In the plant kingdom, there is a special group of plants that has sparked the imagination of many a science fiction writer. These plants, indeed, cause all of us to stop and look at them with a renewed sense of wonder at the great things the Lord has done. These plants are meat eaters — carnivorous plants. This is a characteristic that God gave these plants to help them obtain vital minerals in swampy soil low in nutrients. They include, among others, the Pitcher plant, the Sundew (which lives in West Virginia) and the most famous, the Venus Fly Trap. Let’s look at how this plant is able to detect and then catch something as elusive as a fly.
The Venus Fly Trap is a rather small plant, generally only growing four or five inches tall. It does carry on photosynthesis and so is a true plant, but the soil in which it is designed to grow is very low in necessary minerals, so the plant just catches them. The structure that it uses is a modified leaf. It is hinged at the middle to form a trap. The outside of the trap is lined with long pike-like extensions that form a nice barred cage long before the trap has completely closed. The inside of the trap is lined with very important trigger hairs. These hairs are the “eyes” of the trap. The cells lining the leaf have special digestive enzymes that can be secreted when a victim is caught. The leaf sits at the end of a stalk that puts the trap up where insects can get to it. Now, for the bait, this complex mechanism is not just a bare trap that snaps randomly or when a luckless insect falls into it. It is baited with a chemical produced by the cells that smells for all the world like rotting meat. What self-respecting fly would pass up that smell? Well, he wouldn’t and he wanders onto the trap. Now, the interesting part begins.
How exactly does this trap know when to close and how does it close? Springs, pulleys, mechanical leverage? No, the mechanism is growth! When the proper signal has been sent, the cells on the outside of the leaf begin growing at a very rapid rate. With growth on the outside, but not on the inside, the leaf, in effect, closes on itself, curling inward. The opposite would be true when the trap needs to open. The cells on the inside grow and push the trap open. But, this method of operation does put a limit to how many times the trap can be opened, as it grows too large and will die.
Well, what are the proper signals that must be sent for this trap to be closed? It goes back as I said to the trigger hairs. There are several on both sides of the trap. But, a hapless fly touching one will not close the trap. This seems to be a protective mechanism that makes sure that dust, dirt or other miscellaneous material does not close the trap. It requires that two of the trigger hairs be touched or one hair touched twice within a matter of a few seconds. This touch causes an electrical change which seems to affect hormone release which starts the growth. Once the leaf has trapped an insect, the plant will press both sides of the leaf tightly against its victim. The release of digestive enzymes then dissolves the prey. Once the insect is gone, the leaf then opens again to wait for another luckless victim.
Indeed, this is a marvelous system that has been designed should cause each of us to wonder at the miracles of the creation. The Venus Fly Trap is also an example of how hard it is to imagine a method of evolution by accidents happening over thousands and thousands of years.
