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A Venus flytrap counts: it snaps shut only when the tiny trigger hairs inside its trap are touched twice within about 20 seconds. The trap closes in about a tenth of a second, and digestion starts only after further touches show that live prey is struggling inside.

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The plant is native only to the coastal wetlands of North and South Carolina, where the soil is poor in nutrients, so insects and spiders supply the nitrogen it lacks. Each touch of a trigger hair fires an electrical signal similar to a nerve impulse. In 2016 Rainer Hedrich's team at the University of Würzburg in Germany showed how the counting works: two signals close the trap, and further signals switch on the genes for digestive enzymes, so the more the prey struggles, the more enzymes the plant makes. The rule stops the plant wasting energy on raindrops or windblown debris. Digestion takes about ten days, after which the trap reopens. Charles Darwin studied the flytrap closely for his 1875 book Insectivorous Plants and called it one of the most wonderful plants in the world.

Türkçe oku
Venüs sinekkapanı sayar: Tuzağının içindeki minik tetik tüylerine yaklaşık 20 saniye içinde iki kez dokunulmadıkça kapanmaz. Tuzak saniyenin onda biri kadar kısa bir sürede kapanır; sindirim ise ancak ardından gelen dokunuşlar içeride canlı bir avın çırpındığını gösterince başlar.

Bitkinin doğal yurdu yalnızca ABD'deki Kuzey ve Güney Carolina'nın kıyı sulak alanlarıdır. Buranın toprağı besince fakir olduğundan, bitki eksik kalan azotu böceklerden ve örümceklerden sağlar. Tetik tüylerine yapılan her dokunuş, sinir uyarısına benzeyen elektriksel bir sinyal üretir. Almanya'daki Würzburg Üniversitesi'nden Rainer Hedrich'in ekibi 2016'da bitkinin nasıl saydığını gösterdi: İki sinyal tuzağı kapatır, sonraki sinyaller ise sindirim enzimlerinin genlerini devreye sokar; av ne kadar çırpınırsa bitki o kadar çok enzim üretir. Bu kural, bitkinin enerjisini yağmur damlalarına ya da rüzgârın getirdiği çerçöpe harcamasını önler. Sindirim yaklaşık on gün sürer, ardından tuzak yeniden açılır. Charles Darwin, 1875'te yayımlanan Insectivorous Plants (Böcekçil Bitkiler) adlı kitabı için sinekkapanını yakından incelemiş ve onu dünyanın en harika bitkilerinden biri olarak nitelemişti.

Sources and further reading

Background reading: Venus flytrap
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