With five successful Melbourne Sea Slug Census events to date, our records of sea slug species found in and around Port Phillip Bay and Western Port are continuing to grow. Collecting photos of sea slugs present at different times throughout the year will help us monitor these species and track any changes, but we’ll need your help!

The fifth Melbourne Sea Slug Census was held over Friday 4 to Monday 7 October 2019. We had a massive response from our nudi loving community, and have nearly 400 photos to sort and identify! Thanks to everyone who submitted their finds, there will be a report for October 2019 to come.

The next Melbourne Sea Slug Census will be in 2020, between Friday 17 and Monday 20 January. If you are out and about 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.

Caption: Tambja verconis, a nudibranch commonly spotted in Port Phillip Bay. Photo Liz Harper

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 nudibranchs, 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 sixth Melbourne Sea Slug Census, 17-20 January 2020!

Info for Melbourne Sea Slug Census VI

To help our experts with their identification, try to get a clear shot of the slug’s body from the side and/or include as many creature features (rhinophores, gills/cerata, oral tentacles) as possible. As always when out and about in nature, be mindful of limiting your impact on your subject and their surrounds.

June 2019

Between Friday 7 – Monday 10 June 2019 people all across Port Phillip Bay, Westernport Bay and surrounds submitted their photos of nudibranchs as part of the fourth Melbourne Sea Slug Census.

Conditions over the weekend were challenging, and the slugs were relatively scarce. However, we did still receive records of 29 individual species. Well done to everyone who was out and about, and even if you didn’t find a single nudibranch, side-gill or sap sucking sea slug we hope you enjoyed exploring a different side of our wonderful marine environment at this time of year.

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

Winter Warmer Award: Karen Barwise (Ceratosoma amoenum, Boarfish Reef)

  • Voted by Bob Burn and the ReefWatch team for its warmth, composition and clarity, this photo of a Ceratosoma amoenum was a perfect remedy for the chilly conditions of the June census. Bob thinks this is a lovely species, and we agree. Well done Karen.

Photo: Karen Barwise

Most interesting species: Nick Shaw (Aplysiopsis formosa, Sorrento back beach)

  • This introduced species has different patterns on each side of its cerata, which Nick was able to capture in this beautiful shot. Well done Nick.

Photo: Nick Shaw

Honorable mention- Slugging it out for Science: Nick Shaw (Facelina sp. RB3, Point Lonsdale)

  • Our experts can’t stress enough the importance of clear photos that capture the body shape of the slugs you find, as this will help them identify them- many slugs can look very similar, and it may come down to the shape of their mouthparts, or the texture of their rhinophores, to tell them apart.
  • This relatively drab nudibranch may not win any beauty contests, but Bob Burn singled it out as a great shot for identification as it clearly shows the colouring, shape, relative size and many of its defining features.

Photo: Nick Shaw

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.

Our next Melbourne Sea Slug Census will be held between Friday 4 to Monday 7 October 2019. The October Census of 2018 was massive for sea slug diversity, with 75 species spotted. Here’s hoping our nudi hunters can find even more this year!

June 2019

Our winter wonderland edition of the Melbourne Sea Slug Census saw many people brave the cold water, but only 6 groups of nudi hunters managed to photograph slugs during that time. Still, 29 species of slug were sighted, with some really beautiful submissions and new species to add to the Melbourne census records. A commendable effort for a very chilly weekend!

Download full report for June 2019

March 2019 

Melbourne Sea Slug Census III was held over the 15-18 March. Many groups reported seeing far less slugs than expected, but all in all, over 100 nudi hunters that were out and about across the weekend recorded 48 individual species between them. Well done everyone!

Download full report for March 2019

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