Pilot whales are cetaceans belonging to the genus Globicephala. There are two extant species, the long-finned pilot whale (G. melas) and the short-finned pilot whale (G. macrorhynchus). The two are not readily distinguished at sea and analysis of the skulls is the best way to tell the difference between them. Between the two species, pilot whales range in waters nearly worldwide with long-finned pilot whales living in cold waters and short-finned pilot whales living in tropical and subtropical waters. Pilot whales are among the largest of the oceanic dolphins, exceeded in size only by the killer whale. They and other large members of the dolphin family are also known as blackfish.
Pilot whales are primarily squid eaters, but will feed on fish as well. They are also highly social and studies suggest that both males and females remain in their mothers' pods, an unusual trait among mammals, also found in certain killer whale communities. Short-finned pilot whales are also one of the few mammal species where females go through menopause and post-reproductive females may contribute to the survival of younger members of their pods. Pilot whales are notorious for stranding themselves on beaches, and are among the most common cetacean stranders. Several theories have been proposed to account for this behavior. The status of both species is not understood and they have been subject to direct and indirect catches by fisheries. Whalers in a few countries continue to hunt pilot whales.
Whale (origin Old English hwæl from Proto-Germanic *hwalaz) is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to the suborder Odontoceti (toothed whales). This suborder also includes the sperm whale, killer whale, pilot whale, and beluga whale. The other Cetacean suborder, Mysticeti (baleen whales), comprises filter feeders that eat small organisms caught by straining seawater through a comblike structure found in the mouth called baleen. This suborder includes the blue whale, the humpback whale, the bowhead whale and the minke whale. All cetaceans have forelimbs modified as fins, a tail with horizontal flukes, and nasal openings (blowholes) on top of the head.
Whales range in size from the blue whale, the largest animal known to have ever existed at 30 m (98 ft) and 180 tonnes (180 long tons; 200 short tons), to various pygmy species, such as the pygmy sperm whale at 3.5 m (11 ft). Whales collectively inhabit all the world's oceans and number in the millions, with annual population growth rate estimates for various species ranging from 3% to 13%.