Long-finned pilot whale
Long-finned pilot whale. Source: Encyclopedia of Life
The long-finned pilot whale (scientific name: Globicephala melas) is one of two species in the genus Globicephala. The pilot whale is so named because when swimming, the groups of about 15 to 20 whales are often led by a single whale, the pilot. This marine mammal is a member of the family Delphinidae (Dolphins and Porpoises), part of the order of cetaceans.
Because of its gregarious nature and ability to be easily trained, this species is often seen in captivity. In fact, the pilot whale has been trained by the US Navy to find lost military equipment at great depths in the ocean.
Like its brother species, the short-finned pilot whale, this species has a very specialized function on its skin. In order to keep microorganisms and other barnacles from growing on their skin, these two species secrete an enzymatic gel. This gel acts to break down any carbohydrates or proteins (the backbones of microorganisms) before the microorganisms can become established exosymbionts.
 Long-finned pilot whale. Source: Robin Baird/Encyclopedia of Life
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Data Deficient |
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Scientific Classification Kingdom: Animalia (Animals) |
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Common names long-finned pilot whale |
Contents
Physical Description
In the dolphin family, the long-finned pilot whale is second only to the Orca in size. Along with the related short-finned pilot whale, this species was once called a 'pothead', as the bulbous head was thought to resemble a black cooking pot by the early whalers that first encountered the species. The Latin name of this genus, Globicephala , meaning globe head also refers to its bulb shape of the head. The stocky body is black or dark grey in colour with a white stripe passing diagonally behind the eye, a greyish area on the belly, and an anchor-shaped grey patch on the chin. As the common name of this species suggests, the sickle-shaped (hook-shaped) pectoral fins (flippers) are very long. This species also has a single blowhole. The range of this species and the short-finned pilot whale overlap in some areas, and it can be very difficult to distinguish between the two, particularly as it is often difficult to see the flippers. This species has teeth on both the upper and lower jaws.
This species exhibits sexual dimorphism (one sex larger than the other). Males can grow to a maximum of 7.6 meters or possibly even more. Females can measure up to 5.8 meters or more. Males weigh up to 2300 kg and females up to 1300 kg.
The skin of pilot whales resists microorganisms thanks to microscopic pores and nanoridges, surrounded by a secreted enzymatic gel which denatures proteins and carbohydrates.
Reproduction
Female mature sexually at age six to seven, with males not reaching sexual maturity until about 12 years. As result, there is an excess of mature females and the species is undoubtedly polygynous, which means that one male mates with many females. The males may compete for mates with fights involving butting, biting and ramming. Mating can also involve some of these activities, and some females carry scars from bites inflicted by males during the breeding season. The adults mate in February and March in warm water, and the young are born in cooler water, between July and October, 15 to 16 months later. The young, when born, are toothless and reported as a brownish to tan-gray colour, and are nursed for about 20 months. The whole reproductive cycle is deduced to be some 40 months. Thus, each adult female probably raises one calf about every three years. Calves are generally 1.8 meters long at birth, and have a body mass of approximately 102 kilograms.
The calf nurses for up to 22 months, with some evidence for longer lactation and extensive mother calf bonds. Most calves are born in the summer, although some calving occurs throughout the year. Some females have been observed to have calves when they are as old as 35 years, and they may continue to lactate as late as 51. This evidence suggests that females may nurse their last calf until puberty of the calf (up to 10 years in males).
Lifespan
The age of pilot whales are determined by counting growth-layers in the dentine of the teeth. Deposition of dentine (the hard, cement-like tissue beneath the enamel), however, ends with complete filling of the pulp-cavity at ages of 10 to 20 years. Cement layers continue to be laid down but are very narrow, allowing less accurate age determination.
Behavior
This species is exceptionally social, and typically travels in groups called pods of between 10 and 50, and sometimes as many as 100 individuals. Long-finned pilot whales are highly active, and can dive for up to 10 minutes to depths of up to 600 meters.
They are not particularly friendly with ships and do not ride the bow waves of vessels. They have an inborn fear of the Orca and will come into shallow water and beach themselves if necessary in order to escape. No instances have been reported of Killer whales associated with pilot whales either inshore or offshore during the summer. Long-finned pilot whales, it appears, remain in the pod in which they were born for their entire lives.
Also, they use echolocation to help them locate a food source. The bulbous forehead houses the pilot's melon, core organ of its sonarlike echolocation system. They are known to dive to depth of 600 metres or more during tests and also when pursuing squid.
The pilot whale is said to be equally as intelligent as the bottlenose dolphin, and does quite well in captivity. In fact, the U.S. Navy has trained this species to recover lost marine equipment at considerable depths in the ocean. A dominant adult serves as the pilot or pod leader. Occasionally these groups socialize with the Common Bottlenose Dolphins and Risso's dolphin. An adult whale needs about 50 kilograms of food a day, which consists chiefly of cephalopods and to a lesser degree of fish. Pilot whales typically take several breaths before diving for a few minutes.
Pods of the Long-finned pilot whale are often seen rafting or resting in a group, a further manifestation of their highly social behaviour. Another exhibition of the species social behaviour is their susceptiblity to herding, a trait that is used in the Faroes and other locations to achieve mass slaughter of many individuals. Long-Finned Pilot Whales are very active and can often be seen lobtailing, tail-slapping and spyhopping. The younger individuals also breach, but this behaviour is relatively uncommon for adults. Long-finned Pilot Whales often are found stranded on beaches; however, because they have strong family bonds, when one animal strands, the remainder of the pod tends to stay near the stranded member, and not infrequently mass strandings may ensue.
Distribution
The distribution of this species is limited to the cooler water of the globe including Antarctica (Large Marine Ecosystem), Belgian Exclusive Economic Zone, Mediterranean Sea, North Sea, Northwest Atlantic, and Subantarctic Waters. The northern and southern populations do not meet, mix, and interbreed because they are separated by a wide band of warm tropical water.
Three subspecies are recognized in some classifications: G. m. melas in the North Atlantic, G. m. edwardii in the southern hemisphere, and an un-named subspecies in Japanese waters (extinctsince the 8th-12th century AD).
Distribution of long-finned pilot whale in the world. Source: IUCN
Habitat
The typical temperature range for the species is 0 - 25°C. The Alboran Sea is one of the most important areas for this species in the Mediterranean (Cañadas and Sagarminaga 2000); in this area, the average depth of encounters was about 850 m (ranging from 300 to 1800 m), reflecting the distribution of their preferred diet, pelagic cephalopods. However, the Long-finned polot whale experinces mortality from Moroccan and Spanish driftnet fisheries in the Alboran. Around the Faroe Islands, tracking studies show a preference for waters over the border of the continental shelf. In addition, this species typically prefers cold, deep, offshore waters.
Food Habits
The diet of the long-finned pilot whale consists mostly of squid, however, they will also eat small medium-sized fish such as macherel, and cod. The average amount of food ingested at a meal is about 14 kg (30lb). They use echolocation to help them locate a food source. The bulbous forehead houses the pilot's melon, core organ of its sonarlike echolocation system. They are known to dive to depth of 600 meters (1967 ft.) or more during tests and also pursuing squid. This dolphin will follow their prey inshore and into continental shelf waters during the summer and autumn.
Conservation Status
The long-finned pilot whale is a UK Biodiversity Action Plan priority species. Under the Wildlife and Countryside Act of 1981, it is illegal to intentionally kill, injure, capture or harass whales and dolphins in UK waters. Commercial trade of this species is prohibited. This species is listed on the IUCN Red List as Data Deficient.
Threats
Strandings and entanglement in fishing nets/gill nets pose problems for this species, but the chief threat is hunting. For several hundred years, long-finned pilot whales have been hunted off the coasts of the Faroe Islands, (Danish islands in the northeast Atlantic). Whole pods are rounded up by boats and driven towards the coastline where they are dragged ashore and killed. In the last decade, an average of 1,200 individual pilot whales have been killed each year in this way. The Faeroese people defend this hunt fiercely, and maintain that it is long-standing tradition and a source of protein.
This species is primarily hunted for blubber, head, and jaw oil. The principal present fishery for Long-finned pilot whales lies in the Faroe Islands and Greenland. Although this fishery has been pursued since the 9th century AD, catch levels have apparently not caused almost complete stock decimation, such as occurred off Newfoundland. Catch statistics exist from the Faroes since 1584, unbroken from 1709 to today, showing an annual average catch of 850 pilot whales (annual take varying from none to 4480) with a cyclic variation according to the North-Atlantic climatic variations. The International Whaling Commission, ICES and North Atlantic Marine Mammal Commission note an estimated subpopulation size of 778,000 (CV=0.295) in the eastern North Atlantic and approximately 100 000 around the Faroes.
A particular threat to the species is hunters who exploit the social behavioural instinct of the species to herd; this phenomenon has been exploited in Newfoundland in the decimation of that population, as well as the Faroes and other sites. Other catches are reported from Newfoundland, the Mediterranean and the Atlantic coast of France. Very few are reported taken incidentally in fisheries in the Southern Hemisphere; however, according to Bernard and Reilly, there are probably more pilot whales taken incidentally than presently documented. On the east coast of the USA, the foreign Atlantic mackerel fishery was responsible for the take of 141 pilot whales as bycatch in 1988. This fishery was suspended in early May of that year as a direct result of this anomalously high take.
A 1990 workshop to review mortality of cetaceans in passive nets and traps documented an annual kill of 50 to 100 G. melas off the Atlantic coast of France. Long-finned pilot whales are also known to be taken incidentally in trawl and gillnet fisheries in the western North Atlantic, and in swordfish driftnets in the Mediterranean This species, like beaked whales, is likely to be vulnerable toloud anthropogenic sounds, such as those generated by ship sonar, including seismic exploration. Also, predicted impacts of global climate change on the marine environment may affect long-finned pilot whales, and may induce changes in the species’ range, abundance and/or migration patterns. In addition, this species is thought to be a systematic prey to the Orca and some shark taxa.
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Portions of this article were researched and written by a student at Texas Tech University participating in the Encyclopedia of Earth's (EoE) Student Science Communication Project. The project encourages students in undergraduate and graduate programs to write about timely scientific issues under close faculty guidance. All articles have been reviewed by internal EoE editors, and by independent experts on each topic.
