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Young World
WORLD OF SCIENCE
It’s a whale!
DR. T.V. PADMA
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Did you know that the whale was closely related to the hippopotamus?
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Photo: AP
Mammal : At sea.
So what are whales and dugongs? They are marine mammals, not fish. We use the term “whale” quite incorrectly. For instance, killer whales and pilot whales aren’t whales in the biological sense — they are actually other types of marine mammal. Killer whales are dolphins, according to their biol
ogical classification. Biologically speaking, only some families within the order cetacea are considered whales.
In the past
The whale is closely related to the hippopotamus. Ancestors of whales were toed mammals that went from their terrestrial (land) habitats into the water. They still retain most mammalian characteristics: whales give birth to live young, which they feed from mammary glands, they breathe air through their lungs, and they are warm-blooded. Beneath the skin, whales have a layer of fat called blubber which insulates in cold waters. Because they breathe air through lungs, they hold their breath when they dive.
Some whales, called baleen whales, have a sieve-like structure in their jaws. This helps them filter through the water, and catch tiny plankton on which they feed. The largest species of whales are baleen whales — the blue whale is the largest animal that we know. It can reach 35m in length and weight 150 tonnes.
Some species of whales have teeth. They usually communicate using clicks and grunts that can be heard for miles in the ocean. The toothed whale category includes dolphins and porpoises.
As a group, cetaceans are noted for their high intelligence. There are about 90 species of cetaceans that we know of today.
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