Short-finned pilot whale
|Short-finned pilot whale |
|Short-finned pilot whale surfacing|
|Size compared to an average human|
The short-finned pilot whale (Globicephala macrorhynchus) is one of the two species of cetaceans in the genus Globicephala. It is part of the oceanic dolphin family (Delphinidae), though its behaviour is closer to that of the larger whales.
Short-finned pilot whales can be confused with their relatives the long-finned pilot whales, but there are various differences. As their names indicate, their flippers are shorter than those of the long-finned pilot whale, with a gentler curve on the edge. They have fewer teeth than the long-finned pilot whale, with 14 to 18 on each jaw. Short-finned pilot whales are black or dark grey with a grey or white cape. They have grey or almost white patches on their bellies and throats and a grey or white stripe which goes diagonally upwards from behind each eye.
Adult males may have a number of scars on their bodies. Their heads are bulbous and this can become more defined in older males. Their dorsal fins vary in shape depending on how old the whale is and whether it is male or female. They have flukes with sharply pointed tips, a distinct notch in the middle and concave edges. They tend to be quite slender when they are young, becoming more stocky as they get older.
The short-finned whale has a stocky body, a bulbous forehead, no prominent beak, long flippers sharply pointed at the tip, black or dark grey color, and the dorsal fin set forward on body. The flukes are raised before a deep dive; they may float motionless at the surface, frequently are seen in very large groups, prefer deep water, and may be approached. Their diets are composed of fish, squid, and octopus.
Adults males are about 5.5 meters (18 ft) in length, whereas adult females only reach about 3.7 meters (12 ft) in length. Adults can weigh from 1,000 to 3,000 kg (2200-6600 lbs) (1,000-3,000 kg). When they are born, short-finned pilot whales are about 1.4–1.9 m (4 ft 7 in–6 ft 3 in) long and weigh about 60 kg (130 lb). Males live nearly 45 years, whereas females can live up to 60 years and go through menopause.
Short-finned pilot whales are very sociable and are rarely seen alone. They are found in groups of 10 to 30, though some pods are as large as 50. In a few sitings of pods, over several hundred animals have also been recorded. Pods are primarily matrilineal, or a female-based society. Some older females have been recorded actually taking care of calves that are not their own. Males are polygynous, meaning they will mate with multiple females at one time or throughout their lives. Pods are often found with around one mature male per every eight mature females. Maturing males will often leave their birth school, but most females will stay in the same pod their entire lives. They are sometimes seen logging and will allow boats to get quite close. They rarely breach, but may be seen lobtailing (slapping their flukes on the water surface) and spy-hopping (poking their heads above the surface). Before diving, they arch their tails and raise them above the surface. When coming to the surface to breathe, adults tend to show only the tops of their heads, whereas calves will throw their entire heads out of the water. Adults occasionally porpoise (lift most of the body out of the water) when swimming particularly quickly.
Females mature at about 10 years of age and will start having calves every five to eight years. A female may nurse a calf for up to 15 years as long as it is the last born calf. Their gestation period lasts just over a year, and a female will have from four to six calves in her lifetime. A calf will suckle from its mother for a minimum of two years, but most will for nearly five years. A female will usually stop reproducing once reaching the age of about 40 years.
The short-finned pilot whale primarily feeds on squid, but will also feed on certain species of fish and octopus. They feed at 300 m (980 ft) or more, and spend great lengths of time at depth. A pod may spread out up to 800 m (870 yd) to find food. They have also been reported to "harass" sperm whales and dolphins, so marine mammals could also potentially be part of their diets.
They are known as the 'cheetahs of the deep' for the high-speed pursuits of squid at depths of hundreds of metres.
Short-finned pilot whales, unlike the related long-finned pilot whale, are found in most waters around the world. They primarily inhabit warm tropical waters, but usually stay offshore in the deeper waters. They also tend to be found in areas with a high density of squid. Known populations are found in the North Atlantic stretching all the way south to northern South America, including the Gulf of Mexico and to Africa, as well. They are thought to migrate south into the western North Atlantic in the late winter/early spring. Other populations are recorded throughout the entire Pacific stretching from Japan to southern Guatemala, as well as the Red Sea and Indian Ocean.
The two distinct populations off the coasts of Japan have differences in their anatomy and genetics, and could potentially comprise more than one distinct species or subspecies. Their exact taxonomy has yet to be verified.
Once commonly seen off of Southern California, short-finned pilot whales disappeared from the area after a strong El Niño year in the early 1980s, according to the National Oceanic and Atmospheric Administration. In October 2014, crew and passengers on several boats spotted a pod of 50-200 off Dana Point, California.
The short-finned pilot whale is covered by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS) and the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS). The species is further included in the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia (Western African Aquatic Mammals MoU) and the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU)
In a very few areas of Japan, mainly along the central Pacific coast, pilot whales are commercially hunted and the meat is available for human consumption. In certain restaurants or izakayas, pilot whale steaks are marinated, cut into small chunks, and grilled. The meat is high in protein and low in fat (a whale's fat is contained in the layer of blubber beneath the skin). When grilled, the meat is slightly flaky and quite flavorful, somewhat gamey, though similar to a quality cut of beef, but with distinct yet subtle undertones recalling its marine origin.
- Mead, J.G.; Brownell, R. L. Jr. (2005). "Order Cetacea". In Wilson, D.E.; Reeder, D.M. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 723–743. ISBN 978-0-8018-8221-0. OCLC 62265494.
- Taylor, B.L.; Baird, R.; Barlow, J.; Dawson, S.M.; Ford, J.; Mead, J.G.; Notarbartolo di Sciara, G.; Wade, P. & Pitman, R.L. (2011). "Globicephala macrorhynchus". The IUCN Red List of Threatened Species. IUCN. 2011: e.T9249A12972356. doi:10.2305/IUCN.UK.2011-2.RLTS.T9249A12972356.en. Retrieved 25 December 2017.
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- Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas
- Official website of the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area
- Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia
- Official webpage of the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region
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