The Venus Fly Trap (Dionaea muscipula) is the single representative of carnivorous plants which prey on insects using a snap-mechanism. Native to the central southeastern coastal plain of the United States, the plant is largely restricted to bogs of this area due to its competitive advantage in nutrient limited habitats. Nitrogen limitations in bog habitats have allowed the Venus Fly Trap to out-compete other plants by creatively getting the resource not from the soil, but from insects! The plant does this by trapping and digesting bugs in their glove like modified leaves. The picture below shows the Venus Fly Trap (and its trapping mechanism) in its natural habitat.
The trapping mechanism of the plant is set in motion once an insect flies into the trap and sets off the “trigger hairs” on the inside (see below pictures). Once at least two trigger hairs have been activated by the insect’s movement the trap will close.
After activation of the trigger hairs, an “osmotic motor” operates at the hinge of the trap. The activation of the second trigger hair causes an electrical transduction single to the hinge of the trap, which signals the cells to intake a large quantity of positive ions. This changes the water potential of the cells and causes water to rush in and the trap closes as the cells swell and change shape, acting as an osmotic motor. The speed of this closure was made note of by Charles Darwin and has since been heavily studied (Volkov et. al. 2008). The trap will remain closed for several days as enzymes are released around the insect to digest it and nutrients are absorbed. Each trap can activate and digest insects multiple times, but after about seven cycles the leaf will die and a new one will grow. The image below shows an insect with only the nutrient poor exoskeleton remaining after digestion.
The reproduction of the Venus Fly Trap is often overlooked. Producing seeds the size of a sentence period, the plant must hold its flowers high above the traps so that pollinating insects do not get caught (picture below). The plant can also reproduce asexually through rhizome generation of a new plant.
Dionaea muscipula – The Venus Flytrap. (n.d.). Retrieved November 23, 2014, from http://botany.org/Carnivorous_Plants/venus_flytrap.php
Volkov, A.G., Adesina, T., Markin, V.S., and Jovanov, E. 2008. Kinetics and Mechanisms of Dionaea muscipula Trap Closing. Plant Physiology. 146: 694-702