Pilot whale
Pilot whales are cetaceans belonging to the genus Globicephala. The two extant species are the long-finned pilot whale (G. melas) and the short-finned pilot whale (G. macrorhynchus). The two are not readily distinguishable at sea, and analysis of the skulls is the best way to distinguish between the species. Between the two species, they range nearly worldwide, with long-finned pilot whales living in colder 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 orca. They and other large members of the dolphin family are also known as blackfish.
Pilot whales feed primarily on squid, but will also hunt large demersal fish such as cod and turbot. They are highly social and may remain with their birth pod throughout their lifetime. Short-finned pilot whales are one of the few mammal species in which females go through menopause, and postreproductive females continue to contribute to their pod. Pilot whales are notorious for stranding themselves on beaches, but the reason behind this is not fully understood, although marine biologists have shed light on the discovery it is due to the mammals inner ear (their principal navigational sonar) being damaged from noise-pollution in the ocean, such as from cargo ships or military exercises.[2] The conservation status of short-finned and long-finned pilot whales has been determined to be least concern.
The animals were named "pilot whales" because pods were believed to be "piloted" by a leader.[3][4] They are also called "pothead whales" and "blackfish". The genus name is a combination of the Latin word globus ("round ball" or "globe") and the Greek word Kephale ("head").[3][4]
Pilot whales are classified into two species; the long-finned pilot whale (Globicephala melas) and the short-finned pilot whale (G. macrorhynchus) The short-finned pilot whale was described, from skeletal materials only, by John Edward Gray in 1846. He presumed from the skeleton that the whale had a large beak. The long-finned pilot whale was first classified by Thomas Stewart Traill in 1809 as Delphinus melas.[5] Its scientific name was eventually changed to Globicephala melaena. Since 1986, the specific name of the long-finned pilot whale was changed to its original form melas.[6] Other species classifications have been proposed but only two have been accepted.[7] There exist geographic forms of short-finned pilot whales off the east coast of Japan,[8] which comprise genetically isolated stocks.[9]
Fossils of an extinct relative, Globicephala baereckeii, have been found in Pleistocene deposits in Florida.[3] Another Globicephala dolphin was discovered in Pliocene strata in Tuscany, Italy, and was named G. etruriae.[3] Evolution of Tappanaga, the endemic, larger form of short-finned pilots found in northern Japan, with similar characteristics to the whales found along Vancouver Island and northern USA coasts,[10] have been indicated that the geniture of this form could be caused by the extinction of long-finned pilots in north Pacific in the 12th century where Magondou, the smaller, southern type possibly filled the former niches of long-finned pilots, adapting and colonizing into colder waters.[11]
