Flabellina nudibranch

Photo: Daniela Kupschus · CC BY-NC

Flabellina affinis is among the most colourful nudibranchs in the Mediterranean, its magenta cerata tipped with white and arranged in arching rows along an electric-violet body. It feeds exclusively on hydroids in the genus Eudendrium, so its presence on the Lindos wall tracks the hydroid growth cycle — populations peak from March through June and again in autumn when hydroids bloom on vertical surfaces. Females lay coiled white egg ribbons on hydroid colonies, and a careful inspection of the wall in peak season reveals multiple life stages within centimetres of each other.