Dolphins

The name is from Ancient Greek δελφίς delphis meaning "with a womb" which can be interpreted as meaning "a 'fish' with a womb".

Dolphins are aquatic mammals which are closely related to whales and porpoises. There are almost forty species of dolphin in seventeen genera. They vary in size from 1.2 metres (4 ft) and 40 kilograms (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 ten 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.

The Ganges River Dolphin (Platanista gangetica gangetica) and Indus River Dolphin (Platanista gangetica minor) are two sub-species of freshwater or river dolphins found in Bangladesh, India and Pakistan. From the 1970s they had commonly been regarded as separate species. The Ganges River Dolphin is primarily found in River Ganges and its tributaries in India while the Indus River Dolphin is found in the Indus river in Pakistan. However in 1998, a seminal work on cetacean taxonomy listed them as a single species once again (see taxonomy below). The single species is likely to have either the Ganges and Indus River Dolphin or Indian River Dolphin as its common name, although neither has yet spread into wide usage.

The Baiji (Traditional Chinese: 白鱀豚; pinyin: báijìtún) (Lipotes vexillifer, Lipotes meaning "left behind", vexillifer "flag bearer") was a freshwater dolphin found only in the Yangtze River in China. Nicknamed "Goddess of the Yangtze" (長江女神) in China, the dolphin was also called Chinese River Dolphin, Yangtze River Dolphin, Beiji, Pai-chi (Wade-Giles), Whitefin Dolphin and Yangtze Dolphin. It is not to be confused with the Chinese White Dolphin (中華白海豚).

The Baiji population declined drastically in recent decades as China industrialized and made heavy use of the river for fishing, transportation, and hydroelectricity. Efforts were made to conserve the species, but a late 2006 expedition failed to find any Baiji in the river. Organizers declared the Baiji "functionally extinct",^[1] which arguably makes it the first aquatic mammal species to become extinct since the 1950s.