An Eden’s whale trap feeding in the Gulf of Thailand. This extraordinary behaviour (where the whale treads water!) is thought to have developed because pollution has made the Gulf of Thailand a hypoxic environment. Sewage outflows from the land have caused all the oxygen in the water to be used up, except at the surface. This means the whale’s fish prey can only live in this surface layer. By treading water and keeping the corners of their mouth below the surface, a flow is created pulling the fish into the whale's mouth. In the panic, some of the fish also seem to jump out the water and into the whale’s mouth!