Balaenoptera physalus (finback whale) (North Atlantic Ocean) 2 : 無料・フリー素材/写真
Balaenoptera physalus (finback whale) (North Atlantic Ocean) 2 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Balaenoptera physalus (Linnaeus, 1758) - finback whale skeleton (real) from the North Atlantic Ocean. (public display, Denver Museum of Nature & Science, Denver, Colorado, USA)Mammals are the dominant group of terrestrial vertebrates on Earth today. The group is defined based on a combination of features: endothermic (= warm-blooded), air-breathing, body hair, mother's milk, four-chambered heart, large brain-to-body mass ratio, two teeth generations, differentiated dentition, and a single lower jawbone. Almost all modern mammals have live birth - exceptions are the duck-billed platypus and the echidna, both of which lay eggs.Mammals first appear in the Triassic fossil record - they evolved from the therapsids (mammal-like reptiles). Mammals were mostly small and a minor component of terrestrial ecosystems during the Mesozoic. After the Cretaceous-Tertiary mass extinction at 65 million years ago, the mammals underwent a significant adaptive radiation - most modern mammal groups first appeared during this radiation in the early Cenozoic (Paleocene and Eocene).Three groups of mammals exist in the Holocene - placentals, marsupials, and monotremes. Other groups, now extinct, were present during the Mesozoic.Whales are members of Order Cetacea, which includes the dolphins and porpoises. Cetaceans have intermediate- to very large-sized bodies that are streamlined (cigar-shaped) and have a thick blubber layer for heat insulation purposes. They are evolutionarily derived from terrestrial mammals that had four legs. The former front legs are now flippers. The hind legs are highly reduced and non-functional in whales. The skull is elongated, with one or two blowholes atop the head. The tail is horizontally-oriented, unlike the vertically-oriented caudal fin ("tail") of a fish. Vertical movement of a whale's tail provides propulsion. Whale bodies have a soft outer skin layer with almost no hair - this improves water flow around the body.Whales are famous for being deep and long divers. Sperm whales can dive to over 9,200 feet deep. Northern bottlenose whales can hold their breath for over two hours. Unlike humans, whales have evolved mechanisms for coping with diving diseases such as nitrogen narcosis and decompression sickness.Cetaceans are subdivided into two groups - the odontocete whales and the mysticete whales. The odontocetes are the toothed whales and include the sperm whale, killer whale, dolphins, and porpoises. Mysticete whales are the baleen whales - they include the blue whale, finback whale, humpback whale, gray whale, right whale, minke whale, sei whale, etc. Baleen whales have much larger bodies than toothed whales and have two blowholes atop the head. They eat low on the food pyramid - their dominant food is krill, which is an abundant, small crustacean (Animalia, Arthropoda, Crustacea). Baleen whales usually feed near the surface. Instead of having teeth, these animals have baleen - parallel rows of keratin plates hanging down from the upper jaw. Baleen is used to concentrate small prey and separate them from seawater. Individual baleen plates can be up to 14 feet long.The finback whale is the 2nd-largest animal on Earth - it is a baleen whale.Finback whale skeletons are rarely on display. The example shown above is in Denver's natural history museum in Colorado.From museum signage:"Fin whales are the second-largest living animal, after blue whales.The skeleton weighs 2,285 pounds (1,271 kilograms).With its flesh it may have weighed 54,000 pounds!Actually, this one's just about average size - 56 feet (17 meters) long. They can reach 88 feet (26.8 meters).It's a male, from the North Atlantic - we did DNA tests.Fast - up to 23 miles per hour (37 kilometers per hour). They're nicknamed "Greyhound of the Sea".No, they don't have teeth. Fins are baleen whales - they filter tiny food called krill out of the water with great brush-like rows of baleen. An adult can east about 4,000 pounds (1,800 kilograms) in a day.At birth, they're about 20 feet long and weigh two tons. That's a whale of a baby!Fin whales are endangered. When whaling ships began to use steam power, fin whales were on the prime hunting list. Now they're on the International Union for Conservation of Nature and Natural Resources red list and the United States Endangered Species Act list.How did a whale get to Colorado?Cripple Creek mining mogul W.S. Stratton purchased this fin whale skeleton in 1900, in Coronado Beach, California. He loaded the bones into six boxcars and shipped them to the new Colorado College Natural History Museum. The skeleton stayed there until the museum closed in 1977.Donated by Colorado College, Colorado Springs, 1977."Classification: Animalia, Chordata, Vertebrata, Mammalia, Artiodactyla, Cetacea, Mysticeti, Balaenopteridae-------------------See info. at:en.wikipedia.org/wiki/Fin_whaleanden.wikipedia.org/wiki/Baleen_whaleanden.wikipedia.org/wiki/Cetacea |
| 撮影日 | 2013-10-26 14:58:04 |
| 撮影者 | James St. John |
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