What is the blobfish?

“My lack of muscle mass makes me sad.”

The blobfish is adapted to live in water 0.8 kilometres (half a mile) deep. At this depth the pressure is 80 times higher than at sea level and a normal gas-filled swim bladder is almost useless. Most creatures at these depths give up trying to swim entirely and simply walk or flop along the seabed. But flopping requires more energy and the blobfish is much too lazy for that. It has traded almost all its muscle mass for a jelly that is just slightly less dense than water. This allows it to coast just above the ocean floor. It doesn’t chase its prey, but simply swallows anything that’s slow or careless enough to get in the way of its mouth. Unusually for a fish, the female ‘sits’ on her eggs, instead of just abandoning them after laying. This is probably to protect them from being eaten by other blobfish in the vicinity.