Baleen whales filter seawater through bristly plates, trapping krill and small fish inside their mouths.

The longer version

Fringed plates hang in rows from the upper jaw, built from the same protein as hair and nails. Rather than catching prey one at a time, an animal takes an enormous mouthful of water and food together, then pushes the water out while fibres hold back everything too large to slip through.

Throat pleats expand hugely during the gulp, so a single lunge can engulf a volume approaching the animal's own mass. From an energetic standpoint this works only where prey gathers densely, explaining why the largest bodies gather in polar seas and follow migrating shoals.

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.