After the success of the three previous Melbourne Sea Slug Censuses, we are running the fourth Melbourne Sea Slug Census on the Friday 7 June to Monday 10 June 2019. If you are out and about in Port Phillip Bay, Western Port Bay that weekend and you come across any Sea Slugs, we want to know what you find. Images of Sea Slugs found during these dates can be sent to [email protected]
See Get Involved below for more details.

In Partnership:

The Sea Slug Census is supported by the Victorian Government.

What is a sea slug and how will you know if you’ve found one?

Sea slugs are actually snails i.e. they are sea snails (marine gastropod molluscs) that have seemingly lost their shells. Also known as nudibranch, they are found in most marine habitats, occurring in shallow rock pools and in the deep sea. Knowing when you find one can be easy when they are the size of a football, or extremely difficult when they are smaller than the nail on your pinkie finger. Generally, if it is in saltwater and it moves like a slug it is most likely a ‘sea slug’. If you are unsure, take a photo and we will let you know.

Sea Slugs are one of the most popular and most photographed groups of marine invertebrates, with ~400 species known in Victoria. They are excellent indicators of environmental change because they have rapid life-cycles (less than 12 months), very specific food requirements, and respond to changing oceanographic conditions.

Yet there is very little basic knowledge on their diversity, distribution and ecology. To learn more about them we teamed up with Southern Cross University to have Victoriaís first Sea Slug Census in Port Phillip Bay, Westernport Bay and surrounds. The information gathered will help marine scientists to update knowledge about the diversity and distribution of this spectacular group of molluscs.

To learn more about sea slugs in Victoria, check out these links:

A Museum Victoria field guide – Nudibranchs and related molluscs

Port Phillip Bay Taxonomic Toolkit

Australian Geographic – Nudibranchs: indicators of climate change

Facebook group for nudi-nerds!

Everything you need to know about the fourth Melbourne Sea Slug Census June 2019!

Info for Melbourne Sea Slug Census IV

March 2019

Between Friday 15 – Monday 18 March 2019 people all across Port Phillip Bay, Westernport Bay and surrounds submitted their photos of nudibranchs as part of the third Melbourne Sea Slug Census.

This time was no exception, and we had some terrific entries. There were some returning champions as well as first-time entrants, and while many people said they had a harder time finding sea slugs this weekend than usual, we still have some new additions to our Census records for Victoria. We’re also starting to get spoilt for choice when it comes to great images to use in educational materials such as ID charts, and a booklet that is in the pipeline.

We’re pleased to let you know the winners of the third Melbourne Sea Slug Census photo competition!

Best Photo: Nick Shaw (Phyllodesmium macphersonae, Pt Lonsdale)

  • The people’s choice award in a blind vote held at the VNPA office, and it’s not hard to see why. We love how vibrant this aolid nudibranch is against the dark background, and this photo also shows off its distinguishing features and body shape.
Caption: Photo: Nick Shaw

Best Ceratosoma brevicaudatum: Roy Joyce (Blairgowrie)

  • 12 different groups of nudi hunters found this species at least once, making it the most sighted in the March 2019 Census, so we figured it deserved its own category!
  • This photo beautifully showcases the creature features of this common dorid nudibranch, also known as the Short-tail Ceratosoma, including the eponymous red ‘tail’ that acts as a focus for predators (who get a mouthful of nasty chemicals if they take a bite). VNPA staff loved the clarity of the animal against its setting. It’s a great example of ‘best practice’ in photographing for identification purposes!
  • Honourable mention to Michael Gibbs for his brilliant overhead photo of a C. ceratosoma at Rye pier, the colours in this shot were spectacular.
Caption: Photo: Roy Joyce

Most interesting species: Chris Hurwood (photo below) and Rebecca Lloyd (Dermatobranchus rubidus, Blairgowrie)

  • Professor Steve Smith (founder, SSC) was most excited to see this species pop up in another Census, as it has only ever been recorded as part of the SSC once before.
  • We love the delicate shapes and colours of this nudibranch, which belongs to the ‘mixed-bag’ suborder Arminina (notable cousins being Madrella and Janolus species).
Caption: Photo: Chris Hurwood

Best group photo: Nick Shaw (Verconia haliclona, Blairgowrie)

  • Nick certainly got the most bang for his buck with this shot of at least a dozen tiny V. haliclona feasting on a sponge.
  • Honourable mention to Chris Hurwood for his close-up shot of a ribbon egg casing showing what he noted as “thousands of nudis ready for next census”.
Caption: Photo: Nick Shaw

Multi-species special: Chris Hurwood (Verconia verconis and Verconia haliclona, Portsea)

  • This is a fantastic contrast between the cryptic but relatively large V. verconis and the smaller, brighter V. haliclona, seen just sneaking into frame at the top of the photo. A great find.
Caption: Photo: Chris Hurwood

Super sleuth award: Rebecca Lloyd (Doto pita, Blairgowrie)

  • Rebecca estimated this tiny Doto to be about 3mm long, and given its near-perfect camouflage with its surroundings this is a very impressive find!
  • Rebecca also takes out honourable mention in this category with her shot of an orange Rostanga sp, also barely visible against the background of the sponge she found it on.

Thanks again to everyone who sent in photos, and anyone else who kept an eye out for slugs whilst they were out and about experiencing our wonderful marine environment.

Caption: Photo: Rebecca Lloyd

Our next Melbourne Sea Slug Census will be held between Friday 7 June to Monday 10 June 2019. While the weather may be chilly the tides are looking good, so if you’re planning to brave the cold for a coastal adventure, we’d love to see any sea slugs you find.

We’re pleased to let you know the winners of the third Melbourne Sea Slug Census photo competition! See their images above in Most recent Melbourne Sea Slug Census highlights tab. Stay tuned for the release of the official report.

October 2018 

The second Melbourne Sea Slug Census took place on the 12-15 October. Over four days, enthusiastic teams and individuals managed to find an incredible 75 species of sea slugs! It was a fantastic effort and the overall quality of images submitted impressed everyone involved in sorting and identification. Some of the species photographed during this Census have rarely been seen in Victoria, even by our leading experts!

Download full report for October 2018

April 2018

The first Melbourne Sea Slug Census was held on the on the weekend of 21-22 April. Thank you to the over 150 people who photographed different sea slugs (nudibranchs) in Port Phillip Bay, Western Port Bay and surrounds and submitted them to ReefWatch. Together, we found a total of 53 species of nudibranch!

Download full report for April 2018

Support the 2018 Sea Slug Census with your own t-shirt.

Cost: $25.00
Cotton machine washable t-shirt locally printed from an ethical accredited supplier. Available in sizes S-XXL while stocks last.

T-shirts can be collected from the office or at a Sea Slug Census event (by arrangement) at no cost. Alternatively, T-shirts can be delivered to you for $5 each.

Purchase from our online store

Nicole Mertens, ReefWatch Project Officer