Nudibranch Behaviors in the Lembeh Strait

Hypselodoris bullockii laying eggs

Nudibranch laying egg mass

  I have seen nudibranchs in cold California kelp forest, on deep wall dives, in tide pools, and on rubble bottom tropical muck dives. Their vivid colors make them fit right into their surroundings in Indonesia, especially with all of the vibrantly colored soft corals, sponges, and hydroids covering the shallows. But in all of these different habitats certain behaviors remain the same. Egg cases will be attached to sturdy rocks or coral, mating will also be right side to right side, and nudibranchs will find poisonous stationary creatures like hydroids to feast upon and in turn use those toxins as part of their own defense.

Nudibranch searching for food

Nembrotha rutilans feeding

Risbecia tryoni nudibranchs mating

  We found so many nudibranchs during our week diving the Lembeh Strait that we were lucky enough to see and photograph most of the different behaviors these creatures display. The big find was a pale purple  Hypselodoris bullockii laying a yellow egg mass on the reef. We often come across nudibranch eggs that have recently been layed, but to get to see it in action is a rare treat indeed. We found several species feeding as well as mating nudibranchs. In the mating pictures you can see the connection between the nudibranchs.

Nembrotha rutilans mating. Nudibranchs are hermaphroditic but cannot fertilize themselves.