The blue whale – the largest living animal on the planet – can eat half a million calories in a single titanic gulp. It accelerates to high speeds and lunges into a swarm of tiny krill. It opens the world’s biggest mouth, which expands like a balloon to swallow up to 110 tonnes of water. The mouth closes, and the tongue pushes the water against bristly plates called baleen, which filter out the krill.

The blue whale’s skull is specially adapted to allow it to engulf large volumes of water. If you push against your chin, nothing happens because the two halves of your lower jaw are firmly fused together at the front. That’s not the case for the blue