| Scientific name | Pteraeolidia ianthina |
| English name | Pteraeolidia ianthina |
| Japanese name | --- |
| Class | Gastropoda |
| Order | Nudibranchia |
| Family | Facelinidae |
| Genus | Pteraeolidia |
| Species | ianthina |
| Subspecies | --- |
| Full length | 5-10cm |
| Distribution | Distributed along the Pacific coast of Honshu. |
A sea slug with distinctive bluish-purple projections. The body is slender and sometimes coiled. The head is cream colored and the antennae are dark purple. Body color varies from individual to individual.
It inhabits rocky reefs in shallow water, where seaweed and rock surfaces are easily visible. It preys on cnidarians such as hydroids.
It moves like crawling between seaweed and coral.
This photo was taken in shallow water on a rocky beach in August. When there was one, there were many attached to the same rock. It had an elongated silhouette, and some were curled up.
Introducing a picture of Pteraeolidia ianthina.