PLANET EARTH Jungles

The secret of success in the competitive jungle is specializing and this has led to the evolution of some very intimate relationships between plants and animals. These are pitcher plants（猪笼草） also from Borneo. Adapted to living in very low nutrient soils the pitcher plant gets most of its nourishment from insects lured to nectar glands on the underside of the lids.



Once onboard, the waxy sides of the pitcher ensure there's little chance of escape. Most slip to a watery grave. At the bottom of the pitcher glands secrete enzymes（酶） which help to digest（消化） the corpses（尸体）, so feeding the plant. But not all visitors have a fatal attraction to the pitchers. The red crab spider（红蟹蜘蛛） spends its entire life in the pitchers, hanging on with threads of silk.



Instead of building a web, it relies on the water filled pitcher to trap it's food. When an ant falls in, the spider simply waits for it to drown and then abseils down（沿着绳线下滑） for a spot of fishing. Alive, this ant would be far too dangerous for the spider to tackle so, using the pitchers as traps, means it can get bigger meals and the spider doesn't rob the pitcher of everything.