英语听力文摘470 昆虫界的“投弹手”
投弹手甲虫
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:它是甲虫还是什么?
女:就是甲虫，它是一只投弹手甲虫。虽然它是非洲品种，却也能在其它大多数洲找到。
男:投弹手?它会放炸弹还是怎么的?
女:这个小东西看起来是无害的，但受到威胁时就会放出沸腾的热水喷雾，和可以杀死攻击它的昆虫的有毒化学物质。该化学物质释放时会发出一阵很大的爆炸声，就像一个小炸弹被引爆了。
这些甲虫还是伟大的射手。它们从腹部释放(有毒)化学物质，腹部可以转动以调整(瞄准)目标。而且它们的捕食者没有谁能在攻击这些甲虫后毫发无损。
男:为什么这些在甲虫体内的热的、有毒的物质并没有伤害或者是杀死它们呢?
女：这些热的有毒物质在甲虫体内并不是恒定不变的，它们是一个二元化学反映的产物。这就意味着该有毒喷雾是两种对甲虫本身就无害的化学物质的化合物。
它们被储蓄在甲虫体内的不同区域。直到被需要时它们就会释放到一个叫做“反应室”的不一样的地方。在这里，化学物质就会与酶混合。
热量在累积，但是由于反应室壁很厚，热量就不能传输到昆虫体内。压力也在累积，所以导致混合物在室内快速发生爆炸。尽管该毒物对于一些昆虫而言是致命的，但是相较于甲虫的体形，它的量还算是小的。
New wors:
predator：n. [动] 捕食者;掠夺者
toxin:n. 毒素;毒物
