人教版九全unit13拯救鯊魚原文
人教版九全unit13拯救鯊魚原文
鯊魚，生活在海洋中，是海洋中的魚類。接下來學(xué)習(xí)啦小編為你整理了人教版九全unit13拯救鯊魚原文，一起來看看吧。
人教版九全unit13拯救鯊魚原文
Many have heard of shark’s fi n soup. Th is famous and expensive dish is especially popular in southern China. But do you realize that you’re killing a whole shark each time you enjoy a bowl of shark’s fi n soup?
When people catch sharks, they cut off their fi ns and throw the shark back into the ocean. Without a fi n, a shark can no longer swim and slowly dies. Th is method is not only cruel, but also harmful to the environment. Sharks are at the top of the food chain in the ocean’s ecosystem. If their numbers drop too low, it will bring danger to all ocean life. Many believe that sharks can never be endangered because they are the strongest in their food chain. But in fact, around 70 million sharks are caught and traded in this industry every year. Th e numbers of some kinds of sharks have fallen by over 90 percent in the last 20 to 30 years.
Environmental protection groups around the world, such as WildAid and the WWF, are teaching the public about “fi nning”. Th ey have even asked governments to develop laws to stop the sale of shark’s fi ns. So far, no scientifi c studies have shown that shark’s fi ns are good for health, so why eat them? Help save the sharks!
Many have heard of shark’s fin soup. This famous and expensive dish is especially popular in southern China. But do you realize that you’re killing a whole shark each time you enjoy a bowl of shark’s fin soup?When people catch sharks, they cut off their fins and throw the shark back into the ocean. Without a fin, a shark can no longer swim and slowly dies. This method is not only cruel, but also harmful to the environment. Sharks are at the top of the food chain in the ocean’s ecosystem. If their numbers drop too low, it will bring danger to all ocean life. Many believe that sharks can never be endangered because they are the strongest in their food chain. But in fact, around 70 million sharks are caught and traded in this industry every year. The numbers of some kinds of sharks have fallen by over 90 percent in the last 20 to 30 years.Environmental protection groups around the world, such as WildAid and the WWF, are teaching the public about “finning”. They have even asked governments to develop laws to stop the sale of shark’s fins. So far, no scientific studies have shown that shark’s fins are good for health, so why eat them? Help save the sharks!
人教版九全unit13拯救鯊魚翻譯
拯救鯊魚!
很多人聽說過魚翅湯。這道著名且昂貴的菜肴在中國南方尤其流行。但是你們意識到每次你享受一碗魚翅湯時，你都在殺死一整只鯊魚?
人們捕捉鯊魚時，他們砍掉它們的魚翅，然后再把鯊魚放在海里。這個方式不僅殘忍，還對環(huán)境非常有害。沒有了魚翅，鯊魚在也游不動，會慢慢死掉。鯊魚在海洋的生態(tài)系統(tǒng)中處于食物鏈的頂端，如果它們的數(shù)量降至過低，會給所有海洋生命帶來危險。很多人相信鯊魚不會陷入危險中，因為它們是食物鏈中最強大的，但事實上，每年在這個產(chǎn)業(yè)中大約有7000萬鯊魚被捕捉和交易。在過去20到30年中，有些種類的數(shù)量已經(jīng)減少百分之九十以上。 世界各地的環(huán)保團體，例如野生救援會和世界自然基金會，教育公眾有關(guān)“獵翅”的行為。它們甚至已經(jīng)要求政府部門制定切當(dāng)?shù)姆蓙礓N售鯊魚翅。到目前為止，沒有科學(xué)研究顯示鯊魚翅對于健康的好處，因此為什么要吃它們呢?幫忙拯救鯊魚吧!
鯊魚的自然生長
和多數(shù)動物一樣，鯊魚是有性繁殖。鯊魚的交配行為非常復(fù)雜，不同種類的雄性和雌性鯊魚在交配前的例行程序也有很大的分別。結(jié)伴同游，撕咬和顏色變化等行為模式是共有的。姥鯊等種類的鯊魚采用復(fù)雜的成群環(huán)游的行為，還不了解這一行為的目的。
在雌雄鯊魚成功交配、同時雌性鯊魚體內(nèi)的卵子完成受精之后，這一種屬鯊魚的受精卵就會以下列三種方式中的某一種繼續(xù)發(fā)育：
1.卵生：卵生鯊魚產(chǎn)下帶有厚厚的卵鞘的卵，使它們能夠附著在巖石或者海藻上，并抵抗捕食者。一般是大型鯊魚采用。鯊魚的卵很大，營養(yǎng)供應(yīng)不虞匱乏。大多數(shù)的卵鞘呈寬廣的矩形。排出的卵包在扁平的墊形鞘內(nèi)，而墊形鞘是卵在通過輸卵管時四周加上去的，鞘的外皮于進(jìn)入水中后會變硬，鞘的每個角落都有一個短而中空的角狀物，海水能由此進(jìn)入，使卵獲得氧氣。母鯊魚每次排卵數(shù)目有限。卵呈布袋狀或螺旋狀，產(chǎn)出后被固定于珊瑚礁、海底植物或石縫中。被沖上海岸的短吻棘鮫的空卵囊，則被昵稱為“美人魚的小錢包”。這些卵在幾天或幾星期后孵出，鯊魚就會離開幼仔讓它們獨立生存。
2.卵胎生(非胎盤型胎生)：此類鯊魚也養(yǎng)護體內(nèi)的胚胎，然后產(chǎn)出活的幼仔，但它們不能向它們的后代提供任何直接的營養(yǎng)。某些種類的鯊魚，如鯖鯊使用“奧佛吉(oophagy)”的方式，即鯊魚媽媽產(chǎn)出一串小的沒有受精的卵，被生長中的胚胎吃掉。受精卵在子宮中發(fā)育，以卵黃囊或由卵巢排入子宮的卵為營養(yǎng)來源，在子宮中并不形成胎盤。除鯨鯊每次可產(chǎn)300尾以上外，其余每次頂多數(shù)十尾，最少的是狐鮫(長尾鯊)，每次只產(chǎn)兩尾。相反，孕育中的鯊魚依賴于卵的卵黃囊維持生計。
3.假胎生(胎盤型胎生)：外包角質(zhì)殼的受精卵于子宮中發(fā)育，成長所需的營養(yǎng)由卵黃囊胎盤得，后期在雌性鯊魚的子宮內(nèi)通過胎盤或一種稱為子宮液的分泌物吸取營養(yǎng)物質(zhì)，直到幼鯊幾乎完全成形才產(chǎn)出，每次產(chǎn)數(shù)十尾。胎生確保幼仔在生長期間得到很好的孕育，因此出生后能夠立刻在嚴(yán)酷的大海中生存。遠(yuǎn)洋的大部分鯊魚都是胎生。大部分鯊魚每年按照季節(jié)進(jìn)行繁殖，一些大型鯊魚隔年繁殖。大部分鯊魚懷孕期達(dá)8～9個月，白斑角鯊的懷孕期甚至高達(dá)24個月。一般而言，大型鯊一次生產(chǎn)較多小鯊，小型鯊則相反。鯊魚的生長也異常緩慢，直到5～10歲才算性成熟。鯊魚是地球上最早的通過兩性交配體內(nèi)受精孕育繁殖的動物。
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