Many land animals will dip beneath the waves to catch and eat fish , but the reverse situation can sometimes occur too, as the titan triggerfish demonstrates. The fish, which can grow to a length of 75 centimetres, will sometimes beach itself to feed on crabs walking along the shoreline.

In 2018, on the Red Sea’s Mar Mar Island, Matthew Tietbohl, a coral reef ecologist at King Abdullah University of Science & Technology in Saudi Arabia, was surveying a beach for sea turtle tracks with some colleagues. The team heard loud splashing at …