Pilot whales are large dolphins with a markedly round forehead. They were named after their reputation for leading fishermen to good fishing grounds for octopus. There is one population living in the northern hemisphere. In the southern hemisphere, there are several including one by Antarctica. Just like killer whales, pilot whales live in close family groups of 20 to 100 animals. They hunt mostly squid. Pilot whales sometimes strand in massive numbers. Sightings of groups of pilot whales migrating through the North Sea appear to be increasing in the past few years. The most recent pilot whale beaching was in May 2006 on Schiermonnikoog.