Thursday, March 14, 2013

Pilot Whale

Pilot whale are Cetacea belonging to the  Globicephala genus . There are two extant species, the long-finned pilot whale (G. melas) and short-finned pilot whale (G. macrorhynchus). The two are not readily distinguished at sea and analysis of the skull is the best way to distinguish between them. Between the two species, pilot whales range in waters nearly worldwide with long-finned pilot whales that live in the cold waters and short-finned pilot whales that live in tropical and subtropical waters. Pilot whale is one of the largest of the sea dolphins, exceeded only by the size of killer whales. They and other large members of the dolphin family are also known as blackfish.

Pilot whales, especially squid eaters, but will feed on fish as well. They are also very social and studies have shown that men and women still in their mother's ghost, an unusual trait among mammals, is also found in certain killer whale communities. Short-finned pilot whales are also one of the few mammalian species in which women experience menopause and post-reproductive females may contribute to the survival of the younger members of their pod. Pilot whales stranded themselves known for the beach, and is one of the most common stranders Cetacea. Several theories have been put forward to explain this behavior. Status of the two species is not understood and they were subject to direct and indirect catches by the fishing industry. Whalers in some countries continue to hunt pilot whales.

Most pilot whales dark gray, brown or black, but has a few light areas such as field gray saddle behind the dorsal fin. Other bright areas are anchor-shaped patch under the chin, kobaran faint marking behind the eyes, a big sign on the stomach and genital patch. Dorsal fin is set forward on the back and sweeps backwards. A pilot whale is stronger than most of the dolphins and have a special large, round melons. Pilot whales have long, sickle-shaped fins and tail stock is flattened from side to side. Long-finned pilot whales men have grown more rounded melon than girls, although this does not seem to be the case for short-finned pilot whales off the Pacific coast of Japan.

Pilot whales and short-finned length very similar making it difficult to tell the two species apart. They are traditionally distinguished by the pectoral fin length relative to total body length and number of teeth. The long-finned pilot whale is thought to have 9-12 teeth in each row and flippers 1/5 of the total body length, compared to the short finned pilot whale with his 7-9 teeth in each row and flippers 1/6 of the total length body. Study whales in the Atlantic show a lot of overlap in the characteristics of a species, not make them Clines special features. Thus, biologists have since used the skull differences to distinguish the two species. Finned pilot whale skull from short has rostum shorter and wider with premaxilla, which includes more than the upper jaw. In contrast, long-finned pilot skull whale has rostum longer if need be explained and maxille more open.

Size and weight depending on species for finned pilot whales are generally larger than short-finned pilot whales. Their survival rate is around 45 years in men and 60 years in females for both species. Both species show sexual dimorfisme. Long-finned pilot whales Adult body length reaching about 6.5 m, with a male to 1 m longer than females. Their body mass reached to 1,300 kg in women and up to 2,300 kg in males. For short-finned pilot whales, adult females reach about 5.5 m long body, while men reach 7.2 m and may weigh up to 3,200 kg.

Pilot whales can be found in the ocean almost all over the world. The long-finned pilot whales prefer the water a little cooler than short finned and is divided into two populations. Smaller clusters found in an encircling band in the Southern Ocean running from approximately 20 ° to 65 ° S S. This can be seen off the coast of Chile, Argentina, South Africa, Australia and New Zealand. There are estimated to be more than 200,000 people in this population. The second population is much larger and inhabit the North Atlantic Ocean, in a band stretching from South Carolina in the United States across to the Azores and Morocco at the southern end and from Newfoundland to Greenland, Iceland and northern Norway in the north. This population is estimated to be 778,000 people. It is also present in the western part of the Mediterranean Sea.

The short-finned pilot whales less densely populated areas. It is found in temperate and tropical waters of the Indian Ocean, the Atlantic and the Pacific. Its population overlaps slightly with long finned pilot whales off the coast of temperate North Atlantic and the Southern Ocean. There are 150,000 people 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. Pilot whales are generally nomadic, but some permanent residents throughout the year in places such as Hawaii and parts of California. They prefer waters of the shelf break and the water is dirty.

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