In Aplysia and Syphonota, this shell is a soft flattened plate over the visceral rear end, where it is fully or partially enclosed in the mantle skin.

The shell is only present in the larval stage of the two genera Bursatella and Stylocheilus, and on this basis they have been grouped into the subfamily Dolabriferinae.

They are cosmopolitan and found in temperate and tropical seas, inhabiting shallow coastal areas and sheltered bays, thick with vegetation.

Some species spout ink when disturbed or attacked, and they may also swim (rather than crawl) away, using their broad wing-like flaps or parapodia.

The genus Aplysia has proved useful as a model in neurobiology for the study of electrical synapses, which mediate the release of the clouds of ink.

The penis is on the right side of the head while the vagina is situated in the mantle cavity, beneath the shell, deep down between the parapodia.

[9] A 2004 study[10] has shown that Aplysiidae is a monophyletic taxon with two distinct clades: Aplysiinae and Dolabellinae + Dolabriferinae + Notarchinae.