Fig. 4.

Small herbivores that deter enemies using toxic hosts. A) The sea slug Costasiella ocellifera eats only the green alga Avrainvillea longicaulis, sequesters the compound shown, and is therefore rejected by fish predators. B) A similar interaction for the sea slug Elysia sp. It consumes Caulerpa sp., sequesters and converts its compound for storage and protection of itself and its eggs (the yellow mass on the alga). C) The amphipod Pseudamphithoides incurvaria creates a domicile from its algal host (Dictyota). Pachydictyol-A cues this behavior and deters fishes from consuming the amphipod. The drawing shows the amphipod more clearly. D) The crab Caphyra rotundifrons lives in and consumes only the green alga Chlorodesmis fastigiata, which is protected from herbivorous fishes by the cytotoxic compound chlorodesmin. Chlorodesmin, deters fish feeding but stimulates feeding by the crab. E) The crab Libinia dubia decorates with the chemically-defended alga Dictyota. Dictyot-E from the alga cues decoration and deters fishes from consuming the crab.