Nudibranch in Lembeh

What’s better than finding a nudi on your dive? Finding two nudis together on your dive! Happy Valentine’s day to all from Lembeh Strait, where romance is also happening underwater…
Nudibranch in Lembeh are a particular favourite of ours which is why a nudi couple (Hypselodoris bullockii) has made the featured photo. Nudibranch in Lembeh are often found in mating pairs; since all nudibranchs have both male and female genitalia on their right side they conduct a straight swap! To mate they line up head to tail with the right side of the body touching and once they’re finished each slug will leave to lay it’s own cluster of eggs in a tightly woven ribbon. That is, if their partner doesn’t eat them during the act (yes nudibranchs are often cannibalistic)!

Different slugs exhibit different mating behavior with some staying connected for hours and others rarely seen together. Some headshield slugs, such as Chelidonura variens, show elaborate courtship behavior and will circle one closely before the act. Even stranger than the slugs are the flatworms! Flatworms are hermaphroditic and they engage in ‘penis-fencing’ where they will fight over who will inseminate who. Some penises have a hooked end and the fight ends when one wounds the other. The sperm then enters through the body wound. Not all species fight like this, some exchange sperm directly with one another.

Mating behavior is always fascinating to watch underwater when it comes to nudibranch in Lembeh but they are not the only ones! We have a special dusk dive to see the beautiful mating ritual of the mandarinfish and we are always on the lookout for tiny juveniles and eggs of various species! What better way to celebrate romance than to go for a dive with your favourite dive buddy!

Do you want to come and see the nudibranch in Lembeh with us? Or some of our weird and unusual critters?

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