Animals: fun facts and quiz

Animals with backbones fall into five classic groups: mammals, birds, reptiles, amphibians and fish. But most animal species are invertebrates, like insects.

Key fact
About 97% of animal species have no backbone.

Mammals are warm-blooded, have hair or fur, and feed their young on milk. They range from tiny bats to the blue whale.

Key fact
The platypus is a mammal that lays eggs.

The blue whale is the largest animal known ever to have lived, up to about 30 m long. The cheetah is the fastest land animal, sprinting at around 100 km/h.

Key fact
A blue whale’s heart can weigh around 180 kg.

Insects have six legs and three body parts. They’re the most varied animals on Earth, with about a million named species.

Key fact
Spiders aren’t insects: they have eight legs.

Many animals travel huge distances each year. The Arctic tern flies from the Arctic to the Antarctic and back, around 70,000 km a year.

Key fact
Some birds navigate using Earth’s magnetic field.

Crows solve puzzles and use tools, octopuses open jars, and dolphins recognise themselves in mirrors.

Key fact
New Caledonian crows make hooked tools from twigs.

Many animals hide in plain sight. Chameleons and cuttlefish change colour, stick insects look like twigs, and some harmless snakes copy venomous ones.

Key fact
Cuttlefish can change colour in under a second.