The Venus Fly Trap

What has a gaping red mouth, long fearsome teeth, and can snap food from the air in the blink of an eye? A dragon? Some frightening beast? Few people would guess that this frightening creature is the humble Venus fly trap, a plant smaller than the size of your hand.

The fleshy “mouth” of a fly trap is not like the mouths of people or dogs or any other creatures. This trap is made of a tough plant fiber and snaps shut when crawling or flying insects brush past. Unlike many other carnivorous creatures, which have complex systems for processing food, all of the work of digestion in a Venus fly trap happens in its leafy trap. First, the trap has to ensure that insects cannot easily escape to freedom. Long tooth-like pieces called cilia frame the opening of the trap. The cilia cage the insects and prevent them from escaping the trap’s leafy jaws. From here, the fly trap faces a challenge. In the wild, pieces of debris can fall from passing animals and other plants to trigger the trap. Instead of wasting precious energy on inedible objects, the plant waits to feel the object move before beginning digestion. If the object is still, the trap will soon open and release the debris. The plant can then await its next victim. If a live insect is sensed, however, the trap will flood with wet digestive juices that will break down the body of its victim into usable nutrients.

Scientists believe that the hunt for nutrients is the reason why the ancient ancestors of Venus fly traps evolved methods to attract and digest insects. Venus fly traps and other carnivorous plants most commonly grow in bogs. The soil in boggy habitats is acidic and lacks sufficient nutrients for many plants to grow. It is possible that some bog plants developed a taste for insects as a novel way of obtaining nutrients. The snapping leaves of the Venus fly trap, however, are unique even among carnivorous plants. Other carnivorous plants use slippery leaves or sticky hairs to trap insects. Scientists think that the Venus fly trap is most closely related to the sticky hair type of carnivorous plant. The development of a trap mechanism meant that the Venus fly trap could better hold on to wriggly insect prey than its relatives with simpler sticky mechanisms.