Sea Slugs

5 Fun Facts About Nudibranchs

Have you ever seen a Nudibranch when you went diving


Nudibranchs are a group of soft-bodied, marine gastropod molluscs. Some are known for their extraordinary colours and striking forms, and they have been given fun nicknames to match, such as "sea goddess", "splendid", “dragon", “painted” or ‘dancer” just to name a few. Currently, about 3,000 valid species of nudibranchs are known. Many gastropods have a shell. Nudibranchs have a shell in their larval stage, but it disappears in the adult form.

Here are 5 fun facts about “Nudis” to get you all excited to spot one on your next dive!

  1. Nudibranchs lose their vestigial shell during a larval phase.  To protect themselves they rely on toxins or unpleasant tasting chemicals which are advertised with extremely vivid colors.


2. A pair of tentacles called rhinophores on the nudibranch's head have scent receptors that allow the nudibranch to smell its food or other nudibranchs. Because the rhinophores stick out and can be a target for hungry fish, most nudibranchs have the ability to withdraw the rhinophores and hide them in a pocket in their skin if the nudibranch senses danger.


3. Nudibranchs are hermaphrodites. Because they move very slowly they need to be ready for reproduction whenever they meet another nudibranch – no matter if it is female or male. This makes reproduction process very convenient for Nudibranchs.


4. There are certain species of Sap-sucking slugs (or sacoglossans) that produce solar power by eating corals which are rich in algae. Nudibranchs absorb the chloroplast of the algae and engage in photosynthesis. The created nutrients help Nudibranchs to survive and obtain the established energy for several months.


5. Most Nudibranchs eat using a radula, a toothed structure that can be compared to the tongue they use it to scrape off their meal from the rocks they cling to; some suck out the prey after predigesting its tissue with selected enzymes. They are carnivorous, so their prey includes sponges, coral, anemones, hydroids, barnacles, fish eggs, sea slugs, and other nudibranchs. Nudibranchs are picky eaters—individual species or families of nudibranchs may eat only one kind of prey. Nudibranchs get their bright colors from the food they eat. These colors may be used for camouflage or to warn predators of the poison that lies within.