Ordo Sacoglossa

Von Ihering, 1876

Shell external (univalve or bivalve), internal, or absent in the adult phase; operculum absent in post-larval stages; body-shape may be limaciform, aeolidiform (with dorso-lateral cerata), or flattened and leaf-like; if cerata are present, they lack cnidosacs; head bearing digitiform, auriform, or inrolled rhinophoral tentacles (occasionally absent); oral tentacles very small or absent; mantle cavity and gill usually lacking; foot elongated, usually closely united with the head and visceral mass; gizzard plates lacking; potash-resistant jaws absent; radula narrow, uniseriate; abraded or broken teeth are not always discarded from the radula ribbon, and many or all of the worn teeth may be retained in a special sac (the ascus); pharynx often with a muscular buccal pump; digestive gland often much-branched, with tributaries in the head, tentacles, foot, and cerata (where present); hermaphrodite reproductive system lacking an external seminal groove in the British forms; penis often armed with a stout stylet; impregnation occasionally hypodermic; central nervous system euthyneurous, forming a ganglionic ring around the foregut, behind the buccal mass. In habit, most sacoglossans are herbivores, feeding principally (but not exclusively) upon green algae.

Source: Thompson, 1988.

The following subtaxa of this order occur in the region:

Subfamily Polybranchiinae
Family Stiligeridae
Genus Alderia
Alderia modesta
Genus Calliopaea
Calliopaea bellula
Family Elysiidae
Genus Elysia
Elysia viridis
Genus Hermaea
Hermaea bifida
Genus Limapontia
Limapontia capitata
Limapontia depressa
Limapontia senestra
Family Polybranchiidae
Genus Placida
Placida dendritica