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Species of the Month: Nudibranchs!

One of the Master Divers team’s favourite underwater creature is the Nudibranch; part of the sea slug family these shell-less mollusks come in all different shapes, sizes and colours. They can be as small as 6mm and as large as 31cm, they are found all over the world but they are most common in shallow, tropical waters.


For us as Divemasters and Instructors it’s always great fun spotting one of these critters, the smaller and stranger the better! Some of us see it as a challenge and if you know you are diving with Nudibranch enthusiasts it can be a great way to add a bit of competition into a dive by seeing who can find the smallest or wackiest one!

Nudibranch are also a favourite among photographers, especially those into Macro photograph, as their vivid colours and variety of shapes really make for fantastic pictures! They are the perfect slow moving models and can often be found clinging to the coral in picturesque areas giving photographers plenty of time to capture their beauty on camera.





Here are some Nudi facts for you that you may not have known:

  • Their scientific name, Nudibranchia, means naked gills, and describes the feathery gills and horns that most have on their backs.
  • Nudibranchs are actually carnivorous creatures, they diet on anything from algae, sponges and anemones and even other Nudibranchs!
  • They protect themselves from predators by ingesting toxins from the food they eat and then secrete the poisons through their outer layers if disturbed or if they sense danger!


  • Nudibranchs are simultaneous hermaphrodites, and can mate with any other mature member of their species.
  • Their lifespan varies widely, with some living less than a month, and others living up to one year.
  • These guys thrive in any condition; from shallow sandy tropical waters to dark murky depth of the oceans!




Nudibranch can be found at nearly all of our dive sites here on Koh Tao, with the most common species being the Varicose Wart Slug, and the bunny rabbit lookalike Jorunna Funebris. Keep your eyes open on your next dive and see which nudi you can spot!

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