Nudibranchs, The Rock Stars Of Our Oceans

Article | Updated 8 months ago

Brightly coloured and slow-moving, these creatures are pretty easy to identify and hard to forget once you’ve seen them. Nudibranchs are mesmerizing sea slugs that gracefully slither across our oceans.

Underwater Jewels

Nudibranch translates to naked (Nudi) and gills (branch) in Latin, due to their frilly exposed gills. You may have seen them making their rounds on social media – often being compared to David Bowie.

Despite being rock stars in their own right, they aren’t just pretty faces.
Some have chemical defences to ward against predators while others are able to mimic the colourful warning signs of their more poisonous friends. Clever.

They’re fussy eaters – feeding on only one or two sponges. While there are plenty of nudibranchs with fantastic compounds being used in cancer research, there is still much to learn about how nudibranchs contribute to the ecosystem. 

They’re big enough to be seen, and slow enough to be photographed – making it a dream for underwater photographers.
 

A close up of a nudibranch

Goniobranchus leopardus
Image copyright WA Museum 

Key points:

  • Nudibranchs are brightly coloured, soft-bodied molluscs with dazzling colours selected by nature.
  • Genetic tools are now used to understand the evolutionary histories of these species.
  • Goniobranchis aurigera, was only found once in 1990 at Quinns Rocks, north of Perth City.  

Genetics To Study Life Histories

Dr. Nerida Wilson, Western Australian Museum’s Molecular Systematics Unit Manager and Senior Research Scientist, uses genetic tools to study these colourful creatures.

Genetics provides us with the finer grain picture, especially with cryptic species

Dr Wilson

What this means is that, before genetics, when organisms looked the same, we would have assumed they were the same thing. With fancy high-tech genetic equipment, we can now understand these organisms on a molecular level. What’s interesting is, things which look similar may have been diverging for millions of years and aren’t that similar after all.

If we want to conserve and understand things properly, we need to use the best tools possible, and genetics allows for that to happen

Dr Wilson

Dr. Nerida Wilson diving underwater

Dr. Nerida Wilson hard at work
Image copyright WA Museum 

One Hit Wonder

Back in 1986, one lone specimen of Nudibranch, Goniobranchis aurigera was found off Quinns Rocks. Mysteriously, the same species was never found again. With a whitish pink body and yellowish gold stripes across its back, its distinct characteristics made it unlike any nudibranch that was found before.

Species aren’t typically described based on one specimen, but an exception was made for this species since “it was very unusual looking and wasn’t mixed up with anything else”. Dr Wilson had hoped that she would one day be able to get her hands on this species and run genetic sequencing to find out what it’s related to.

Goniobranchis aurigera nudibranch underwater

Goniobranchis aurigera found in 1986
Image copyright WA Museum 

The next time you get in the ocean, be sure to keep your eyes peeled for these charismatic creatures.

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Siti Mutaza – Science Communication Practicum
University of Western Australia Student