Bali is well known by divers and underwater photographers for its manta rays, oceanic sunfish, and other large marine creatures. These are some of the most majestic animals to dive with and photograph but macro enthusiasts know that there is something really special hidden in the sandy muck at the bottom of the ocean as well. Nudibranchs are a type of sea slug, which doesn’t sound very glamorous, but they are actually arguably the most varied and colourful creatures in the sea. Let’s learn a little bit about these amazing animals.

What in the world is a nudibranch?

Strange creature with a strange name, but in fact the name comes from the Latin nudus meaning naked and the Ancient Greek bránkhia meaning gills. They are often referred to as nudis or even sea slugs as they are in the opistobranch family.

The range of colours, shapes, and sizes of nudibranchs is almost endless. There are currently about 3000 species known and more being discovered all the time. They range in size from a miniscule 4mm to a much more significant 600mm. This is a massive range so for the smaller species it can be a real challenge to spot.

It is the sheer variety and showiness of their appearance that makes them so attractive to macro photographers. Once you’ve captured a great nudibranch photo, you will want to find more and more to shoot.

Where can I find nudis?

Nudis are found all over the world at depths varying from the foreshore to up to 700m down. With only two known exceptions, they inhabit the substrate at the bottom of the water. Muck diving is the best way to find nudibranchs, and luckily some of the best muck diving in Bali is around the Candidasa area.

Padang Bai’s Amuk Bay is a favorite muck diving spot and plenty of nudibranchs are found on dives here. It’s also a great beginner dive so if you are new to diving it may be that you get to search for nudis early on. Some other sites you are likely to see nudibranchs are Amed, Salayar, Tulamben, the Liberty Wreck, and Gilimanuk.

Some strange and interesting facts about nudibranchs:

• The majority of nudibranchs move across the sea floor just like a snail but some can swim short distances by moving their muscles sort of like fins
• Some nudibranchs are poisonous. Without shells they are a tasty snack for many marine creatures but poison keeps them safe.
• There are some species of nudibranchs that can do photosynthesis making them solar powered!!
• Nudis are hermaphrodites and are ready for reproduction whenever they meet another nudibranch. This is because they move so slowly and it can take a while to meet others of their kind.
• They are carnivorous but don’t worry, they only eat sponges, coral, anemones, hydroids, barnacles, fish eggs, sea slugs, and other nudibranchs

Are you interested in nudibranchs? Maybe you have a favorite species or features you’ve seen on one? We’d love to hear about your nudibranch encounters so leave us a comment in the box below.