Mention the word shark to someone on the beach and you are sure to get a reaction (反应). Sharks have been the most feared predator (捕猎者) of ocean. Sharks are fish. They can be found in oceans all over the world, and they have also been found in some rivers and lakes.
One difference between most other fish and a shark is that most fish have bones and a shark has cartilage. Another difference is that the shark is only able to swim forward, while most fish can swim forwards and backwards. Fish also generally have slippery scales (滑溜的鱼鳞), while a shark has rough scales that feel like sandpaper.
In fact, there are about 368 different types. The differences include color, habitat, behavior, and size. Sharks are also known for their very sharp teeth. Instead they swallow large chunks of food. They have five rows of teeth. If a tooth is broken, it is replaced by another tooth.
Sharks are carnivores, meaning that they eat meat. It seems like sharks attack (攻击) people a lot, but chances of getting stung by a bee or getting hit by lightning are greater. Even so, experts say it is important to keep an eye out for sharks when swimming in the ocean.
| A. Sharks do not normally attack people. B. There are many different types of sharks. C. They do not use their teeth to chew their food. D. Cartilage is tough, but it is not as strong as bone. E. They have been around since the time of dinosaurs. |
