Okinawa Sea Creatures ~ Nudibranchs

Check out this beauty that is affectionately known as Pika-chu nudi.

It’s no secret that nudibranchs are one of the most commonly encountered marine animals in Okinawa, Japan. Nudibranchs have not only many varieties but they have some of the most interesting abilities. Some of these nudis are so hard to find as they are tiny like Candelabra nudibranch, which is only about 10-15mm in length. But because of their vibrant colours and varieties, they are, by far, the perfect models for underwater photography enthusiasts. Ask your diving instructor about Photography Speciality on how to spot and take great photos of them. (And! Just as I am posting this, SSI has introduced a new nudibranch identification specialty, ask us about it.)P5020017-scaled.jpg.webp

  1. They can survive by autonomy. They can detach their rhinophores, branchial plumage or a fragment of their mantle in order to save the core of the body. They will then regenerate later when they are healthier.
  2. They can eat toxic animals. They have powerful jaws to grate their food and store toxins in specialised cells as a defence mechanism.
  3. Some nudibranchs don’t need to eat. Some nudis like Blue Dragons have photosynthetic algae inside their bodies and they only need to eat about the first few week of their lives. After that, they “charge” their algae in their tissues from the light to survive.
  4. Nudibranchs support each other. Like the snails, they leave a trace on their paths to communicate others nearby dangers or potential partners.
  5. Both parents lay eggs. Nudibranchs are hermaphrodites, which means they have both female and male genitals. Once two nudibranchs encounter, they exchange their male gametes in order to fertilise their female gametes and they both leave pregnant, which doubles their egg counts.
  6. They are environmental heroes. Nudibranchs play a crucial role in marine ecosystems. They consume organisms such as algae and sponges, preventing their overgrowth to balance their habitats. Some species even have symbiotic relationships with other organisms providing shelter or camouflage.


There is so much more to be studied on these fantastic creatures and your dive guides know just the right places in local dive sites. They’re not just beautiful to look at. They are the proof that we have rich biodiversity in Okinawa, Japan that must be protected. But like any other marine animals, their habitats are being threatened by lack of education in marine etiquette (you can read up on diving etiquette here), overfishing, climate change and so much more. Let’s protect our ocean together so that we can enjoy these magnificent creatures.

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