Description: The two Aeolidia species are the largest aeolids in the British Isles. A. papillosa is usually grey in overall appearance due to freckles of grey or brown pigment, but the colour is very variable. The head is freckled with darker pigment. The oral tentacles and rhinophores are tapering with thick bases. The cerata are rounded in cross section.

Habitat: Aeolidia papillosa feeds on sea anemones, mostly in the sublittoral. The normal prey is Metridium senile and Actinothoe sphyrodeta. The spawn is distinctive, consisting of a thread coiled back and forth and laid in a spiral.

Distribution: This is a widespread animal, commoner in the north of the British Isles and around Northern Europe.

Similar Species: Distinguished from Aeolidia filomenae by the absence of a white Y-shaped mark on the head.

Key Identification Features:

• Large aeolid with superficial pigment over body and cerata.
• Has freckled pigment on the front of the head.

Distribution Map from NBN: Aeolidia papillosa at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Aeolidia papillosa at iNaturalist World Species Observations database.

WoRMS: Aeolidia papillosa at World Register of Marine Species. Accepted name: Aeolidia papillosa (Linnaeus, 1761). AphiaID: 138709.

Classification: Biota; Animalia; Mollusca; Gastropoda; Heterobranchia; Euthyneura; Ringipleura; Nudipleura; Nudibranchia; Cladobranchia; Aeolidioidea; Aeolidiidae; Aeolidia