The trap

The traps of Aldrovanda vesiculosa look like small (1/12 inch), translucent flytraps appearing at the end of a broad petiole. Surrounding the trap are hair-like bristles that prevent the traps from bumping against other aquatic plants and getting damaged or falsely triggered. The outer edges of the trap lobes are lined with many hook-like teeth (analogous to the flytrap’s teeth) that interlock when the trap closes around prey. Within the trap you’ll find around forty long trigger hairs (imagine the 6-to-8 trigger hairs inside a Venus flytrap trap) that, when stimulated one-or-more times, cause the clam shell trap to snap shut. Alongside the trigger hairs, there are digestive glands that secret acids used to break down a prey’s soft tissues for absorption.

Traps seal around unfortunate prey using a combination of the interlocking teeth and mucus sealant, forcing it to the base of the trap, nearest the hinge. At this point, the trap forces out much of the water and replaces it with the digestive juices. Like a flytrap trap, each Aldrovanda trap can catch 2-4 meals before calling it quits.

Unlike Venus flytraps, there’s no known lure to attract insects to the traps.