Tuesday, 27 July 2010

Venus Fly Trap

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The Venus flytrap is probably the most famous example of a rather peculiar thing - a meat eating plant. While most plants are passive recipients of sunlight, water and the unwanted attention of herbivores, the Venus flytrap eats living things. And while many meat eating plants, such the pitcher plants, passively attract prey before passively capturing and passively digesting them, the Venus flytrap could be described as something more akin to an ambush predator. Strangely enough, Venus is the Roman goddess of love, so I guess someone was going through some difficult times when they named it.

The other part of their name clearly refers to the way it catches its food. In most plants there is a stem with large leaves at the end of small petioles coming off it. The Venus flytrap is different, the stem is small and under the ground, the petioles are large, flattened and capable of photosynthesis, while the actual leaves are modified into hinged traps. The inside is pigmented red while the edges secrete mucilage, all to attract unwary flies to what they think is small bounty of sustenance.

There are also, however, tiny, unassuming hairs situated right in the midst of this diner. Tiny, unassuming hairs which could well mean death. The Venus flytrap doesn't want to expend energy for nothing, so the fly has a chance... a tiny, unassuming chance. Touch one hair once, and our fly is alright. But touch that hair again in quick succession, or another one within 20 seconds of the first and the trap is sprung. This complication ensures there is no reaction to humdrum articles such as raindrops and detritus. An unwary fly, however, will be the beneficiary of a complex mechanism involving mechanoreception, bioelectrochemical signaling and ion channels (buh??), That is to say, the flytrap shuts (oh, right) in as little as 0.3 seconds. The futile struggling of the insect causes the leaf to close ever tighter, before enzymes are secreted to digest the body and absorb the horrible goodness. After a week or so the trap reopens, revealing a rather gruesome husk of exoskeleton, and is ready for reuse.


This remarkable adaptation means the Venus flytrap need not gain its nutrition from the soil in which it's situated, it lives in nitrogen-poor boggy areas where most other plants can't. While some 5 or so million flytraps are cultivated for people who want it as a pet (sort of thing), its real home is only in North and South Carolina on the eastern coast of the USA, where there are less than 40,000 left in the wild. Can you believe they also produce flowers? To attract pollinators! Excuse me? The flytrap of the Love Goddess... I wonder how it would go down for Valentine's?

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Turns out I can't embed the vastly superior video I had wanted to use, you can see it here.

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