2026 · Photo: Boaz Liebes
Costasiella kuroshimae
Leaf sheep
Philippines · Indo Pacific - South China Sea
- Size
- 3–5 mm
- Depth
- 5–15 m
- Native range
- Western Pacific: Japan, the Philippines and Indonesia
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Description
The famous 'leaf sheep', a tiny sacoglossan named for its sheep-like face and leaf-shaped cerata. It retains functional chloroplasts from the algae it eats (kleptoplasty). Molecular work shows that several undescribed cryptic species look almost identical externally.
Share link: https://seaslugs.org.il/species/costasiella-kuroshimae-phillipines-indo-pacific-south-china-sea/
Identification
Only 3–5 mm. Head white with a dark mark between and behind the eyes; large eyes set close together. Rhinophores white with black tips. Cerata in about seven rows, green with white tips and scattered iridescent dots.
Similar species
Costasiella usagi has black rhinophores and black outer cerata. Several undescribed Costasiella look almost identical and cannot be reliably separated in photos.
Habitat & diet
Habitat
On the green alga Avrainvillea on shallow reefs and sandy slopes, around 5–15 m.
Food
Sucks the green alga Avrainvillea (e.g. A. lacerata), keeping its chloroplasts.