我要关于大白鲨的英文资料
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发布时间：2022-04-21 04:08
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热心网友
时间：2023-09-09 05:55
The White Shark: Introction (介绍)
Many paleontologists are very interested in living groups, because the study of the living organisms can both unlock their evolutionary history and provide important keys towards interpreting their fossil record. Some living groups have ancient histories. For example, sharks have existed as a group for over 350 million years! Today, sharks and rays (elasmobranchs) are represented by over 600 species that show a remarkable range of ecological and morphological diversity. Unlike the true fishes, sharks do not have internal bone, but instead have a cartilaginous skeleton. Although many people are told that sharks are primitive in comparison to other groups, this is not true. Many sharks are efficient and specialized hunters that have thrived for millions of years.
This small exhibit shows an amazing predator: the great white shark (Carcharodon carcharias). The white shark is found in temperate waters throughout the world's oceans, and it is an important, though not common, predator in California's coastal habitats. Scientists from several organizations throughout California including the Point Reyes Bird Observatory, the Marine Mammal Center, the California Academy of Sciences, Bodega Bay Marine Laboratory, California Department of Fish and Game, and the Museum of Vertebrate Zoology at UC Berkeley, have been studying white sharks and their prey for several years in hopes to better understand their behavior and ecology.
Food and Feeding（觅食?) Behavior (行为)
White sharks are predatory animals that begin life by feeding on fish, rays, and other sharks, and as they grow, switch to feeding on marine mammals and scavenging on large animal carcasses. Their first mammalian prey are usually the small harbor seal, but as the sharks increase in size, they become large enough to eat sea lions, elephant seals, and small toothed whales. Attack strategy consists of a swift, surprise attack from below, inflicting a large, potentially fatal bite. The pinniped often dies from massive trauma or blood loss, but the bites may be superficial or misplaced on the body, allowing the seal to escape and survive the attacks with their scars as witness. Large white sharks will also scavenge on the carcasses of whale sharks, and on the fat-rich blubber layer of dead whales. They will occasionally feed on sea turtles and sea otters, and are known to attack, but not eat, humans.
Habitat(栖息地) and Distribution{;(生物的)分布区域}
The waters off central California offer a rich bounty of food for white sharks, and every summer and fall they actively feed in nearshore areas. The Farallon Islands, a national wildlife refuge about 27 miles off San Francisco, is a common feeding ground for the sharks. Four species of pinnipeds, the northern elephant seal, the California sea lion, the Steller sea lion, and the harbor seal, live around and breed on these islands, making a plentiful food resource for the white sharks. The coastal waters along central California, especially around the Año Nuevo State Reserve and along the Marin Headlands, is another common feeding area for the sharks. In the summer the sharks feed on seals and sea lions along the coast as far north as Oregon and occasionally the Gulf of Alaska, and in the Fall, they turn south and feed along the offshore islands. It is believed that female white sharks migrate to southern California to give live birth to their offspring. In abnormally warm-water (El Niño) years, white sharks are more plentiful off central California because both they, and their prey, are shifted north. The years 1984-84 and 1991-92 show high trends in white shark predatory activity, and were the warmest oceanic seasons in recent history.
http://www.google.com/search?hl=en&q=+white+shark 英文搜索
http://dict.baidu.com/ 词典
热心网友
时间：2023-09-09 05:56
帮你找了一篇鲨鱼的介绍，难度适中，希望我的回答对你有所帮助！^_^
When you think of sharks, you probably think of big jaws and teeth. That is what sharks are known for. Sharks are also known for their skill in hunting prey (animals they eat). But some sharks don’t hunt, and some have really small teeth. The largest sharks, the whale shark and the basking shark, use a kind of strainer, instead of teeth, to catch food. These sharks strain tiny plants and animals out of the water that enters their mouths as they swim.
SHARKS ARE FISH
A shark is a fish that lives in the sea. Sharks have lived on Earth for almost 400 million years. Today, there are about 375 species (kinds) of sharks. The smallest is the dwarf dogfish, less than 8 inches (20 centimeters) long. The huge whale shark can be more than 50 feet (15 meters) long.
Sharks, like all fish, are vertebrates (animals with a backbone). A shark’s skeleton, however, is not made of bone. It is made of a bendable material called cartilage.
Sharks, like other fish, are cold-blooded. They do not make their own body heat.
WHERE SHARKS LIVE
Sharks live in seas all over the world. Most sharks live in warmer waters. However, sharks have been spotted near the North and South poles.
Sharks live in salt water, but some can live for a while in fresh water. Bull sharks, for example, can swim up the Mississippi River.
Some kinds of sharks live in shallow water along coastlines. Other sharks live far out in the open ocean. A few species live deep down in the sea.
A SLEEK BODY
Sharks have long, streamlined bodies that taper in front and back. This shape lets sharks glide gracefully through the water. It also helps them put on great bursts of speed.
Most shark species have bodies that are from 3 feet (1 meter) to 6 feet (2 meters) long. The best-known sharks, however, are the biggest sharks. Hammerheads, tropical sharks with T-shaped heads, can be 12 feet (3.5 meters) long. Great white sharks are often more than 20 feet (6 meters) long.
A shark’s body may look smooth, but it is actually covered with tiny, rough scales. These scales feel like sandpaper to the touch.
HOW SHARKS SWIM
Sharks have several fins that help them swim. Their dorsal fins keep them steady in the water. Fins behind the head help them turn and move up and down. Fins near the tail help keep them level. The big tail fin, however, is what really makes a shark go fast.
If a shark stops swimming, it will fall to the sea bottom. Unlike other fish, a shark does not have a swim bladder. An air-filled swim bladder helps fish float.
BREATHING
Most sharks have to keep swimming in order to breathe. Like all fish, a shark breathes through its gills. Gills take oxygen out of the water. All animals need oxygen in order to live.
Unlike other fish, a shark does not have the muscles to pump water through its gills. Sharks have to move in order for water to enter the gill slits on the sides of their heads.
TEETH AND JAWS
Most sharks have powerful jaws and rows of sharp, triangular teeth. They use their teeth and jaws to crush their prey or tear out pieces of flesh.
Your teeth are anchored in your jaw. A shark’s teeth are set into its gums. Sharks often lose teeth while eating. However, there are always rows of new teeth growing behind the first set. As a shark loses teeth, new ones move forward to replace them.
SHARK SENSES
A shark’s sense of smell is so powerful that it can detect odors in the water hundreds of meters away. Sharks’ eyes detect very small movements and can see in dark waters.
Sharks, like other fish, have a special sense called the lateral line, which runs around the side of the body and into the head. It can sense the tiniest vibrations in the water caused by sounds or animal movements. Sharks can also sense weak electrical currents from nerves and muscles in living animals.
HOW SHARKS REPRODUCE
Females in some shark species lay eggs outside their bodies. Others keep the eggs in their bodies until they hatch. Still others give birth to live young much the way mammals do.
Sharks have between and 1 and 20 babies, or pups, at a time.
HUNTING AND EATING
Fish is the favorite food of most meat-eating sharks, along with shellfish. Great white sharks will sometimes eat larger prey, such as seals, dolphins, whales, and other marine mammals.
Sharks play an important role in keeping ecosystems in balance. Sharks often eat weak or diseased animals. Biologists fear that without sharks, the number of other animals in the sea would quickly grow out of control and eat all the food. It might take many years to restore the delicate balance that sharks help maintain.
SHARKS AND PEOPLE
Sharks have a reputation for attacking people, but these attacks are rare. One study showed that there are fewer than 100 shark attacks worldwide in a year. Most of the victims do not die. Researchers believe that sharks often attack humans by mistake, thinking that they are prey.
People are actually a bigger threat to sharks. Humans hunt sharks for sport, food, medicine, and leather (skin). Shark meat and shark-fin soup are popular in many places around the world. Some people hunt sharks just for their fins, throwing the rest of the shark back in the sea to die. Because of this, some sharks have become endangered. Scientists are trying to decide how best to protect sharks so they won’t disappear.
热心网友
时间：2023-09-09 05:56
great white shark..type it into yahoo.com..
