water at 1.5 km/sec which is four times faster than sound traveling through air. Sound waves bounce off objects and return in the form of an echo. The sound is received and counducted through the lower jaw to middle ear, inner ear and then hearing in the center of the brain. Brain receives sound waves in the from of nerve impulses and relay messages of sound. This enables the dolphin to interpret the sounds meaning. This system is known as the echolocation system which is the ability that dolphins possess to see with their ears by listening for echoes. They can determine size, shape, speed, distance and direction. A dolphins average life span is 25 to 65 years. A dolphin dies for many reasons. One is the variety of diseases and parasites that a dolphin can transmit. Some of these are tapeworm, roundworm, and viral and bacterial infections. Morbillivirus is also a huge killer of the dolphin. Sharks also eat dolphins. Rare, but occasionally killer whales eat dolphins as well.Humans have a huge impact on the death of dolphins. They are taken in for food, leather, oil and fertilizer uses. The river dolphins are the majority of dolphins becoming extinct. The River dolphins frequent the rivers in Asia and South America. These dolphins are affected from our pollution and habitat destruction. Fisherman also catch dolphins in their nets. The tuna industry has killed as many as 6 to 12 million dolphins in the eastern Pacific in the last 30 years. Dolphins have been studied for quite some time to discover there intelligence level. One test done by Pieter Arend Folkens was to teach the dolphin to pick up trash in his cage. If he brought the trainer a piece of trash, he would get a fish. Every day the dolphin would be able to find trash in his tank. The trainers went down below the tank, only to discover that the dolphin was stashing trash in the corner of the tank. The dolphin would also only bring up a ripped off pie...
