Costasiellid sap-sucking slugs

Costasiellidae

Species in the gallery: 2
Genera: 1

Description

Costasiellidae is a family of sacoglossan sea slugs (Sacoglossa), currently accepted in WoRMS with the genera Costasiella and Panderevela; some classifications place Costasiella within Limapontiidae. Species are tiny, usually under 1 cm, and occur in tropical and warm-temperate seas, especially the Indo-West Pacific and Caribbean. They feed on green algae, mainly Avrainvillea, piercing cells and sucking out the contents. Some species keep functional chloroplasts from their food; Costasiella kuroshimae, the 'leaf sheep', is a popular macro subject.

Identification

Tiny, soft slugs with many inflated, leaf- or spindle-shaped cerata crowded over the back, often green with white, blue or yellow tips. The eyes sit close together on top of the head between two smooth, rolled rhinophores, giving a 'face'. They are usually found on Avrainvillea; the close-set eyes help separate them from similar Limapontiidae such as Ercolania.