In neurons that mediate several forms of long-term memory in Aplysia, the DNA repair enzyme poly ADP ribose polymerase 1 (PARP-1) is activated.

[3] Cohen-Aromon et al.[3] suggested that fast and transient decondensation of chromatin structure by polyADP-ribosylation enables the transcription needed to form long-term memory without strand-breaks in DNA.

[4] In 2018, scientists from the University of California, Los Angeles, have shown that the behavioral modifications characteristic of a form of nonassociative long-term memory in Aplysia can be transferred by RNA.

Because operant conditioning involves intricate interaction between an action and a stimulus (in this case food) it is closely associated with the acquisition of compulsive behavior.

The properties of the synapses displayed in the tests on conditioning involving the Aplysia (which has dopamine neurons but not a ventral tegmental area) are proposed to be directly comparable to behavioral responses such as addiction in mammals.

[9] Aplysia are simultaneous hermaphrodites, meaning each adult individual sea hare possesses both male and female reproductive structures that may be mature at the same time.

Instead, recent research has made it clear that these sea slugs are able to produce and secrete multiple compounds within their ink, including the chemodeterrant Aplysioviolin and toxic substances such as ammonia for self-defense.

When the sea hare feels threatened it immediately begins the process of defending itself by mixing the distinct molecules in an additional part of the body used specifically for that purpose.

At which point, enzymes within the sea slug begin the process of making the substance toxic, and the mixture is ejected out at the predator in self-defense.