The Effect of Algal Diet on Ink Production in the Spotted Sea Hare (Aplysia dactylomela).

Spotted Sea Hares (Aplysia dactylomela) are slow moving, herbivorous opisthobranchs common to Discovery Bay, Jamaica. As a defensive mechanism, they are able to release a vivid purple ink which can disorient potential predators. In our study, we looked at the effect of three algal types – green, red, and brown – on the Sea Hares’ ability to produce ink. To determine this, four groups of eight Sea Hares each were isolated and each group fed a strictly monitored diet. One group with only green algae (Derbesia sp.), one group with only red algae (Jania adherens, Coelothrix irregularis, and Gracilaria cervicornis), one group with only brown algae (Dictyota divaricota), and a fourth control group which was fed all types. Each day, we gently handled the Sea Hares over a container to collect the ink and measured it with a syringe. Our results show that the Sea Hares which were fed red algae were the only ones that could still produce a substantial amount of ink after seven days of testing. The implications of this are that if red algae were to be outcompeted by green or brown algae, the Sea Hares may lose their defensive inking ability, potentially leading to more successful predation upon them and, eventually, their disappearance from the area.

– Megan and Kathleen