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The Dolphin Family

There are some 80 species of whales, dolphins and porpoises (collectively known as cetacean) all over the world. Scientists usually categorize them into two large groups base on the way they feed: baleen whales (also called Mysticeti) and toothed whales (also called Odontoceti). Baleen whales feed on krill and small fish, which are basically near to the bottom of the marine food chain. Toothed whales feed on larger fish up the marine food chain.

The number of blowhole for baleen whales and toothed whales are different. Baleen whales have two blowholes while toothed whales have one blowhole.

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Toothed whale – dolphin has only one blowhole Teeth of toothed whales
(Left: tooth of sperm whale; Right: tooth of Longman’s beaked whale)
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Baleen whale – humpback whale has two blowholes One of the baleens of a blue whale

What is a porpoise? How does it differ from a dolphin?
Porpoise is a cetacean. It is usually smaller and it does not have a long beak as the dolphins. The shape of their teeth is also different: porpoise's teeth are like a spade, while dolphin's teeth are like a cone. In general, porpoises are shy animals and they seldom jump out of water.