Tiny but mighty

One of the delights of being a diver is spotting a nudibranch. While the concept of seeing majestic pelagics like dolphins, manta rays, sharks and whales are often on a diver's initial bucket list, many are increasingly enchanted by these tiny, colourful inhabitants.

At Wakatobi, your dive guide might signal you to come closer, and point out something so tiny you have no idea what they are pointing at - then you see it! A tiny slug, no larger than an inch, perched on the reef, adorned with rhinophores and cerata and swaying gently in the current. 

Before long, you begin to notice that these creatures, with their electric blues, vivid purples or fiery oranges, are everywhere.

What is a nudibranch?

Nudibranchs are soft-bodied, mucus-covered sea slugs with unique anatomies. They belong to the phylum Mollusca and class Gastropoda. Unlike many other molluscs, they lack a shell. Their bodies are often highly colourful and adorned with various appendages.

The most noticeable appendages are the rhinophores, which are sensory tentacles on their heads that help detect chemicals in the seawater, locate food, and find mates. Their cerata are branch-like structures along their back, which serve multiple purposes, including respiration and defense. Nudibranchs also have a foot, a muscular organ used for movement, and a mantle that covers most of their body. They possess a simple digestive system and, depending on the species can have specialized feeding structures such as radula (tooth-like structures) for scraping and tearing food from surfaces. Their vibrant colors are often a warning to predators about their toxicity or bad taste.

Some of the most commonly seen are nudibranchs in the Chromodoris group, beginning with the Chromodoris Willani nudibranch identifiable by their striking light blue and white body with super dark blue dash like markings down their back.

For more on what you can see underwater at Wakatobi, visit wakatobi.com