Antirainforests
an eerie feeling overwhelms you, the moment you step inside a rainforest. There are ants all over, hundreds of thousands of them crawling in the deep woods. The situation becomes creepier if you know they exist in abundance by defying the laws of nature.
Ants are supposed to be carnivores, so they should be near the top of the foodchain. By and large, each link in the web of life is a tenth the size of the one before it. This is because 90 per cent of the energy generated by the creatures in each link is used for metabolic processes, rather than being converted into flesh, blood, bones or exoskeletons. But a rainforest has more ants than arthropods (insects, spiders and other creepy-crawlies, that are devoured by the wingless creatures). Clearly, something strange is going on. Diane Davidson of the us-based University of Utah and her colleagues believe they know what it is: ants are not carnivores. Instead, they are crypto-vegetarians.
Davidson's theory is that most ants get their essential nitrogen from liquids exuded by sap-sucking insects, and not from gobbling other animals. "Ants can't get the liquids straight away from plants, as they have nasty chemicals to protect them from leaf-chewing herbivores. But the sapsuckers (treehoppers and scale insects) are unique because they bypass those defences. They have a tiny