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Animal facts

Discover the remarkable lives of animals, one fact at a time.

Sperm whale

  • The sperm whale has the largest brain of any animal, weighing about 8 kg.
  • Sperm whales sleep in short naps, hanging almost upright in the water.
  • Their clicks are among the loudest sounds made by any animal.

Spiders

  • Spiders are arachnids rather than insects.
  • All produce silk, but not all build prey-catching webs.
  • The number of eyes varies between species.

Squirrel

  • There are more than 270 species of squirrel in the world, including tree squirrels, ground squirrels, chipmunks, marmots, prairie dogs and flying squirrels.
  • Squirrels are among the few wild animals that will take food from people's hands. Related profile: Wild animals.
  • The smallest squirrel is the African pygmy squirrel, which is only about 7-10 centimetres long and weighs about 10-15 grams.

Starfish

  • Starfish are not fish; they are echinoderms, related to sea urchins.
  • There are about 1,900 known species of sea stars.
  • Sea stars have no brain and no blood.

Stingray

  • Stingrays have no bones in their bodies: their skeleton is made of flexible cartilage, like the material in our ears and nose.
  • Many stingray species live alone and meet only to breed.
  • Stingrays feed on crustaceans, small fish, snails, clams, shrimps and other small animals.

Sumatran tiger

  • Stripes are an individual signature: camera traps allow researchers to recognise the same tiger in different images without capturing it.
  • Water does not stop it: the Sumatran tiger swims well and crosses forest rivers.
  • Males often have long hair framing the cheeks, a typical feature of Sumatran tigers.

Swallow

  • There are about 90 species of swallows and martins around the world.
  • Barn swallows usually live about 2-5 years in the wild.
  • Swallows are built to catch insects in flight, with a slim body and long, pointed wings that give them great agility and endurance.

Swan

  • The swan has a large, strong bill and a long neck and is famous for its graceful movements on the water.
  • A swan has about 25,000 feathers.
  • True swans belong to the genus Cygnus. Examples include the mute swan (Cygnus olor), trumpeter swan (Cygnus buccinator) and black swan (Cygnus atratus). The coscoroba swan belongs to a different genus, Coscoroba.

Swift fox

  • Its name refers to its speed: the swift fox can run at about 60 km/h.
  • It is about the size of a small domestic cat.
  • Swift foxes use dens all year, not only for raising pups.

Swordfish

  • Adult swordfish have no scales and no teeth.
  • Swordfish have no pelvic fins.
  • A special heater organ keeps the swordfish's eyes and brain warm.