Blue whales are the largest animals known to have lived, bigger than any dinosaur yet found.

The longer version

Body size at sea meets different limits than on land. Water supports most of the mass, so no skeleton has to carry tonnes against gravity, and heat loss falls away once an animal grows large enough to hold warmth. Food arrives shoaling in dense patches, and filtering huge volumes rewards an enormous mouth.

Nothing here punishes bulk the way terrestrial life does. The largest known land animals are dwarfed by comparison, and because big warm-blooded bodies need enormous quantities of prey each day, the giants depend on concentrations of small organisms rather than on hunting anything comparable to themselves.

Where this entry sits

Oceans and Sea Life looks at the salt water that covers most of the planet, from crashing waves and tides to the darkest deep-sea trenches. Expect notes on coral, fish, whales, sharks, jellyfish, shells, and the strange creatures that live far below the surface. The full list sits on the Oceans and Sea Life page, where every entry is listed in order.