Animals

Shrew (Soricidae): small insectivorous mammals Shrew Overview of shrews (family Soricidae): appearance, physiology, taxonomy, distribution, behaviour, and conservation. Not rodents; widespread insectivores with high metabolisms and e…

Shrew opossum (caenolestids): small insectivorous marsupials of the Andes Shrew opossum Shrew opossums (caenolestids) are small, shrew-like marsupials native to high Andean forests and grasslands. This article covers their appearance, behavior, evolution, habitat, and…

Shrike: the predatory passerine often called the 'butcher bird' Shrike Shrikes (family Laniidae) are predatory songbirds known for impaling prey. This article covers appearance, behaviour, taxonomy, distribution, breeding, and human significance.

Shrimp: biology, ecology, uses, and distinctions Shrimp Overview of shrimp—small decapod crustaceans: taxonomy, anatomy, habitats, life cycle, ecological role, culinary use, aquaculture, and key differences from prawns and other similar…

Shuvuuia — small bird-like alvarezsaurid theropod from Late Cretaceous Mongolia Shuvuuia Shuvuuia is a small, bird-like alvarezsaurid theropod from Late Cretaceous Mongolia, known for short, powerful digging forelimbs, likely insectivorous habits, feathered integument,…

Siamang (Symphalangus syndactylus): largest of the lesser apes Siamang The siamang is a black-furred, tailless gibbon native to Malay Peninsula, Sumatra and southern Thailand. Noted for its throat sac, fused toes, loud duets, and threats from habitat…

Siamese cat (Wichian Mat) Siamese cat A distinctive, vocal cat breed originating in Thailand, noted for its blue eyes, point coloration, sociable temperament, and two principal types: traditional (Thai) and modern (wed…

Siamodon — an iguanodontian dinosaur from Thailand Siamodon Siamodon is a genus of iguanodontian ornithopod known from Early Cretaceous deposits in northeastern Thailand. It is represented by fragmentary remains that illuminate Southeast As…

Siamosaurus: Early Cretaceous spinosaurid known from isolated teeth in Thailand Siamosaurus Siamosaurus, an Early Cretaceous spinosaurid from Thailand known only from isolated teeth, points to a fish-eating, partly aquatic lifestyle, but its size and exact classification…

Siberian crane (Grus leucogeranus) Siberian crane A critically endangered, long-distance migratory crane with nearly all-white plumage. Three main populations use distinct flyways between Siberian breeding grounds and wintering we…

Siberian Husky — origins, appearance, behavior, and uses Siberian Husky A medium-sized Arctic sled dog bred by the Chukchi for endurance and speed. Covers appearance, temperament, history, working roles, care needs, and distinguishing traits.

Siberian roe deer (Capreolus pygargus) Siberian roe deer A medium-sized deer of northeastern Asia, the Siberian roe deer occupies varied habitats across Siberia, Mongolia, Central Asia and East Asia and is notable for seasonal breeding a…

Siberian tiger (Amur tiger) — Panthera tigris tigris Siberian tiger The Siberian (Amur) tiger is the largest living tiger, native to the Russian Far East, parts of China and the Korean peninsula. It is endangered, with several hundred individuals r…

Sicklefin lemon shark (Negaprion acutidens) Sicklefin lemon shark A tropical coastal requiem shark of the order Carcharhiniformes, notable for its sickle-shaped dorsal fins, yellowish coloration, nursery use of shallow waters, and sensitivity to…

Sidewinder rattlesnake (Crotalus cerastes) Sidewinder A small desert-dwelling pit viper known for its lateral, rolling motion across sand. Adapted to arid environments with heat-sensing pits, camouflage, and a distinctive rattle warni…

Sierra newt — a mountain subspecies of the California newt Sierra newt The Sierra newt (Taricha torosa sierrae) is a poisonous newt native to the Sierra Nevada. This article summarizes its appearance, life cycle, habitat, threats, and differences from…

Sigilmassasaurus — Late Cretaceous African theropod known from short neck vertebrae Sigilmassasaurus Sigilmassasaurus is a carnivorous theropod from Late Cretaceous North Africa, known mainly from distinctive short, wide cervical vertebrae; its classification and relation to other…

Sika deer (Cervus nippon) Sika deer Sika deer (Cervus nippon) are medium-sized deer native to East Asia, known for spotted coats, vocalizations, and several distinct subspecies; they have been introduced worldwide an…

Silent dormouse (Graphiurus surdus) Silent dormouse A small, nocturnal African dormouse of the Gliridae family found in parts of central West Africa. Poorly known, likely arboreal and associated with moist lowland forests; threatene…

Silky pocket mouse (Perognathus flavus) Silky pocket mouse Small North American heteromyid rodent with silky fur and fur-lined cheek pouches. Nocturnal seed-eater adapted to arid and semi-arid habitats; closely related to pocket gophers.

Silky shark (Carcharhinus falciformis) Silky shark A comprehensive overview of the silky shark: identification, habitat, behavior, diet, reproduction, and conservation of this widespread pelagic requiem shark.

Silky sifaka (Propithecus candidus) Silky sifaka A rare, white-furred sifaka lemur endemic to northeastern Madagascar, notable for its silky coat, leaping locomotion, small social groups, and critical conservation status.

Silver-haired bat (Lasionycteris noctivagans) Silver-haired bat A small North American insectivorous bat with frosted fur; solitary and migratory, found in forested habitats from Canada through the United States to Mexico and Bermuda.

Silverfish (Lepisma saccharina): appearance, biology, and interactions with people Silverfish Small, wingless insects known for silvery scales and fish-like motion. Overview of appearance, behavior, diet, habitat, evolutionary history, and control in homes and collections.

Simian (Simiiformes): the higher primates — monkeys, apes and humans Simian Simians (infraorder Simiiformes) are the higher primates: Old World and New World monkeys and apes (including humans). This entry covers traits, classification, evolution, distribu…

Sinoceratops — a large centrosaurine ceratopsid from China Sinoceratops Sinoceratops, meaning 'horned face from China', is a large short-frilled ceratopsid known from a partial skull and other fragments; it was the first centrosaurine formally reported…

Sinodelphys — an Early Cretaceous metatherian from China Sinodelphys Sinodelphys is an Early Cretaceous metatherian mammal known from an exceptionally preserved skeleton from the Yixian Formation (Liaoning, China). It informs early metatherian anato…

Sinornithoides — a small troodontid theropod from Early Cretaceous China Sinornithoides Small troodontid dinosaur from the Early Cretaceous of Inner Mongolia, known for its bird-like anatomy and inferred insectivorous diet; important for studies of small theropod and…

Sinornithosaurus: a feathered dromaeosaur from the Lower Cretaceous Sinornithosaurus Small, feathered dromaeosaur first described from the Yixian Formation in China. Fossils preserve plumage and advanced the view that many theropods bore feathers, informing the din…

Sinosauropteryx: Early Cretaceous feathered non-avian theropod Sinosauropteryx Small early Cretaceous theropod from China that preserved filamentous 'protofeathers' and pigment patterns; important for understanding the origin and function of feathers.

Sinosaurus (Early Jurassic theropod) Sinosaurus Sinosaurus, meaning 'Chinese lizard', is an Early Jurassic bipedal theropod known from fossils in China. Noted for paired skull crests and debated classification, it helps illumina…

Sinovenator — a small basal troodontid from the Yixian Formation Sinovenator Sinovenator is a small, birdlike troodontid from the Early Cretaceous Jehol biota of northeastern China, known from two specimens and important for studies of early paravian evolut…

Siphonophore — colonial hydrozoans including the Portuguese man o' war Siphonophore Siphonophores are colonial cnidarians (class Hydrozoa) whose bodies are integrated colonies of genetically identical zooids specialized for feeding, locomotion, reproduction and de…

Siphonops leucoderus (Salvador caecilian) Siphonops leucoderus A concise encyclopedia entry on Siphonops leucoderus, a limbless amphibian of family Caeciliidae from Brazil, covering appearance, habitat, behavior, and conservation consideration…

Sir David's long-beaked echidna (Zaglossus attenboroughi) Sir David's long-beaked echidna A small, little-known long-beaked echidna from the Cyclops Mountains of Indonesian New Guinea, described from a single specimen and named for Sir David Attenborough.

Sirenia (order of aquatic mammals) Sirenia Sirenia are an order of fully aquatic, herbivorous mammals including manatees and the dugong. They are slow-breeding, coastal and riverine animals with distinctive flippers and evo…

Sirenidae — the sirens: aquatic, paedomorphic salamanders Sirenidae Sirenidae (sirens) are an unusual family of aquatic salamanders with external gills and no hind limbs, native to the southeastern United States and parts of northern Mexico. Overvi…

Skate (fish) A flattened, cartilaginous fish of the family Rajidae. Skates are bottom-dwelling relatives of rays, with oviparous reproduction, thorned backs, and more than 200 species worldwide…

Skink (Scincidae): biology, behavior, and natural history Skink Skinks are a diverse family of smooth-scaled lizards (Scincidae) found worldwide. This article outlines their anatomy, behavior, diet, evolution, ecological roles and how they diff…

Skipjack tuna (Katsuwonus pelamis) Skipjack tuna Skipjack tuna is a small, fast-growing tropical tuna species widely caught for canned “light” tuna; known for schooling behavior, global distribution, and importance to fisheries.

Skipper (butterfly) Skippers are stout-bodied butterflies of the family Hesperiidae, known for fast, darting flight, hooked antennae, and diverse life histories. They occur worldwide and include many…

Skua (Stercorarius): aggressive seabirds and kleptoparasites Skua Skua (genus Stercorarius) are robust seabirds known for kleptoparasitism and direct predation. They breed on tundra and islands, migrate widely, and include jaeger species with var…

Skunk (Mephitidae): overview, characteristics and human interactions Skunk Skunks are small to medium-sized mammals known for distinctive coloration and a defensive spray. This article covers appearance, diet, behavior, range, species, and relationships w…

Skye Terrier: history, characteristics, care, and notable examples Skye terrier A medium-length article on the Skye terrier, a Scottish breed from the Isle of Skye: appearance, temperament, origins, uses, care needs, and famous examples such as Greyfriars Bobb…

Sled dog Working dogs bred and trained to pull a sled or sleigh over snow and ice, used historically for transport and today for sport, tourism, search and rescue, and cultural traditions.

Slender loris A small, nocturnal primate of South Asia known for slow, deliberate arboreal movement, strong grasping limbs, large eyes, insectivorous diet, and conservation concerns from habitat…

Slender salamander (genus Batrachoseps) Slender salamander A concise overview of slender salamanders (Batrachoseps): appearance, range, life history, habitat, and conservation. Highlights distinguishing features and ecological role in west…

Sloth: slow-moving arboreal mammals of the Americas Sloth Sloths are slow-moving, tree-dwelling mammals of the superorder Xenarthra found in Central and South America. They are notable for specialized claws, low metabolism, unique fur eco…