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Bottlenose dolphin

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The Bottlenose Dolphin is one of the most threatened cetacean species in Europe, and consequently has extensive legislative protection at a European level.

Contents

[edit] Why is it a threatened species?

The bottlenose dolphin is hunted for oil and meat. use its oil for attracting catfish in a unique method of angling

It also gets caught in gillnets - huge nets that are thrown in the waters to catch a large amount of fish at once. The dolphins get tangled in these nets while swimming and are dead by the time the net comes up. Several concerned groups want to have laws that make gillnets and hunting dolphins illegal.

[edit] More about dolphins

Dolphins probably rank among the most intelligent marine mammals. The bottlenose dolphin gets its name from its bottle-shaped snout. SIZE: Bottlenose dolphins typically weigh 440 to 600 pounds and reach an average size of 10 feet (some reach as much as 14 feet). HABITS SOCIETY ETC Bottlenose dolphins are very sociably creatures living in a group known as a pod. The number of dolphins to a pod varies significantly. Inshore populations in southern Australian waters generally range from 5 to 20 with offshore groups being much larger, up to 60 Within the pod there is a strong sense of unity or bonding, with lots of interaction (touching, chasing, noises etc) between members happening constantly.

SENSES Bottlenose dolphins have the sense of Sight (both in and out of the water), Hearing (Very good), Taste (they have taste buds) and Touch (they can sense water moving over its body as well as touch and rub each other with fins etc they have a limited sense of smell.

ECHOLOCATION By creating clicking sounds (pulses of ultrasonic sound) and waiting for it to "bounce back" off objects, dolphins can create a "picture" of their surrounds (depending on how long it takes for the click echo to return) This echo-location is primarily used for the locating and hunting of prey.

POPULATION: The exact worldwide population of the bottlenose dolphin is not known. In the eastern tropical Pacific the population is estimated to be 243,500, while in the waters of Japan the population estimates are as low as 37,000.

LIFESPAN: Bottlenose dolphins often live 30 to 50 years.

RANGE: Dolphins can be found in both the Pacific and Atlantic Oceans.

HABITAT: Bottlenose dolphins prefer warm to tropical water.

FOOD: Dolphins consume 13 to 33 pounds of food per day. They feed on a variety of fish, cephalopods (such as squid and octopus), and other sea life. They use echolocation ? bouncing sound off of objects to determine their location ? to hunt and use a series of high-pitched clicks to stun prey.

BEHAVIOR: Bottlenose dolphins are social animals well known for their playful and carefree nature. They sometimes hunt in groups and herd schools of fish toward shore for feeding. Social hierarchies have been noted in dolphin interactions.

OFFSPRING: Females produce one offspring every two to three years after a gestation period of 12 months. Young stay with their mothers for one year. Sometimes, the mother will get help from another female (referred to as an "auntie") in caring for offspring.

THREATS:

Habitat The bottlenose dolphin lives mostly in harbors, bays, lagoons, gulfs, and estuaries . Since there are two different ecotypes of bottlenose dolphins, their habitat differs. The difference between these ecotypes can be seen in the skull, length (body measurements) and the characteristics of their blood. The costal ecotype are usually in the warm and shallow waters, this from of the bottlenose dolphin also lives mainly in harbors, bays, lagoons, and estuaries. The other from of the bottlenose dolphin, the offshore ecotype, it accustom to cooler and deeper waters, they also have certain characteristics in their blood that could indicate this form is well suited for deep-diving. The offshore ecotype also has a larger body, which helps them be able to conserve heat and have the ability to defend itself when it is offended by other predators. The bottlenose dolphin is widely known because of their use in research facilities and marine parks. The bottlenose dolphin migrates thought the seasons to follow the fish's migration. The offshore ecotype migrates in bigger groups than the costal ecotype. The average size for a costal ecotype is about six dolphins, but the offshore ecotype has been known to migrate in groups as big as one-humdred! • In 1990, "Dolphin Safe" labels (certifying that no dolphins were encircled to catch tuna) were placed on tuna cans, reducing dolphin deaths in tuna nets by 97 percent. Pressure from foreign trading nations has weakened the standards of the current label.

• Defenders of Wildlife has filed a lawsuit to help save the dolphins. Write to Secretary Donald L. Evans, Department of Commerce, Washington, DC 20230 and let him know how you feel about actions that may harm dolphins.

• Convention on International Trade in Endangered Species of Wild Fauna and Flora, an international treaty with more than 144 member countries. Appendix I species cannot be traded commercially. Appendix II species can be traded commercially only if it does not harm their survival.

[edit] Did You Know?

  • Dolphins frequently ride the bow wake or the stern wake of boats. They have been seen jumping as high as 4.9 m (16 ft.) out of the water and landing on their backs or sides, in a behavior called a breach.

2. Both young and old dolphins chase one another, carry objects around, toss seaweed to one another, and use objects to invite each other to interact. Such activity may be practice for catching food.

3. Bottlenose dolphins often cooperate when hunting and catching fish. In open waters, a dolphin pod sometimes encircles a large school of fish and herds them into a tight ball for easy feeding. Then the dolphins take turns charging through the school to feed. Occasionally dolphins will herd fish to shallow water where they are easy prey.

4. Bottlenose dolphins generally do not need to dive very deeply to catch food. Depending on habitat, most bottlenose dolphins regularly dive to depths of 3-46 m (10-150 ft.). They are, however, capable of diving to some depth. Under experimental conditions, a trained dolphin dove 547 m (1,795 ft.).


5. Bottlenose dolphins live in fluid social groups called pods. The size of a pod roughly varies from 2-15 individuals. Several pods may join temporarily to form larger groups called herds or aggregations. Up to several hundred animals have been observed traveling in a single herd.


6. The dolphin's sleek, fusiform body, together with its flippers, flukes, and dorsal fin, adapt this animal for ocean life. A dolphin's forelimbs are pectoral flippers. As it swims, a dolphin uses its pectoral flippers to steer and, with the help of the flukes, to stop.

7. Bottlenose dolphins routinely swim at speeds of about 5-11 kph (3-7 mph).

8. On average, a dive may last 8-10 minutes.

9. Group composition and structure often are based on age and sex. Adult males tend to group together in pairs or in threes. Females with calves associate with one another. Individuals may leave one group and join another.

10. Adults eat about 4-5% of their body weight per day. Bottlenose dolphins often cooperate when hunting and catching fish. In open waters, a dolphin group sometimes encircles a large school of fish and herds them into a tight, dense mass for easy feeding. The dolphins take turns charging through the school to feed while the others keep the fish from scattering. Occasionally dolphins herd fish to shallow water and trap them against a shore or sandbar


[edit] References

  • The Bottlenose dolphin: Help us save them
  • Bottlenose Dolphin
  • Bottlenose Dolphins
  • Rare Sighting Of Threatened Bottlenose Dolphins In English Channel -- Science Daily
  • Alternative oil for a new lease of life to Gangetic Dolphins!
  • Animal Bytes -- Bottlenose Dolphin