Hydroid colonies, that appear to be relatives of sea anemones and corals, serve Nudibranchia for board and lodging.
Entangled laces of egg ribbons (white on the picture) are laid and develop on the hydroid's twigs. Aeolidina plumed sea slugs (both Flabellina affinis and a pair of Cratena peregrina at the picture) do not digest the stinging cells called nematocyst when feeding on Cnidaria tentacles, but pass them through the liver appendices located in processes upon their backs called ceratae to the special cnidosac bladders, where the stinging cells are accumulated.
Entangled laces of egg ribbons (white on the picture) are laid and develop on the hydroid's twigs. Aeolidina plumed sea slugs (both Flabellina affinis and a pair of Cratena peregrina at the picture) do not digest the stinging cells called nematocyst when feeding on Cnidaria tentacles, but pass them through the liver appendices located in processes upon their backs called ceratae to the special cnidosac bladders, where the stinging cells are accumulated.
