2026 · Photo: Boaz Liebes
Elysia pusilla
Halimeda taco slug
Philippines · Indo Pacific - South China Sea
- Size
- 5–20 mm · max 32 mm
- Native range
- Tropical Indo-West Pacific, from East Africa and India to Japan, Australia and Hawaii.
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Description
A remarkably flattened, cryptic sacoglossan that lives only on the calcareous green alga Halimeda, matching its host so closely that it is very hard to spot. Body shape changes with the host: flat on broad-segmented Halimeda, more cylindrical on species with narrow segments. Often placed in the genus Elysiella.
Share link: https://seaslugs.org.il/species/elysia-cf-pusilla-phillipines-indo-pacific-south-china-sea/
Identification
Very flat body with reduced parapodia, shaped like a Halimeda segment. Small animals are uniform bright green; larger ones are mottled, resembling older, calcified segments.
Similar species
Other Halimeda-dwelling sacoglossans such as Bosellia species are smaller and lack the leaf-shaped flattened body; most Elysia have well-developed, upright parapodia.
Habitat & diet
Habitat
Only on Halimeda in sandy algal areas, seagrass beds and reef flats; shallow water.
Food
Feeds exclusively on the green alga Halimeda.