Why are Dolphins Considered Mammals?
Dolphins live in the ocean. They look like giant fish with tails, fins and no legs, but they are not fish at all. They are mammals, like cows, monkeys, elephants and people.
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Identification
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Mammals are named for "mamma," the Latin word for breasts, because all female mammals produce breast milk and nurse their young, which are born live. Mammals also have hair, backbones and sweat glands. They are warm-blooded creatures with a complex heart that usually has four chambers and allows for blood to circulate throughout the body, carrying the oxygen that they breathe in. Mammals also have no more than four limbs and all mammals have two front limbs.
Features
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Dolphins are in the delphinidae family and the cetacean order. They have two flippers, which constitute the two front limbs that all mammals possess. They do not have a second pair of limbs but they do have flukes at their tail and a dorsal fin. The flukes are like paddles and the dorsal fin is like a rudder that keeps the dolphin balanced.
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Function
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Dolphins are warm-blooded animals, a characteristic of mammals. Like other mammals, dolphins have lungs, so they come to the surface every minute to breathe air through a nostril, called a blow hole. Newborn baby dolphin calves must breathe much more often.
Considerations
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It takes 11 ro 12 months for a dolphin to fully develop in its mother's womb. Then, after a labor that lasts about 35 minutes, the calf is born. Right away, the mother has to get the calf to the surface so it can breathe. The calf nurses at the mother's nipple, like every other mammal, but it does not suck. The milk streams into the calf's mouth. Every few seconds, the nursing dolphin calf has to surface to breathe.
Expert Insight
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Dolphins have been known to live for 25 years. Pilot whales, which are dolphins, can live twice as long. Some researchers believe that dolphins are one of the most intelligent creatures on earth. They can be trained to dive, do tricks, and communicate with people. In fact, trained dolphins are even used by the United States military for specialized missions.
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