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July 19, 2006

Interesting things

I've been browsing through a biology magazine today which contained a number of interesting articles. Did you know, for example, that no sharks exist below sea levels of 3000 m? Now that's a relief! No, seriously, for quite some time scientists have thought that sharks who are cartilaginous fishes (Chondrichtyes) and therefore belong to the oldest known group of fishes are present in deep sea. Apparently there's a food related reason for this. Sharks do not have a gas bladder to keep them afloat but achieve this with the help of their oil rich liver. The growth of that liver requires a lot of energy, i. e. food, that is simply not present in great depths. Modern bone fish (Osteichtyes) on the other hand do have a gas bladder and have been observed at depths of up to 9000m (29500 ft). Amazing!

I suppose at least the dedicated gardeners among you are aware that plants though rooted to the spot are not as helpless as they look when it comes to defending themselves against enemies. Some of them have quite impressive thorns and some can even start a chemical warfare on their aggressors. Ever been stung by a nettle? And that's just a mild form of defensiv weapon. But did you know that quite a number of plants, among them soybeans, potatoes and tomatoes, try to starve their enemies? They contain proteins which will inhibit the metabolism in the attacking insects. The insects will simply not be capable of breaking down the bits of tomato they have eaten into amino acids and synthesizing the proteins they need themselves from these acids. Instead it leaves them with a tummy bug and a hungry feeling inside.

I have no doubt that the insects have the appropriate countermeasures at their disposal to survive even this. Judging from observation of those living in my garden their numbers never seems to decrease - quite contrary! Ah well, I suppose Nature will find a way of keeping a balance...

Posted by Mausi at July 19, 2006 09:05 PM

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