Nudibranchs in Lembongan
Lembongan is very famous for its larger creatures, but when you take the time to look, you may find some crazy little creatures too. Nudibranchs can be found at all the dive sites around Lembongan and Penida. These small ‘slug’ creatures are very much a favorite creature to many divers.
Colourful Creatures to spot:
Nudibranchs are noted for their often extraordinary colours and striking forms. Currently there are about 2,300 valid species of them that are known. With this, it is possible to buy fish ID books that have 100s of pages full of these colourful creatures.
The word “nudibranch” comes from the Latin word, nudus, meaning naked, and the Greek word, brankhia, meaning gills. Like all fish, they have gills which they use to process the oxygen in the water, allowing them to breath. As the name suggests, their gills are on the outside of their body. The ‘flowery’ part that is found on the back of the nudibranch, is in fact their gills.
The little ‘antenna’ on top of the nudibranch’s head are called Rhinophore. These are used as the nudibranch’s nose and one of their main senses for getting around.
Nudibranchs can be some of the most colourful creatures on earth. Over the course of their evolution, they have lost their shell while developing alternative defense mechanisms. Some Nudibranchs have an external anatomy with textures and colours that mimicked surrounding, allowing it to be camouflaged.
Other nudibranchs feed on hydrozoids (stinging cells) and can store these hydrozoids’ in their dorsal body wall. These will then effect the prey that tries to feed on them.
Nudibranchs are hermaphroditic, thus have a set of reproductive organs for both sexes, but they cannot fertilize themselves. The genital apparatus is on the right hand side of their body. Two nudibranchs can come together, one faces one way and one faces the other way, with the right hand side of their bodies touching. The penis from one fits into the female opening of the other one, and the penis from that one fits into the female opening of the first one.They are both donating sperm to the other one. After, each of them walk away fertilized.
There is also a type of nudibranch that, after mating, is able to drop its penis and regrow it. With in just 24-hours, it can regenerated it’s male organs and is able to mate again.
Nudibranchs normally lay their eggs in an egg spiral. The size and colour of the spiral can represent which type of nudibranch it came from.
All known nudibranchs are carnivorous. Most feed on sponges, or hydroids, some feed on other nudibranchs and their eggs. There are also some that feed on anemones and jelly fish.