英语阅读海豚dolphins课件

Risso's Dolphin
bottlenose dolphin
Orca Killer Whale
Commerson's dolphin
Dusky dolphin
Indo-Pacific hump-backed dolphin Sousa chinensis
Behavior
Intelligence
＊Dolphins can establish strong social bonds; they will stay with injured or ill individuals, even helping them to breathe by bringing them to the surface if needed.
Military
• finding mines • rescuing lost or
trapped humans
Cuisine
Dolphin meat is consumed in a small number of countries worldwide, which include Japan and Peru.
Social behavior
＊Dolphins are social living in pods of up to a dozen individuals. In places with a high abundance of food, forming a super grouping may exceed 1,000 dolphins.
Dolphins are often regarded as one of Earth's most intelligent animals, though it is hard to say just how intelligent. Comparing species' relative intelligence is complicated by differences in sensory apparatus, response modes, and nature of cognition.
Natural threats
Except for humans, dolphins have few natural enemies. • A few of the larger sharks, such as great white shark • A wide variety of diseases and parasites
Dolphins
Dolphin
Dolphins are marine mammals closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, eating mostly fish and squid.
Pollution
• Pesticides • Heavy metals • Plastics • Industrial and agricultural pollutants
noise
Loud underwater noises, such as live firing exercises, or certain offshore construction projects, such as wind farms, may be harmful to dolphins, increasing stress, damaging hearing, and causing decompression sickness by forcing them to surface too quickly to escape the noise.
Fra Baidu bibliotek
Therapy
Therapy for psychological problems and developmental disabilities. For example, a 2005 study found dolphins an effective treatment for mild to moderate depression.
Relationships with humans
Mythology
Dolphins have long played a role in human culture. Dolphins are common in Greek mythology and there are many coins from ancient Greece which feature a man or boy or deity riding on the back of a dolphin.
Hunting
Various fishing methods, the use of drift and gill nets, unintentionally kill many dolphins. In some parts of the world, such as Taiji in Japan and the Faroe Islands, dolphins are traditionally considered as food.
Movie The Cove
Partner
Rachel Jennifer
Friends of humans
Dolphins are friends of human beings, they are happy to be with people. Assist fishermen fishing; Have many reports about dolphins to save people; One report in 1959,even said that dolphins drove sharks away, then saved the victims of the passengers.
Sleeping
Generally, dolphins sleep with only one brain hemisphere in slow-wave sleep at a time, thus maintaining enough consciousness to breathe and to watch for possible predators and other threats.
Jumping
Dolphins occasionally leap above the water surface, and sometimes perform acrobatic figures. Scientists are not certain about the purpose of the acrobatics. Possibilities include locating schools of fish by looking at abovewater signs like feeding birds, communicating with other dolphins, dislodging parasites or simple amusement.
Vocalizations
Roughly three categories of sounds can be identified: • frequency modulated whistles • burst-pulsed sounds • clicks. Dolphins communicate with whistle-like sounds produced by vibrating connective tissue, similar to the way human vocal cords function and through burst-pulsed sounds.
Threats
Human threats
Some dolphin species face an uncertain future, especially some river dolphin species such as the Amazon river dolphin, which are critically or seriously endangered.
Playing
Play is an important part of dolphin culture. Dolphins play with seaweed and play-fight with other dolphins. At times they harass other local creatures, like seabirds and turtles.