- Pilot whale
image_width = 250px
regnum =Animal ia
phylum = Chordata
classis =Mammal ia
ordo =Cetacea
familia =Delphinidae
genus = "Globicephala"
range_
range_map_width = 250px
range_map_caption = Green: Long-finned range; Blue: Short-finned.
subdivision_ranks = Species
subdivision = "Globicephala macrorhynchus " "Globicephala melas "The pilot whale is either of two
species ofcetacea n in thegenus "Globicephala". The genus is part of theoceanic dolphin family (Delphinidae) although their behaviour is closer to that of the largerwhale s. The two species are theLong-finned Pilot Whale and theShort-finned Pilot Whale . The two are not readily distinguished at sea and are typically just known simply as Pilot Whales or Calderón in Spanish. They and other large members of the dolphin family are also known as blackfish.Description
Pilot Whales are jet black or a very dark grey colour. The
dorsal fin is set forward on the back and sweeps back. The newborn whale's dorsal fin is flexible at birth so as to facilitate the birthing process. The body is elongated but stocky and narrows abruptly toward the tail fin.The differences in appearance between the long-finned and short-finned pilot whales are quite subtle, and where their distributions overlap it is generally not possible to tell the species apart at sea. On land specimens may be distinguished by the length of flipper, the number of teeth and the shape of the skull: the Short-finned has a more bulbous head particularly in older males; the Long-finned is squarer, and the forehead is more likely to overhang the mouth. "G. macrorhynchus" was described, from skeletal materials only, by
John Edward Gray in 1846. He presumed from the skeleton that the whale had a large beak ("macrorhynchus" inLatin ).Birth weight of calves is roughly 220 lb. (100kg.). Adult males can reach up to 20 feet (6.1 m) and weigh up to 3 tons. Adult females measure up to 16 feet (4.9 m) and weigh up to 1.5 tons.American Cetacean Society Fact Sheet - [http://www.acsonline.org/factpack/PilotWhale.htm Pilot Whale] ] Life span is about 45 years in males and 60 years in females for both species.
Both species live in groups of about 10 to 30 in number on average but some groups may be 100 or more. They are quite active and will frequently lobtail, spyhop and approach boats.
Pilot Whales feed predominantly on squid. As compared to their other tooth-whale relatives they have many fewer teeth; numbering only 30 to 40 as compared to 120 in the bottlenosed dolphin. This is thought to be an adaptation to their squid eating diet.
Population and distribution
Pilot Whales are amongst the most common and widely-distributed of the
marine mammal s in the cetacean order.The Long-finned species prefers slightly cooler waters than the Short-finned and is divided into two populations. The larger group is found in a circumpolar band in the
Southern Ocean running from approximately 20° S to 65° S. It may be sighted off the coasts of Eastern Canada,Chile ,Argentina ,South Africa ,Australia andNew Zealand . There are estimated to be in excess of 200,000 individuals in this group. The second population is much smaller and inhabits the NorthAtlantic Ocean , in a band that runs fromSouth Carolina in the United States across to theAzores andMorocco and its southern edge and from Newfoundland toGreenland , Iceland and northernNorway at is northern. It is also present in the western half of theMediterranean Sea .The Short-finned species is more populous. It is found in temperate and tropical waters of the Indian, Atlantic and Pacific Oceans. Its population overlaps slightly with the Long-finned Species in the western Atlantic. There are 150,000 individuals in the eastern tropical Pacific Ocean. There are estimated to be more than 30,000 animals in the western Pacific, off the coast of Japan.
Both species prefer deep water.
Human interaction
The long-term survival prospects of both species look good. Indeed in its
Red List of Threatened Species theIUCN lists both the Long-finned and Short-finned as "Lower Risk; conservation dependent".The Long-finned Pilot Whale has traditionally been hunted by whalers by the process of "driving" - where many fishermen and boats gather in a semicircle behind a pod of whales, that has been sighted close to shore, and slowly drive them towards a bay. When close enough stones attached to lines from the boats are thrown into the water behind the whales, driving them towards the beach where they become stranded and are slaughtered. This practice was common in both the nineteenth and twentieth centuries. Currently only the
Faroe Islands operates such a cull. There have been kept statistics for the drives in the Faroe Islands for centuries, and in the 1980s around 2,500 individuals were killed each year in this manner, declining in the 1990s to under a thousand.The Short-finned Pilot Whale has also been hunted for many centuries, particularly by Japanese whalers. In the mid-1980s the annual Japanese kill was about 2,300 animals. This had decreased to about 400 per year by the 1990s. Killing by harpoon is still relatively common in the
Lesser Antilles ,Indonesia andSri Lanka . Due to poor record-keeping it is not known how many kills are made each year, and what effect this has on the local population.Both species are also collaterally caught and killed in longline and gill-nets each year.
References
*"National Audubon Society Guide to Marine Mammals of the World" ISBN 0-375-41141-0
*"Encyclopedia of Marine Mammals" ISBN 0-12-551340-2
*"Whales, Dolphins and Porpoises", Mark Carwardine, ISBN 0-7513-2781-6External links
* [http://www.sailhawaii.com/Pilot_whales.html Short-finned Pilot Whales in Hawaii]
Wikimedia Foundation. 2010.