An anti-predator chemical defense of the marine pulmonate gastropod Trimusculus reticulatus (Sowerby)

Anti-predator defenses of the marine pulmonate gastropod Trimusculus reticulatus (Sowerby) were studied in the laboratory. By repeatedly presenting the seastars Pisaster ochraceus (Brandt) and P. giganteus (Stimpson) with one Trimusculus reticulatus and an individual of some species of prosobranch limpet, it was shown that seastars tended to avoid eating T. reticulatus (P < 0.001). When attacked, T. reticulatus secretes a milky-white mucus. After this mucus was spread on the shells of prosobranch limpets, those limpets were eaten by Pisaster significantly less often than clean limpets of the same species (P < 0.001). This defensive mucus contains a compound which temporarily stuns the tube feet of an attacking seastar. Seastars suffered no lasting effects from repeated exposure to this defensive mucus, and those which ate Trimusculus reticulatus showed no ill effects. Feeding preference experiments with the crab Pachygrapsus crassipes (Randall) indicated that the mucous defense of Trimusculus reticulatus is not effective against this predator.