英語聽力文摘470 昆蟲界的“投彈手”

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BombardierBeetle

投彈手甲蟲

Male：Is it a beetle or some sort?

Female:Right in deed.It's a bombardierbeetle.This one is an African species, but it could be found on most other continents too.

M:Bombardier? He releases bomb or some sort?

F:He may look harmless, but when threatened, this little guy fires a rapid spray of boiling hot, toxic chemicals that can kill an insect attacker. The release of the chemicals makes an explosive popping sound, like a tiny bomb detonating.

These beetles are great marksmen, too. The chemicals are released from its abdomen, which it can rotate to adjust its aim. There is no part of the beetle’s body that a predator can safely attack.

M:How do this hot,toxic not injure or kill the beetle from the inside?

F:The toxicity and heat are not constant inside the beetle, but are produced by a binary chemical reaction. This means that the toxicspray is a combination of two main chemicals that are relatively harmless on their own.

They’re stored in separate compartments in the beetle’s body until it needs them. Then they’re both released into a different compartment called the reaction chamber, where the chemicals are mixed together with enzymes.

Heat accumulates, but the chamber wall is thick so as to not allow the heat to transfer into the insect’s body. Pressure accumulates too, and so the mixture quickly explodes out from the chamber. Though the toxin can be deadly to some insects, it’s a relatively small amount compared to the size of the beetle.

男:它是甲蟲還是什么?

女:就是甲蟲，它是一只投彈手甲蟲。雖然它是非洲品種，卻也能在其它大多數(shù)洲找到。

男:投彈手?它會放炸彈還是怎么的?

女:這個小東西看起來是無害的，但受到威脅時就會放出沸騰的熱水噴霧，和可以殺死攻擊它的昆蟲的有毒化學物質。該化學物質釋放時會發(fā)出一陣很大的爆炸聲，就像一個小炸彈被引爆了。

這些甲蟲還是偉大的射手。它們從腹部釋放(有毒)化學物質，腹部可以轉動以調整(瞄準)目標。而且它們的捕食者沒有誰能在攻擊這些甲蟲后毫發(fā)無損。

男:為什么這些在甲蟲體內的熱的、有毒的物質并沒有傷害或者是殺死它們呢?

女：這些熱的有毒物質在甲蟲體內并不是恒定不變的，它們是一個二元化學反映的產物。這就意味著該有毒噴霧是兩種對甲蟲本身就無害的化學物質的化合物。

它們被儲蓄在甲蟲體內的不同區(qū)域。直到被需要時它們就會釋放到一個叫做“反應室”的不一樣的地方。在這里，化學物質就會與酶混合。

熱量在累積，但是由于反應室壁很厚，熱量就不能傳輸?shù)嚼ハx體內。壓力也在累積，所以導致混合物在室內快速發(fā)生爆炸。盡管該毒物對于一些昆蟲而言是致命的，但是相較于甲蟲的體形，它的量還算是小的。

New wors:

predator：n. [動] 捕食者;掠奪者

toxin:n. 毒素;毒物