鲨鱼英文作文了解到了什么，鲨鱼的英文介绍加中文翻译
鲨鱼英文作文了解到了什么，鲨鱼的英文介绍加中文翻译
Sharks are a type of fish.
There are hundreds of kinds of sharks.Most are about two meters long.The dogfish shark,however,is less than twenty centimeters in length.The biggest whale shark can grow to twenty meters in length.Sharks do not have bones.The skeleton of a shark is made of cartilage.Human noses and ears are also made of cartilage.
A shark has an extremely good sense of smell.It can find small amounts of substances in water,such as blood,body liquids and chemicals produced by animals.Sharks also sense electrical and magnetic energy linked to nerves and muscles of living animals.
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Sharks (superorder Selachimorpha) are fish with a full cartilaginous skeleton[1] and a streamlined body. They respire with the use of five to seven gill slits. Sharks have a covering of dermal denticles to protect their skin from damage and parasites and to improve fluid dynamics.[1] They have replaceable teeth. They are some of the world's most misunderstood predators, as they very rarely attack humans unless intimidated.
Sharks include species from the hand-sized pygmy shark, Euprotomicrus bispinatus, a deep sea species of only 22 centimetres (9 inches) in length, to the whale shark, Rhincodon typus, the largest fish, which grows to a length of approximately 12 metres (41 feet) and which, like the great whales, feeds only on plankton through filter feeding. The bull shark, Carcharhinus leucas, is the best known of several species to swim in both salt and fresh water (it is found in Lake Nicaragua, in Central America) and in deltas.[2]
鲨鱼属于脊椎动物门软骨纲(Chondrichthyes)板鳃亚纲，海生，少数种类进入淡水，为一群游速快的中大型海洋鱼类。
Sharks are vertebrates steel door cartilage (Chondrichthyes) elasmobranchii, Marine, a few species enter fresh water, as a group of large Marine fish speed is fast.
鲨内骨骼完全由软骨组成，常钙化，但无任何真骨头组织，外骨骼不很发达或退化，身体常被皮齿(质鳞)，牙多样化，具有硬肌，但膜骨则永不存在，脑颅无缝。
Shark endoskeleton completely composed of cartilage, often calcified, but without any true bone tissue, degraded or exoskeletons is not very rich, the body is often skin teeth (scale), tooth diversification, with hard muscle, but never exist, membrane bone temple seamless.
上额由腭方软骨组成，下额由梅氏软骨组成。最新研究表明，鲨体内含有多种生物活性成分，如抗癌因子、角鲨烯、黏多糖等等。
On the forehead is composed of palatal side cartilage, the forehead is composed of Mr Medvedev cartilage.Sharks, according to new research in the body contains a variety of biological active ingredients, such as anti-cancer agent, squalene, mucopolysaccharides and so on.
扩展资料
鲨鱼的起源不详，但其地质学纪录可追溯到泥盆纪(4.08亿～3.6亿年前）。鲨鱼化石在中泥盆世出现，在石炭纪（3.6亿～2.86亿年前）成为占优势的脊椎动物。现代鲨鱼出现于侏罗纪早期（2.08亿～1.87亿年前），到白垩纪（1.44亿～6,640万年前）已经发展成现存的各科。
总之，除觅食和游泳机制的改进外，进化对鲨鱼的形态改变甚微。无论对化石种和现存种类来说，牙齿在鲨鱼种类鉴别方面均有很重要作用。
参考资料来源：百度百科-鲨鱼
