Dolphins :: essays research papers

Dolphins   Ã‚  Ã‚  Ã‚  Ã‚  Dolphins are mammals closely related to whales and porpoises. Dolphins have a powerful and streamlined body. They are found in all seas and oceans. Dolphins can be told apart from porpoises by their nose, which is beaklike, and also their conical teeth. Porpoises have a flatter nose, sharper teeth, and a more solid body.   Ã‚  Ã‚  Ã‚  Ã‚  There are 32 known species of dolphins. The bottle-nosed dolphin is often the species used in aquatic shows. The common dolphin inspired many Mediterranean folk lores. Both of the dolphins above appear in open waters, usually around cruise ships. They like to show off around the boat.   Ã‚  Ã‚  Ã‚  Ã‚  There are also freshwater dolphins that live in rivers of Asia and South America. The Buffeo dolphin has been spotted up to 1250 miles up he Amazon River. The buffeo is the smallest of all dolphins averaging about 4 feet. The bottlenose is closer to 10 feet. The killer whale, which is also considered a dolphin, can grow to be 30 feet long. The pilot whale is also considered a dolphin.   Ã‚  Ã‚  Ã‚  Ã‚  Dolphins were once hunted by commercial boats for the small amount of oil that can be extracted from their body. This oil is used to lubricate small parts in watches. Cheaper oils have been found, so dolphins are not hunted for this reason anymore. Dolphins can be caught in tuna nets by accident. Since dolphins have to breath at the surface they drown in tuna nets. It is estimated that 4.8 million dolphins were killed in tuna nets from 1959 to 1972. Under pressure from animal rights activists tuna consumers will not accept tuna from canners that do not protect dolphins. Animal rights activists also believe that dolphins shouldn't be in captivity for use in aquatic shows.   Ã‚  Ã‚  Ã‚  Ã‚  Dolphins eat a lot of food in a day, usually about one third of their body weight. A dolphin's diet consists of mostly fish and squid. Dolphins can swim very fast, so they are able to easily catch their food. The dolphin has 200 to 250 sharp teeth. Dolphins follow schools of fish in groups. The Pacific white-sided species is estimated to travel in groups with tens of thousands of members, while on the other hand bottlenose dolphins travel in groups that contain only a few members.   Ã‚  Ã‚  Ã‚  Ã‚  Dolphin, like whales, breathe through a blowhole in the top of their head. While traveling dolphins break the surface once every two minutes. When dolphins exhale water is sometimes thrown from the blowhole. After exhaling the dolphins inhale and disappear into the ocean. A dolphins lungs are adapted to resist the physical problems that are caused by quick changes in pressure.