The colourful world of Nudibranch

These small and beautiful creatures are ever more becoming popular in the world of snorkeling. Over the past few years it’s great to see more macro species, becoming a must see on our snorkeling trips. With Nudis ( Nudibranch ) being at the top of the list. With so many variations of colour, size and shape they are a spectacle for the eyes. The best part of this, is we can find them on almost all our tours. Top tip for finding nudis. Stay close to the local guides. They have eagle eyes for these things.

Nudibranchs are a type of sea slug, and there are over 3000 species found from across the globe in both shallow and deep water. Though they often only reach a small size, they are famous for their spectacular colour and patterns. Nudibranchs get their name from the Greek (nudi) and latin (branch) words meaning “naked gills”. There are two main types of nudibranchs: dorid nudibranchs look fairly smooth, with a tuft of feather-like gills toward the back of the animal that are used to breathe. Aeolid nudibranchs instead breathe with organs called cerata covering their backs. Nudi

Nudis are hermaphroditic, having a set of reproductive organs for both sexes, but they cannot reproduce by themselves. Mating involves a dance-like courtship. Nudibranchs typically lay their eggs in spiral formation, which is often described as looking like a ribbon or even a rose flower. The number of eggs varies, it can be as little as just 1 or 2 eggs, or as many as 25 million. The eggs can contain toxins from sea sponges as a means of warding off predators. After hatching, the infants look almost identical to their parents, though smaller. The lifespan of nudibranchs can range from a few weeks to a year, depending on the species.


All known nudibranchs are carnivorous. Some feed on sponges, others on hydroids and some eat other sea slugs or their eggs. Nudis are also known to be cannibals and prey on members of their own species. Nudibranchs that feed on hydrozoids can store the hydrozoids’  (stinging cells) in the body. These stolen nematocyst remain,  throughout the body without harming the nudibranch. Providing them with a layer of protection. Having all these bright and beautiful colours lets other predators know they are not to be eaten and can be toxic. Nudi

We love finding them, not only to observe, but for photography to make a great subject. Not to mention a beautiful colourful photo. As I mentioned before these weird and wonderful critters can be found on nearly all our Snorkel Venture tours. With the house reefs in Alor, Raja Ampat, Komodo and Sulawesi being top Nudi spotting areas. Our best chances to find them are in the shallow reefs or where we go for designated “Muck snorkeling”. The trick to finding them is to go slowly across the reef or sandy patches taking your time. Though extremely colourful they are not the easiest things to find. My other top tip for finding them is to stay close to the local guides. They are by far the best at finding them. That being said it is very exciting and a great sense of achievement when you find your first. Happy hunting.Nudi

About Author

Marcus Blake
Marcus joined the Snorkel Venture team in 2021. Prior to that for five years was managing dive and snorkel operations at Komodo Resort in Indonesia. He has been fortunate enough to have worked and travelled to some of the best snorkel locations in the world. Giving him a wealth of experience and knowledge of the oceans.