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I have a clam that has modified its foot to make a flat, net-like structure to catch insects often shaped like a leaf. I wanted to know where this hit in terms of feasibility or if there were any examples of an appendage like this in nature.

It lives in an extremely humid canopy that is full of water pockets and it has adapted to prolonged periods out of the water.

The muscular net would appear much like a leaf with crisscrossing portions and primary veins and would be covered in a mucus/secretion to attract and trap insects.

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    $\begingroup$ Off the top of my head a Venus Fly Trap is something along the lines of what you're describing. Given enough time, pretty much anything could evolve. You might want to consider converting this question into an Anatomically Correct Series question. Meeting those requirements would help us a lot. $\endgroup$ – JBH Jul 5 '18 at 3:45
  • $\begingroup$ I think this question could massively improved by a better description of the net. Of course it is possible, I mean you basically described hands, but since it doesn't really exist, it might be impractical. If you want to know why or when it might be impractical (or not), you need to describe it better. $\endgroup$ – Raditz_35 Jul 5 '18 at 10:04
  • $\begingroup$ Seems that this describes coral polyps pretty well, if the polyp were as mobile as a clam, as well. $\endgroup$ – Ghedipunk Jul 5 '18 at 18:03
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It is a good idea. Instead of a clam, this seemed to me like more of a snail thing to do. Snails are clam cousins so it is close. Plus snails already live on land, and your tree canopy seems like snail heaven. I went looking.

This quote is about the "pond snail" of which the Lymnaea species is one.

https://homesteady.com/info-12285231-long-life-pond-snail.html

The snail leaves an underwater slime trail, which collects plant and animal debris as well as microscopic organisms. Upon crossing its own slime path, the pond snail eats the bits and pieces stuck to the trail

Better is this great stuff on pond snail feeding I found on Google books from Behavior monographs. Cambridge, Mass. : H. Holt & Co., 1911. I love these old natural history descriptions!

All of these flesh eating snails have been seen eating dead houseflies, mayflies, fish, beefsteak and snails. They will eat such meat fresh, although they seemingly prefer it stale. I had seen them eating dead snails, when the odor from the food could scarcely be endured in the laboratory. The Lymnaea cited above have cannibal traits, a character which is especially notable in L. stagnalis. I have seen this species devouring struggling flies, moths and young snails that have become entangled in its slime…

It is a common thing to see Lymnaea stagnalis and other freshwater pulmonates turn about and eat from the foot the mass of somewhat hardened mucus together with what foreign bodies this has incorporated. Linden (1902) has observed the dexterity of Lymnaea in obtaining food from the foot, while the snail is moving upon the surface film. Brockmeier (1898) describes this process as “plankton fishing”. The mucus servers not only as a food itself but is a most efficient means of collecting food for the snail, both on solids and on the film. The trails of mucus left on solids remain sticky and serve as a trap to catch my new plants and animals and other foreign particles. The snails eat continually from the solids, devouring the mucus with all that is caught in it.

So: a mollusk which secretes sticky mucus from the foot, then eats the mucus with live prey that has stuck to it. That is what you want and that exists! A snail would probably not mind being sessile most of the time, waiting for its prey to come to it.

It is one more step to having attractive smelling mucus. I could imagine mucus that stunk could attract flies although that might attract larger carrion feeders too which would eat the snail. The same problem exists for fruit smells - fruit flies are tasty but big things like fruit. Mucus that smelled like flowers could attract pollinators - that sounds right.


I was thinking of this concept and a snail that let its viscous slime net drool down thru the air like flypaper. Then it would reel it back in with its haul of bugs.

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