Wednesday, 12 October 2011

Maybe the glue is appropriate...

How does a stationary organism manage to attract, kill, digest and absorb its prey? First, it lures its victim with sweet-smelling nectar, secreted on its steel-trap-shaped leaves. Unsuspecting prey land on the leaf in search of a reward but instead trip the bristly trigger hairs on the leaf and find themselves imprisoned behind the interlocking teeth of the leaf edges. There are between three and six trigger hairs on the surface of each leaf. If the same hair is touched twice or if two hairs are touched within a 20-second interval, the cells on the outer surface of the leaf expand rapidly, and the trap snaps shut instantly. If insect secretions, such as uric acid, stimulate the trap, it will clamp down further on the prey and form an airtight seal. (If tripped by a curious spectator or a falling dead twig, the trap will reopen within a day or so.) Once the trap closes, the digestive glands that line the interior edge of the leaf secrete fluids that dissolve the soft parts of the prey, kill bacteria and fungi, and break down the insect with enzymes to extract the essential nutrients. These nutrients are absorbed into the leaf, and five to 12 days following capture, the trap will reopen to release the leftover exoskeleton. After three to five meals, the trap will no longer capture prey but will spend another two to three months simply photosynthesizing before it drops off the plant. Plant owners should beware of overstimulating a Venus flytrap: after approximately 10 unsuccessful trap closures, the leaf will cease to respond to touch and will serve only as a photosynthetic organ.
Scientific American

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