Alex Mustard,Alex Mustard / A nudibranch (Dendronotus frondosus) photographed in the field aquarium, Gulen, Norway. North East Atlantic.

Wild Wonders of Europe / Lundgren / Nudibranch (Dendronotus frondosus) on a Kelp leaf, Moere coastline, Norway, February 2009

Fred Bavendam / Giant Nudibranch (Dendronotus iris) attacking a Tube-dwelling Anemone (Pachycerianthus fimbriatus), Vancouver Island, British Columbia, Canada. Sequence 4 of 5

Franco Banfi / Robust frond-aeolis (Dendronotus robustus) nudibranch on Kelp. Tasiilaq, East Greenland. April.

Olga Kamenskaya / Frond eolis (Dendronotus frondosus) Novaya Zemlya, Russian Arctic, July

Sue Daly / Nudibranch (Dendronotus frondosus) Isle of Man, July.

Franco Banfi / Giant dendronotid nudibranch (Dendronotus iris) Vancouver Island, British Columbia, Canada, Pacific Ocean

Franco Banfi / Giant nudibranch (Dendronotus iris) Vancouver Island, British Columbia, Canada, Pacific Ocean

Fred Bavendam / Giant Nudibranch (Dendronotus iris) attacking a Tube-dwelling Anemone (Pachycerianthus fimbriatus), Vancouver Island, British Columbia, Canada

Alex Mustard / A nudibranch (Dendronotus frondosus) photographed in an aquarium, Gulen, Norway. North East Atlantic.

Franco Banfi / Nudibranch (Dendronotus frondosus) Arctic circle Dive Center, White Sea, Karelia, northern Russia

Jeff Rotman / Giant Dendronotid Nudibranch (Dendronotus iris) swimming at night, Vancouver Island, British Columbia, Canada, North Pacific Ocean