Aplysia chemical defense

Aplysia with chemical defenses in their tissues but without ink were consumed at a similar rate to those without toxins (20% vs. 12%), whereas those without toxins in their tissues, but with ink exhibited much greater survival (71%), suggesting that the excretion of ink may be the primary defense of these sea hares when being consumed by slow-moving predators like sea anemones.45 Pennings42 also found that ink from some (but not all) sea hares could deter predators, however he found no evidence that the metabolites responsible for defense were diet derived. Sea hares also secrete opaline when attacked by predators, although the function of this secretion has yet to be unambiguously determined.44... 

Ginsburg, D. W. and Paul, V. J., Chemical defenses in the sea hare Aplysia parvula importance of diet and sequestration of algal secondary metabolites, Mar. Ecol. Prog. Ser., in press. 

An investigation of the the chemical defense of Aplysia fasciata collected from the Bay of Naples has resulted in the identification of 4-acetylaplykurodin B[24] and aplykurodinine B [25] (38). 

Johnson PM, Kicklighter CE, Schmidt M, Kamio M, Yang HC, Elkin D, Michel WC, Tai PC, Derby CD (2006) Packaging of chemicals in the defensive secretory glands of the sea hare Aplysia califomica. J Exp Biol 209 78-88... 

Sea hares and nudibranchs feed on seaweeds to acquire their chemicals for defense. The common sea hare Aplysia dactylomela from Spain contains puerti-tol-B acetate (333) (554), whereas this animal collected off the coast of South Africa affords the new algoane (334), 1-deacetoxyalgoane (335), l-deacetoxy-8-deoxyalgoane (336), and ibhayinol (337) (555, 556). Investigation of this sea hare from La Palma has uncovered the new 338 along with two other halogenated compounds shown in section Eudesmane and Other Types (557). 

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