Let’s talk about nudibranchs.
I think sometimes these beautiful creatures are under-appreciated by people. More often than not, I hear divers saying they want to see the big stuff, the mantas, whale sharks and great barracudas. I always ask students the question on their first open water dive, “what would you like to see on this dive?” and almost never would I get a nudibranch as a reply.
As much as I understand that non divers would hardly come across or know about our friendly sea slug, I wish our little friend would be given more recognition for its physical beauty, its role in the ecosystem and for its rather amazing traits.
For starters, the name Nudibranch actually means ‘naked gill’. This separates them from other sea slugs. You know the ‘furry’ thing on top of their bottoms? Yep, those are its ‘naked gills’. Whenever I encounter them while diving, I always think to myself, they seem so fragile, conspicuous and weak. Why aren’t they picked off by predators like the oyster section of a buffet line?
Turns out, they have given u the hard protection of a shell for something quite effective as well- toxic secretions and stinging cells. A few make their own poisons, but most pilfer from the foods they eat. For example, some species dine on toxic sponges and fire corals and store the stinging compounds on their bodies and secrete them when disturbed.
Their bright pigments also serve as a defence by deterring predators. They contrast greatly against the reef’s greens and browns and some other animals (i.e. flatworms) also benefit by mimicking their patterns with the hope of being left alone by predators.
If you’re wondering what their cute ‘horns’ are on the top of their heads? Well, nudibranch have very bad vision. They smell, taste, and feel the world using head-mounted sensory appendages called rhinophores and oral tentacles.
What is amazing is that there are over 3,000 species of nudibranchs and scientists believe that we have discovered only half of all species. It is sad that these brilliant creatures have short lifespans. Most only live up to a year before disappearing without a trace.
As a tribute to our sea slug friends, we’ll be posting some cool facts you probably never knew about nudibranchs on our Facebook page. We hope you meet plenty of them when dive season opens!
Till then, dive safe always.