One of the most common polyp animals are the branch tongues, which is a bit of a misnomer since not all of them have branched tongues. Some have multiple ends per tongue, some have multiple tongues per mouth, some have multiple mouths per stomach, some have multiple stomachs per body, and some are colonial organisms of multiple bodies. Many have some combination of all these attributes. At the ends of the tongues are sticky lures to attract different types of swimming prey or sticky hairs to grab floating plankton. Snap traps have yet a different sort of lure. They resemble nooses. The lures of snap traps are not sticky, but will snap shut on anything disturbing the lure in the middle held only by two narrow strings. Once a meal has been caught, the tongue is pulled down into the stomach (where its base is attached) to be digested along with the meal. For those species with more than one tongue end per stomach, the animal will usually wait until seventy percent or more of its tongue ends are full before drawing them all in. It cannot wait too long, however, because there are other animals that might crawl by and try to steal a meal.
The pin traps are one family of branch tongues that take advantage of this. The lures are able to sense what type of prey has bitten into them. When bitten by small prey, the lures merely swell up and secrete glue to hold it there, using the small prey as a lure for larger prey. When bitten or grabbed by large prey, a large number of mineral fibers from deep in the tongue shoot outwards at high velocity, hardening on contact with foreign tissue and sending out offshoots to hold them in place. On signal, the animal will draw its other tongue ends around whatever it has caught, all of them extruding rapidly hardening mineral fibers on contact. It then pulls the prey into its mouth.
Written by Daniel Noe, ChampionOfTheUniverse.com