After the success of the two Melbourne Sea Slug Censuses held last year, we are running the third Melbourne Sea Slug Census on Friday 15 – Monday 18 March 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 third Melbourne Sea Slug Census March 2019:


October 2018

Between Friday 12 – Monday 15 of October 2018 people all across Port Phillip Bay, Westernport Bay and surrounds submitted their photos of nudibranchs as part of the Second Melbourne Sea Slug Census.

We’re thrilled to announce the winners of our photography competition. Jack Breedon, whose spectacular image of Flabellina sp. (below) took out Best Photo by a very narrow margin. The competition was fierce with many wonderful photos in the running.

Caption: Jack Breedon’s image of Flabellina sp. won Best Photo for October’s Census

The prize for Most Interesting Find goes to Rebecca Lloyd and Chris Hurwood for capturing this image of Dendronatus sp, as judged by Bob Burn. Bob has never found a Dendronatus sp himself, only aware of there existence through a couple of images and one specimen. We’re very grateful to Bob for lending his expertise in identification and sharing insights about these fascinating creatures. A big thank you to everyone involved- this includes those who submitted photos during this census and those who searched to no avail!

Caption: Rebecca Lloyd and Chris Hurwood’s image of Dendronotus sp. won Most Interesting Species


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