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Transcript of Dolpins
In the wild, these sleek swimmers can reach speeds of over 18 miles (30 kilometers) an hour. They surface often to breathe, doing so two or three times a minute. Bottlenose dolphins travel in social groups and communicate with each other by a complex system of squeaks and whistles. Schools have been known to come to the aid of an injured dolphin and help it to the surface.
Bottlenose dolphins track their prey through the expert use of echolocation. They can make up to 1,000 clicking noises per second. These sounds travel underwater until they encounter objects, then bounce back to their dolphin senders, revealing the location, size, and shape of their target.
When dolphins are feeding, that target is often a bottom-dwelling fish, though they also eat shrimp and squid. These clever animals are also sometimes spotted following fishing boats in hopes of dining on leftovers.
Bottlenose dolphins are found in tropical oceans and other warm waters around the globe. They were once widely hunted for meat and oil (used for lamps and cooking), but today only limited dolphin fishing occurs. However, dolphins are threatened by commercial fishing for other species, like tuna, and can become mortally entangled in nets and other fishing equipment. Bottlenose Dolphin Life Bottlenose Dolphin Anatomy Bottlenose dolphins are found in tropical oceans and other warm waters around the globe.
They were once widely hunted for meat and oil (used for lamps and cooking), but today only limited dolphin fishing occurs. However, dolphins are threatened by commercial fishing for other species, like tuna, and can become mortally entangled in nets and other fishing equipment.
The modern fishing fleet harvests the seas indiscriminately. It does not distinguish between fish and marine mammals, and in its quest for increased efficiency, slaughters thousands of dolphins each year drowned in nets. As the world's fish stocks become more depleted from over-fishing, there is a danger that man's pursuit of protein food will lead to a more determined capture of dolphins and whales to satisfy the demand.
Several fishing practices have taken a toll on dolphin populations. Most lethal are drift nets and nets called purse seines, used to fish yellow fin tuna. Because tuna often swim beneath dolphin schools, dolphins are actively sought. Fishermen then circle the tuna with mile-long (1.6-km) seine nets that trap fish and mammals alike. When this practice started in the 1950s, it killed more than a quarter of a million dolphins a year. Now boat captains are trained to do maneuvers that help release the dolphins. The dolphin kill now totals around 20,000 a year.
The drift net, though, is the most indiscriminate killing device yet used at sea. Up to 40 miles (64 km) long, drift nets hang draped from floats, trapping virtually everything in their path. Fishermen haul the nets aboard, store the fish or squid, and discard everything else, including dolphins that have drowned while trapped. About the Program The program has been dogged by controversy over the treatment of the animals and speculation as to the nature of its mission and training. This has been due at least in part to the secrecy of the program, which was de-classified in the early 1990s. Since the program’s inception, there have been ongoing animal welfare concerns, with many opposing the use of marine mammals in military applications, even in essentially non-combatant roles such as mine detecting.It has been reported that the program will come to a close beginning in 2017. History of the Program The program started in 1962. The purpose was to study the dolphins' senses and capabilities, such as their natural sonar and deep-diving physiology. How dolphins can be used to perform useful tasks, such as searching for and marking objects in the water, was studied. They discovered that trained dolphins and sea lions could be worked untethered in the open sea. In 1965, a Navy dolphin named Tuffy participated in the SEALAB II project carrying tools and messages between the surface and the home 200 feet below. Tuffy was also trained to locate and guide lost divers to safety. Tuffy Echolocation- the general method of locating objects by determining the time for an echo to return and the direction from which it returns, as by radar or sonar. More information at http://dictionary.reference.com/browse/echolocation?s=t By: Maggie Gubbins Sources can be found at:
1. "Bottlenose Dolphin Facts and Information", www.dolphins-world, Bioexpedition.com, 2012, Web, 1/17/13, http://www.dolphins-world.com/Bottlenose_Dolphin_Facts_and_Information.html
2. "Bottlenose Dolphins", www.marinbio.org, Marin Bio Copyright, 2013, Web, http://marinebio.org/species.asp?id=33
3. "Bottlenose Dolphin", www.nationalgeographic.com, National Geographic Society, 2013, Web, 1/24/13, http://animals.nationalgeographic.com/animals/mammals/bottlenose-dolphin/#
4. "Dolphins in Danger", www.idw.org, NP, ND, Web, 1/31/13, http://www.idw.org/html/dolphins_in_danger.html
5. "United States Navy Marine Mammal Program", www.wikipedia.org, Wikimedia Foundation Inc., 1/9/13, Web, 2/7/13, http://en.wikipedia.org/wiki/United_States_Navy_Marine_Mammal_Program Works Cited http://animals.nationalgeographic.com/animals/mammals/bottlenose-dolphin/# http://www.tmmsn.org/education/dolphin_anatomy/anatomy3.gif The End