The Venus flytrap is a carnivorous plant well known for its ability to lure insects (and arachnids) into its “capture organ.” Once they enter there is no escape. The organ shuts tight and the digestion process begins. Dionaea muscipula, the actual name of the Venus flytrap, is native to small, wetland areas in North and South Carolina, however, people have taken a shine to it as a houseplant so it is now grown in many other locations.
This exotic plant is now considered by the United States to be endangered in the wild due to habitat destruction caused by land development and the creation of barriers to curtail forest fires. Recent efforts have been aimed at protecting the Venus flytrap from these threats but the plants continue to be stolen from their natural habitat to be sold illegally by “Venus flytraps poachers” despite that this is a felony in North Carolina and can result in a prison sentence.
Venus flytraps tend to live in nutrient-poor soil, which is why they rely on insects to help them survive. Ants, beetles, grasshoppers, flying insects, and even spiders are on the menu!
Let’s delve a bit deeper into how the plant traps insects. It starts with the plant releasing a large number of volatile and fragrant organic compounds into the air that are attractive to insects. The hypothesis is that these volatile compounds may be the initial source of attraction and serve to bring the insects closer to the plant. Once the bugs approach one of the plant’s traps found at the end of each leaf, they are lured inside by a sweet-smelling, fragrant nectar secreted by the traps. The inside of the traps is covered with a red pigment that may also play a role in inviting insects into the deadly chamber.
When an insect enters, sensory hairs are disturbed and an electrical signal known as an action potential is triggered. If two or more such signals occur in a 20-30 second span, the trap clamps shut in less than a second although not completely. It takes even more action potentials caused by the struggling prey deflecting more sensory hairs for complete entrapment. The closure is helped by the detection of insect secretions such as uric acid, potassium ions, and sodium ions. This additional step ensures that it is an insect or arachnid, rather than some inanimate substance such as a raindrop or a seed that is stuck in the trap.
After the plant has detected that it has indeed captured a living prey, specialized glands are activated and begin to release a mixture of acidic digestive juices to decompose the victim into compounds that are useful to the plant. Chemicals containing nitrogen, phosphorous, and sulfur, essential for the plant’s growth, become available to supplement the nutrients available from the soil.
Once a Venus flytrap has closed, it remains shut for 5 to 12 days while it digests its prey. When done, only the insect’s exoskeleton remains. The trap opens, the exoskeleton is expelled and the Venus flytrap is ready for its next meal.
Caitlin Bard is completing her Bachelor of Science with a major in neuroscience at McGill University.
