Each year, grey whales embark on a huge migration, going some 6,000km from their Arctic feeding grounds to the breeding grounds off Baja California, Mexico, and then back again. Rarely do they eat during their time away from the Arctic. This individual though did, though, have a go. It spewed seabed from its mouth after filtering food from the mud. From the boat it was unclear what was happening but from a drone's perspective all became clear.