Tursiops truncatus (Atlantic bottlenose dolphins) (Pine Island Sound, Florida, USA) 6 : 無料・フリー素材/写真
Tursiops truncatus (Atlantic bottlenose dolphins) (Pine Island Sound, Florida, USA) 6 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
|---|---|
| 説明 | Tursiops truncatus (Montagu, 1821) - Atlantic bottlenose dolphins in Florida, USA. (December 2008)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.Shown above is a small pod of Atlantic bottlenose dolphins in Pine Island Sound, Florida. Dolphins are cetaceans - medium-sized to very large aquatic mammals that descended from terrestrial ancestors during the early Cenozoic. Cetaceans are the whales, dolphins, and porpoises. Most cetaceans are marine, but some freshwater forms also exist - the river dolphins. As a group, cetaceans are characterized by having streamlined, somewhat cigar-shaped bodies; a thick blubber layer; front limbs that are flippers; non-functional hind limbs; an elongated skull; 1 or 2 blowholes atop the head; almost no body hair; a horizontally-oriented tail that provides propulsion; and a soft outer skin layer, which improves water flow around the body.Classification: Animalia, Chordata, Vertebrata, Mammalia, Cetacea, DelphinidaeLocality: Pine Island Sound, offshore from the Fort Myers urban area, Gulf of Mexico coast of southern Florida, USA----------------More info. at:en.wikipedia.org/wiki/Cetaceaanden.wikipedia.org/wiki/Common_bottlenose_dolphin |
| 撮影日 | 2008-12-18 14:00:37 |
| 撮影者 | James St. John |
| タグ | |
| 撮影地 |