Aplysia Ink and Opaline: Exploration of their Relation to Predation

The release of ink by sea hares (Aplysia spp.) is generally considered a defense mechanism, although there are little data indicating the predator-prey relationships of these animals. The possibility that Aplysia brasiliana could be prey for crabs, eels and anemones in the waters off the coast of Puerto Rico was examined by presenting adult sea hares (live and dead) to six blue crabs (Callinectes sapidus); subsequent to those presentations, fish, a common prey, were made available to the crabs. All crabs ate the fish. In no case did crabs eat live or dead sea hares, and in no case did the sea hares release ink or opaline, although three crabs made contact with the live sea hares. Two species of anemones, Phymanthus crucifer and Aiptasia tagetes. were presented with small sea hares (3–5 cm). The former ingested one out of 14 sea hares, while the latter ingested 4 out of 4 sea hares. In no case was the presence of ink a factor in the “escape” of the sea hare or its ingestion by anemones. These exploratory observations indicate that it may be necessary to investigate other adaptive processes in which the inking mechanism could be involved.