David Fleetham / Imperial commensal shrimp (Periclimenes imperator / Zenopontonia rex) on Spanish dancer nudibranch (Hexabranchus sanguineus) at night. Philippines.

Alex Mustard / Detail of rhinopores and the colour pattern of a toxic Nudibranch (Goniobranchus coi) on a coral reef. Ambon Bay, Ambon, Maluku Archipelago, Indonesia. Banda Sea, tropical west Pacific Ocean.

Alex Mustard / Nudibranch (Goniobranchus hintuanensis) portrait showing rhinophores. Anilao, Batangas, Luzon, Philippines. Verde Island Passages, Tropical West Pacific Ocean.

Alex Mustard / Close up detail of the rhinophores and caruncle of a Nudibranch (Janolus savinkini). Anilao, Batangas, Luzon, Philippines. Verde Island Passages, Tropical West Pacific Ocean.

Alex Mustard / Nudibranch (Ceratosoma trilobatum) detail of chemo-sensory rhinophore, Anilao, Batangas, Luzon, Philippines. Verde Island Passages, Pacific Ocean.

Alex Mustard / Detail of the sensory rhinophore of an Orange peel nudibranch (Tochuina tetraquetra). Browning Pass, Vancouver Island, British Columbia, Canada. North East Pacific Ocean.

Juergen Freund / Close up of rhinophore of Nudibranch (Halgerda sp) from Discodorididae family

David Fleetham / Close up of rhinophores of Scrambled egg nudibranch (Phyllidia varicosa), Hawaii, Pacific Ocean.