Cetorhinus maximus
The basking shark is the second-largest fish in the sea, a slow-moving filter feeder that swims open-mouthed through plankton blooms. It can sieve thousands of litres of water an hour and carries an enormous oily liver for buoyancy. Historically hunted for oil, it is Endangered in the northeast Atlantic and still at risk from ship strikes, entanglement, and illegal finning.