Cetaceans
Cetaceans, the 83 species of whales, dolphins, porpoises, may be the most specialized of all mammals. They have evolved for life in the water, with a torpedo shaped hairless body, flipper-like forelimbs and the reduction of hindlimbs. Cetaceans are mammals and must breathe air ; the nostrils have moved to the top of the head and developed muscular valves. The order contains some of the most social and highly intelligent species known to man.
The order is usual divided into two suborders: the toothed whales and the baleen whales. There are 14 species of baleen whales divided among four families. They posses baleen plates instead of teeth. These plates filter prey which consists of small crusteceans or plankton depending on the species. The lagest animal on Earth , the Blue Whale is a baleen whale. The suborder of toothed whales is much larger containing 9 families and 71 species. Most toothed whales communicate and navigate by echo-lication. All species have a fluid filled swelling called a melon anterior to the forehead which is used in this process.
The order is usual divided into two suborders: the toothed whales and the baleen whales. There are 14 species of baleen whales divided among four families. They posses baleen plates instead of teeth. These plates filter prey which consists of small crusteceans or plankton depending on the species. The lagest animal on Earth , the Blue Whale is a baleen whale. The suborder of toothed whales is much larger containing 9 families and 71 species. Most toothed whales communicate and navigate by echo-lication. All species have a fluid filled swelling called a melon anterior to the forehead which is used in this process.
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