who functions as the farm’s propagandist; he illustrates techniques of political persuasion, censorship, and the manipula…

Squid: Biology, behavior, and human interactions Squid Overview of squid biology, anatomy, behavior, diversity and human uses. Covers locomotion, feeding, reproduction, notable species, predators, fisheries, research and conservation c…

Squirrels: Overview, types, behavior, and interactions Squirrel A concise encyclopedia entry on squirrels (family Sciuridae): their biology, major groups, diet, distribution, predators, relationships with humans, and conservation notes.

Squirrel monkey (Saimiri) — small New World primates Squirrel monkey Small, arboreal New World primates of the genus Saimiri found in Central and South America; social, diurnal, frugivorous-insectivorous, with long tails and distinctive alarm calls.

Sri Lankan junglefowl (Gallus lafayettii) Sri Lankan junglefowl Endemic galliform bird of Sri Lanka, the national bird. Distinctive, colorful male, ground-dwelling omnivore, culturally important and related to other junglefowl species with cons…

Staffordshire Bull Terrier A compact, muscular British dog breed known for its strength, affectionate temperament with people, and controversial history stemming from early bloodsports.

Stag beetle (Lucanidae) Stag beetle Stag beetles (family Lucanidae) are a diverse group of saproxylic beetles noted for the enlarged jaws of males. This article covers their appearance, life cycle, behavior, range, a…

Starling (Sturnidae): biology, behavior, distribution, and human interactions Starling Starlings (family Sturnidae) are small to medium passerine songbirds known for iridescent plumage, gregarious flocks, vocal mimicry and widespread introductions that affect native…

Staurikosaurus — an early Late Triassic theropod from Brazil Staurikosaurus Staurikosaurus is a small, early theropod dinosaur from the Late Triassic of Brazil, known from limited remains and valued for what it reveals about early dinosaur evolution and fo…

Staurozoa — the stalked jellyfish: biology, classification and ecology Staurozoa Staurozoa are a small class of stalked jellyfish in the phylum Cnidaria. They live attached to substrates, lack a free-swimming medusa stage, and occur mainly in cold coastal water…

Stegoceras — thick‑shelled pachycephalosaur of Late Cretaceous North America Stegoceras Stegoceras was a small bipedal pachycephalosaur known for its thick domed skull. Fossils from western North America inform debates about its diet, behavior, and the function of its…

Stegodon: an extinct genus of proboscideans Stegodon Stegodon is an extinct genus of proboscideans known from the late Miocene to the late Pleistocene, notable for large body size, tusks, and island dwarf descendants; fossils are fou…

Stegosauria: plated dinosaurs of the Jurassic and Early Cretaceous Stegosauria Stegosauria were herbivorous, armored dinosaurs in Thyreophora noted for rows of plates and tail spikes. Lived from the Upper Jurassic to the Lower Cretaceous; plate function remai…

Stegosaurus — the plated Late Jurassic herbivore Stegosaurus Stegosaurus is a well-known Late Jurassic herbivorous dinosaur from western North America, notable for paired back plates and tail spikes. Its anatomy, discovery, behavior, and sci…

Steller's sea cow (Hydrodamalis gigas) Steller's sea cow Extinct large marine herbivore of the North Pacific, discovered in 1741 and driven to extinction within decades by hunting and ecological change.

Stenonychosaurus Stenonychosaurus is a small troodontid dinosaur from Late Cretaceous Alberta, known from fragmentary remains. Modern revisions have separated it from the historic genus Troodon and…

Stenopterygius — a streamlined Lower Jurassic ichthyosaur Stenopterygius Stenopterygius was a dolphin‑shaped marine reptile of the Lower Jurassic known for its narrow flippers, streamlined body, and fossils preserving live‑birth embryos; common in Germa…

Steppe bison (Bison priscus): Pleistocene grazing megafauna Steppe bison Bison priscus, commonly called the steppe bison or steppe wisent, was an extinct Pleistocene bison that ranged across Eurasian steppes, Beringia and North America; known from fossi…

Steropodon — an early Australian monotreme from the Lower Cretaceous Steropodon Steropodon is an early monotreme known from opalized jaw fossils in Australia; it reveals tooth-bearing, egg-laying mammals in the Mesozoic and informs monotreme evolution and Gond…

Stick insect (Phasmatodea): camouflage, biology and diversity Stick insect Stick insects (order Phasmatodea) are cryptic, primarily herbivorous insects that mimic sticks or leaves. This article summarizes their form, life cycle, behavior, distribution, ta…

Stickleback (Gasterosteidae): biology, distribution, and behavior Stickleback Overview of sticklebacks (family Gasterosteidae): distinctive anatomy, reproduction and nesting, habitat and distribution, and their role in research and ecosystems.

Stingray (Myliobatoidei): biology, behaviour and human interactions Stingray Comprehensive overview of stingrays (Myliobatoidei): anatomy, senses, feeding, reproduction, habitats (marine and freshwater), defensive sting and venom, human interactions and con…

Stoat (Mustela erminea): the short-tailed weasel and ermine Stoat Small predatory mammal of the Mustelidae family, known as the short-tailed weasel or ermine in winter. Noted for seasonal fur change, fierce hunting, food caching, and cultural use…

Stone dormouse (Graphiurus rupicola) Stone dormouse A small nocturnal rodent of the Gliridae family found in rocky habitats of southern Africa. Overview of appearance, behavior, distribution, and conservation considerations.

Stork (Ciconiidae): Biology, Behavior, Species and Conservation Stork Overview of storks (family Ciconiidae): their anatomy, feeding, migration, nesting, notable species, cultural significance and conservation issues.

Stotting (pronking): the high jump display of antelopes and ungulates Stotting A locomotor display in some ungulates—especially gazelles—where an animal springs with all four feet off the ground. Covers form, proposed functions and observed significance.

Strabomantidae — Neotropical terrestrial frogs with direct development Strabomantidae Strabomantidae are a family of terrestrial frogs from South America characterized by direct development: eggs hatch into miniature froglets. They are diverse, often endemic, and fa…

Strepsiptera — twisted‑wing parasitic insects Strepsiptera Strepsiptera are a small order of endoparasitic insects (about 600 species) known for extreme sexual dimorphism and a unique life cycle that parasitizes other insects including pla…

Strepsirrhini — the wet-nosed primates Strepsirrhini Strepsirrhini are one of two primate suborders, including lemurs and lorises. They retain a wet rhinarium, strong olfaction and many nocturnal adaptations; most species live in Mad…

Striped Dolphin (Stenella coeruleoalba) Striped dolphin A medium-sized oceanic dolphin with distinctive flank stripes, found in temperate and tropical seas worldwide; known for fast, social behavior and vulnerability to bycatch and poll…

Striped hyaena: description, behaviour, range and cultural role Striped hyaena Overview of the striped hyaena (Hyaena hyaena): appearance, behaviour, distribution, conservation status and relationships with people across Africa and Eurasia.

Struthiomimus — an ostrich-like ornithomimid dinosaur Struthiomimus Struthiomimus was a lightly built, fast-running ornithomimid from the Late Cretaceous of North America, notable for long legs, a toothless beak and likely feathers; fossils are com…

Stud (animal): male breeding animals and stud farm management Stud (animal) A stud is a male animal used for breeding. Covers definitions, species terms, selection and management, stud farms, historical role, welfare concerns and common distinctions.