Animals

Sloth bear (Melursus ursinus) Sloth bear A medium-sized bear of the Indian subcontinent, the sloth bear is insectivorous, shaggy-furred, and adapted to feeding on termites and ants; it faces habitat loss and historical pe…

Slow loris (Nycticebus): nocturnal strepsirrhine primates of Asia Slow loris Nocturnal primates of the genus Nycticebus found across South and Southeast Asia, notable for slow, deliberate movement, a varied diet including gums and nectar, and pressing conse…

Slug: shell-less gastropods, biology, ecology and distinctions Slug An overview of slugs—land and marine shell-less gastropods—covering anatomy, behavior, evolution, ecological roles, impacts on gardens and agriculture, and distinctions from snails…

Small white (Pieris rapae) Small white Pieris rapae, the small white or cabbage white, is a common butterfly in the Pieridae family known for its pale wings, association with brassicas, and widespread distribution due t…

Small-eared dormouse (Graphiurus microtis) Small-eared dormouse Small-eared dormouse (Graphiurus microtis), a small nocturnal rodent of the Gliridae family, native to southern and eastern Africa; arboreal, omnivorous, and generally of low conse…

Smalleye hammerhead (Sphyrna tudes) Smalleye hammerhead Small coastal hammerhead shark of the western Atlantic, often golden-bronze in color; lives in shallow, muddy bays and estuaries and is vulnerable to coastal fishing and habitat ch…

Smallmouth bass (Micropterus dolomieu): description, range, and importance Smallmouth bass Overview of the smallmouth bass, a North American freshwater game fish: taxonomy, appearance, life history, habitat, range and introductions, angling significance, and ecological i…

Smilodon — the saber-toothed cat of the Pleistocene Smilodon Smilodon, a genus of saber-toothed felids from the Americas, includes three well-known species. This article summarizes their anatomy, fossil record, likely behavior, and scientifi…

Smooth snake (Coronella austriaca) Smooth snake A small, non-venomous European colubrid, the smooth snake is secretive and largely restricted to heathland and open scrub; it feeds chiefly on other reptiles and is protected in pa…

Snail (gastropod): biology, diversity and human uses Snail Snails are coiled‑shell gastropods found in marine, freshwater and terrestrial habitats. This article outlines their anatomy, evolution, ecology, notable species, and interactions…

Snail kite (Rostrhamus sociabilis): a specialist wetland raptor Snail kite A wetland raptor of the Americas, the snail kite (Rostrhamus sociabilis) is narrowly adapted to feed on freshwater snails. Overview of its appearance, behavior, range, and conserva…

Snakes (Serpentes): anatomy, behavior, distribution, and evolution Snake Snakes are legless carnivorous reptiles of the clade Serpentes. This article summarizes their anatomy, senses, habitat, evolution, size range, and relationships with people and eco…

Snares penguin (Eudyptes robustus) Snares penguin A crested penguin endemic to The Snares, New Zealand; notable for its yellow head crest, restricted range, and breeding on offshore islands. Closely related to other Eudyptes pengu…

Snoopy — The Peanuts Beagle and Cultural Icon Snoopy Snoopy is Charlie Brown’s imaginative beagle from Charles M. Schulz’s Peanuts. Famous for his alter egos, oversized doghouse interior, and appearances in comics, TV specials and me…

Snow leopard (Panthera uncia): description, habitat, and conservation Snow leopard Large mountain cat of Central and South Asia, Panthera uncia (snow leopard) is adapted to cold, rugged landscapes. This article covers appearance, behaviour, taxonomy, threats and…

Snowy owl (Bubo scandiacus) Snowy owl Large white Arctic owl adapted to tundra life, noted for lemming hunting, ground nesting, periodic southward irruptions, and cultural prominence (for example, Hedwig in Harry Potte…

Socorro dove (Zenaida graysoni) — island species extinct in the wild Socorro dove A small dove once native to Socorro Island, Mexico. Extinct in the wild since the 1970s, it survives in captive breeding programs aimed at future reintroduction and habitat restora…

Sole (flatfish) Sole (fish) Sole is a name for various flattened demersal fish—chiefly members of Soleidae—valued in fisheries and cuisine. Includes Dover (common) sole and other similar flatfish worldwide.

Solenodon — the slotted-tooth mammals Solenodon Solenodons are rare, nocturnal insectivorous mammals with grooved incisors and a venom-delivery system. Two species survive in the Caribbean; the group is a relict lineage illumina…

Solifugae (camel spiders, wind scorpions, sun spiders) Solifugae Solifugae are an order of arachnids often called camel spiders or wind scorpions. Mostly found in arid regions worldwide, they are fast, non-venomous predators with powerful jaws a…

Somniosidae — the sleeper sharks Somniosidae Somniosidae, commonly called sleeper sharks, are slow-moving deepwater sharks in the order Squaliformes known for low activity, cold-water habitats, long lifespans, and vulnerabili…

Song thrush (Turdus philomelos) — description, behavior and range Song thrush A medium-sized European songbird (Turdus philomelos) known for its repeated musical phrases, spotted underparts and snail‑smashing habit; widespread but locally declining.

Songbird (Passeri): the singing suborder of passerine birds Songbird Songbirds (suborder Passeri) are a diverse clade of passerine birds known for their complex vocal organ and learned songs. They evolved in the Australo‑Papuan region and now includ…

Sooglossidae (Seychelles frogs): overview, biology and conservation Sooglossidae Sooglossidae are a tiny family of leaf‑litter frogs best known from the Seychelles with unusual reproductive modes, restricted ranges and an evolutionary history tied to ancient Go…

Sooty mangabey (Cercocebus atys): natural history and conservation Sooty mangabey West African monkey (Cercocebus atys). Social, omnivorous, and an important seed disperser. Faces habitat loss and hunting; notable as a natural host of simian immunodeficiency vir…

South Asian River Dolphin (Platanista gangetica) South Asian river dolphin Freshwater dolphin of South Asia (Platanista gangetica), with Ganges and Indus subspecies; adapted to turbid rivers with reduced eyesight and echolocation; vulnerable from habitat…

Southern cassowary (Casuarius casuarius) Southern cassowary Large flightless bird of New Guinea and northeast Australia, notable for its casque, two wattles and role as a major seed disperser in tropical rainforest ecosystems.

Southern corroboree frog (Pseudophryne corroboree) Southern corroboree frog A critically endangered, brightly striped frog endemic to alpine bogs of Australia's Kosciuszko National Park. Threats include disease, habitat change and small population size.

Sow bug (woodlouse): terrestrial isopod and detritivore Sow bug Sow bugs (woodlice) are small terrestrial isopods. This article covers their biology, anatomy, behavior, ecological role, differences from similar arthropods, and interactions with…

Spadefoot toad Common name for several fossorial frogs and toads adapted to dry, sandy habitats; noted for a keratinized digging spade, explosive breeding in temporary pools, and rapid, sometimes…

Spaniel (dog): breeds, history, characteristics, and care Spaniel Spaniels are a group of gundogs bred to flush game. This article covers origins, typical appearance and temperament, common breeds, roles, training, health, and key distinctions.

Spanish Fighting Bull (Toro Bravo): breed, history and cultural role Spanish Fighting Bull The Spanish Fighting Bull (Toro Bravo) is a heterogeneous Iberian cattle population bred for bravery, strength and stamina and historically managed on extensive dehesa estates acro…

Sparassodonts — extinct South American metatherian predators Sparassodont Sparassodonts were an extinct order of carnivorous metatherian mammals native to South America. They evolved specialized teeth and skulls for meat-eating and occupied apex predator…

Sparrow (genus Passer) — Old World passerine birds Sparrow Small, social Old World passerine birds of the genus Passer (family Passeridae). Includes the familiar house sparrow; often found near people, feeding on seeds and insects; conserv…

Sparrowhawk (Accipiter nisus): small Eurasian woodland raptor Sparrowhawk A compact encyclopedia entry on the Eurasian sparrowhawk (Accipiter nisus): identification, behaviour, distribution, breeding, conservation history and cultural associations.

Species: definition, classification, and biological importance Species An overview of the biological concept of species: definitions, taxonomic context, history, methods of identification, examples, and why species matter for biodiversity and conserva…

Speciesism: concept, history, ethical debates, and real-world examples Speciesism Speciesism is prejudice or discrimination based on species membership. This article explains the concept, origins, philosophical arguments, examples, and distinctions from related…

Spectacled bear (Tremarctos ornatus): the Andean bear Spectacled bear The spectacled bear, or Andean bear, is South America’s only bear species. Known for its variable facial markings, arboreal habits and cultural importance, it faces habitat loss an…

Spectacled caiman (Caiman crocodilus) Spectacled caiman A medium-sized crocodilian native to Central and South America, the spectacled caiman is named for a bony ridge between its eyes; it is adaptable, widespread, and ecologically impo…

Spectral bat (Vampyrum spectrum): the largest New World carnivorous bat Spectral bat Overview of the spectral bat (Vampyrum spectrum): appearance, range, hunting behavior, diet, reproduction, and conservation, with distinctions from Old World ‘false vampires’.

Sphenodontia (Rhynchocephalia): the tuatara lineage Sphenodontia Sphenodontia, also called Rhynchocephalia, are an ancient group of lepidosaur reptiles best known today for the tuatara of New Zealand. This article summarizes their traits, histor…

Sphingidae — hawk moths, sphinx moths and hornworms Sphingidae Sphingidae is a family of moths known for rapid flight, hovering, and long proboscises. About 1,450 species worldwide, important as pollinators, pests, and subjects of ecological s…

Sphinginae — a subfamily of hawkmoths Sphinginae Sphinginae is a subfamily of large, fast-flying hawkmoths (Sphingidae). This article summarizes their appearance, life cycle, notable species, ecological roles, taxonomy and conser…

Sphynx cat A domestic cat breed recognized for its near hairlessness, warm, supple skin, active temperament, and specific care needs including bathing, sun protection, and attentive breeding.

Sphyrna — genus of hammerhead sharks Sphyrna Sphyrna is the larger of the two hammerhead shark genera. Members are recognizable by their flattened 'hammer' heads (cephalofoils); several species inhabit warm coastal waters and…

Spider: biology, behavior, diversity, and ecological role Spider Concise encyclopedia entry on spiders (order Araneae): anatomy, silk and venom, hunting strategies, diversity, distribution, ecological importance and notable facts.

Spider monkey (genus Ateles) Spider monkey Arboreal New World monkeys of the genus Ateles, known for long limbs and a prehensile tail; frugivorous, socially complex, and important seed dispersers found from southern Mexico…

Spinner dolphin (Stenella longirostris) Spinner dolphin A small, acrobatic oceanic dolphin of tropical offshore waters worldwide, known for its spinning leaps, social groups, nocturnal feeding and varied conservation concerns across pop…