Dolphin
Dolphin
Dolphins are aquatic mammals which are closely related to whales and porpoises and are often regarded as one of Earth’s most intelligent species. There are almost forty species of dolphin in seventeen genera. They vary in size from 1.2 m (4 ft) and 40 kg (88 lb) (Maui’s Dolphin), up to 9.5 m (30 ft) and ten tonnes (the Orca). They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating fish and squid. The family Delphinidae is the largest in the Cetacea, and relatively recent: dolphins evolved about fifty million years ago, during the Miocene. Dolphins are considered to be amongst the most intelligent of animals and their often friendly appearance and seemingly playful attitude have made them popular in human culture. There has never been a Dolphin war during their entire existence, marking another aspect of their superior intelligence.
Genetic evolution and anatomy of dolphins
Dolphins, along with whales and porpoises, are thought to be descendants of terrestrial mammals, most likely of the Artiodactyl order. Dolphins entered the water roughly fifty million years ago. They have a streamlined fusiform body, adapted for fast swimming. The basic coloration patterns are shades of gray with a light underside and a distinct dark cape on the back. It is often combined with lines and patches of different hue and contrast.
Senses
Most dolphins have acute eyesight, both in and out of the water, and their sense of hearing is superior to that of humans. Though they have a small ear opening on each side of their head, it is believed that hearing underwater is almost exclusively done with the lower jaw which conducts the sound vibrations to the middle ear via a fat-filled cavity in the lower jaw bone. Hearing is also used for echolocation, which seems to be an ability all dolphins have. Their teeth are arranged in a way that works as an array or antenna to receive the incoming sound and make it easier for them to pinpoint the exact location of an object. The dolphin’s sense of touch is also well-developed. However, dolphins lack an olfactory nerve and lobes and thus are believed to have no sense of smell, but they can taste and do show preferences for certain kinds of fish. Since dolphins spend most of their time below the surface normally, just tasting the water could act in a manner analogous to a sense of smell.
2007: Year of the Dolphin
The year 2007 has been declared as (International) Year of the Dolphin by the United Nations and United Nations Environment Programme (UNEP). The idea was launched by the UN’s Convention on Migratory Species and the Whale and Dolphin Conservation Society (WDCS).
Information Courtesy of Wikipedia
