Meeting Abstract
Relatively little is known about the interactions between sacoglossan sea slugs and potential predators. Placida kingstoni is a small sacoglossan that conducts ceratal autotomy, deliberately casting off body structures due to danger or stress. Although the ability of some sacoglossan species to conduct autotomy has been reported, very few studies have assessed its effectiveness as a defense mechanism against predation. The purpose of this investigation was to evaluate P. kingstoni’s autotomy in the presence of a potential predator and the effect that autotomy has on survival. The caridean shrimp Lysmata wurdemanni was selected as a potential predator due to its habitat overlap with P. kingstoni, generalist diet, and aggressive behavior. Each shrimp was individually isolated, underwent a period of starvation, and was then exposed to a sea slug for a ten-minute observation. In most interactions P. kingstoni was attacked by L. wurdemanni, suggesting that the slug is palatable and that the shrimp is in fact a plausible predator of the sea slug. Although they were attacked, and some slugs were eaten, most slugs autotomized cerata and survived the encounter. L. wurdemanni often directed its attention to the autotomized cerata clusters and consumed them, which allowed the slugs to survive. This demonstrates that in P. kingostoni ceratal autotomy can be an effective defense mechanism against certain predators. However, autotomy might not be effective against other organisms that exhibit different modes of attack, requiring slugs to use other defenses such as crypsis or chemical secretions. Although autotomy increased survival in P. kingstoni, its effectiveness for other sacoglossans is still mostly unresolved.
