Thursday, May 9, 2013

The Killer whale and the Humpback

Galina sent me this nice FDC with the setenant pair of stamps showing two of the greatest type of whales. The Killer whale and the Humpback. These stamps and the cover were issued by Russia on 8.2.2012.
Killer whales (Orcinus orca).  Killer whales are the largest dolphins in the world. Males can grow up to 10 meters in length; females are smaller — up to just 8 meters in length. The sex of mature orcas can be discerned by the size and shape of the dorsal fin: the male has an elongated dorsal fin, up to 2 meters high. Females and subadult animals of both sexes have smaller sickle-shaped dorsal fins.
One key species feature of killer whales is their coloration. The back and sides of the large body are black; the lower jaw, throat and belly are white. On the rear part of the body, the white color goes up the sides, sometimes culminating at the back. Two white patches are located before the eyes and above them. Behind the dorsal fin there is an asymmetrical saddle patch, which is used for the photo-identification of individual whales. In Arctic and Antarctic waters, this white color can be masked by algae covering the orca´s skin and these patches appear fawn or brown. Killer whales have 10-14 teeth on the each half of the upper jaw and 8-14 on the lower. When the mouth closes, the teeth of the upper jaw fit into the spaces between the teeth of lower jaw, helping to catch and bite prey.
The Humpback whale (Megaptera novaeangliae) is a species of baleen whale. One of the larger rorqual species, adults range in length from 12–16 metres (39–52 ft) and weigh approximately 36,000 kilograms (79,000 lb). The humpback has a distinctive body shape, with unusually long pectoral fins and a knobbly head. An acrobatic animal known for breaching and slapping the water with its tail and pectorals, it is popular with whale watchers off Australia, New Zealand, South America, Canada, and the United States.
Males produce a complex song lasting 10 to 20 minutes, which they repeat for hours at a time. Its purpose is not clear, though it may have a role in mating.
Found in oceans and seas around the world, humpback whales typically migrate up to 25,000 kilometres (16,000 mi) each year. Humpbacks feed only in summer, in polar waters, and migrate to tropical or subtropical waters to breed and give birth in the winter. During the winter, humpbacks fast and live off their fat reserves. Their diet consists mostly of krill and small fish. Humpbacks have a diverse repertoire of feeding methods, including the bubble net feeding technique.
Like other large whales, the humpback was and is a target for the whaling industry. Once hunted to the brink of extinction, its population fell by an estimated 90% before a moratorium was introduced in 1966. While stocks have since partially recovered, entanglement in fishing gear, collisions with ships, and noise pollution continue to impact the 80,000 humpbacks worldwide.

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