Sea Slugs are sometimes called the butterflies of the sea, but they’re more than just a pretty face! Not only are they adorned in a bewitching spectrum of colours, they’re also excellent indicators of how our environment is changing.

With nine successful Melbourne Sea Slug Census events to date, our records of sea slug species found in Victorian coastal waters are continuing to grow.

Collecting photos of sea slugs present at different times during the year helps us to monitor these species and track any changes. But we need your help!

UPDATE: MARCH CENSUS EXTENDED, NEW PLATFORM FOR SUBMISSIONS

The March Melbourne Sea Slug Census was extended. It ran between 25 March – 3 April – that’s 10 whole days! If you were out and about anywhere on the Victorian coast during this time and you find a nudibranch, sacoglossan, or other sea slug, share it with the Census.

In other exciting news, we’re moving to iNaturalist as the platform for submitting and collating Sea Slug Census data. This will allow the project founders to compare data from Censuses held around the country, as well as providing open access to the images that are being submitted.

Check out the March Sea Slug Census on iNaturalist

iNaturalist is a great community of experts and enthusiasts that can help you hone your identification skills and learn more about all kinds of wonderful wildlife. If you’re not already on the platform, you can head here for a guide and videos to help you sign up and start uploading your valuable images!

Please note: the guide has been created for our Marine Life of Victoria project, but the steps for joining iNaturalist still apply. Your sea slug images will automatically be added to the March Census if they meet the criteria (a sea slug taken anywhere along the Victorian coast during Census times).

Learn more about iNaturalist and how to upload your photos here

If you’re heading to the coast during this time, please remember to follow all advice from health and environmental authorities around social distancing, access to sites and water quality, and make sure you’re complying with current COVIDSafe restrictions.

More information about current restrictions can be accessed at the Victorian government coronavirus page and Parks Victoria. Take care and stay safe while enjoying our wonderful wild places.

You can download the guide to taking and submitting photos to the Census here.

Recent Melbourne Sea Slug Censuses

We held the Eleventh Melbourne Sea Slug Census between the 28 – 31 January 2022. Once again we had over 80 people take part in a sea slug search or otherwise submit their photos. 17 teams or individuals found 70 species of sea slug! The report for January is now ready to view.

The Twelfth Melbourne Sea Slug Census ran from 25 March through to 3 April. We’re currently still accepting submissions to our iNaturalist project– any Victorian sea slug images uploaded to iNaturalist from these dates will be automatically added to the Census records for March.

 

In Partnership with the Melbourne Sea Slug Census:-

The Sea Slug Census is supported by the Victorian Government.

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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 Victoria’s first Sea Slug Census in Port Phillip Bay, Westernport Bay and surrounds. The information gathered during Sea Slug Censuses 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 and info on SSC events around the country (and world!)

Contributing to this project is simple! All you need to do is take a photo of any sea slug you see if you’re out and about on the coast during Census times. Your photo will be identified by experts to confirm when and where we are seeing different species of sea slug in Victorian waters. All data from the Melbourne Sea Slug Census goes towards the Sea Slug Census project, a community based initiative to document the biodiversity of our oceans through collaboration between divers and scientists. See the Sea Slug Census facebook group for details on other Census activities being held all around Australia- and even further abroad!

Thank you all for your continued support of this project and understanding during these challenging times. The next Sea Slug Census will be held between the 25 March – 3 April 2022. If you are heading to the coast during this time, please remember to follow all advice from health and environmental authorities around social distancing, access to sites and water quality in your area, and make sure you’re complying with current COVIDSafe restrictions. Take care and stay safe while enjoying our wonderful wild spaces.

Download guidelines for the March 2022 Census

More information about current restrictions can be accessed at the Victorian government coronavirus page and Parks Victoria. Take care and stay safe while enjoying our wonderful wild spaces.

Photographing sea slugs for identification:

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.

A note on water quality if you’re out exploring our coast:

Heavy rain can impact water quality on our coasts, especially after fires and periods of smoke haze. In general the EPA recommends avoiding swimming near stormwater or river outlets 24–48 hours after heavy rain. Within Port Phillip Bay, you can check your local beach conditions at the Yarra and Bay Beach Report- https://yarraandbay.vic.gov.au/

In the lead up to the Winter 2021 Melbourne Sea Slug Census we heard from Professor Steve Smith, the founder of the nationwide Census project, on how our slug shots are helping better understand nudibranch biodiversity and where to next.

We were also treated to a series of tips, tricks and stunning photos from a panel of passionate sea slug spotters. These are the kinds of nudi nerds that cast their keen eyes over reefs, piers and rockpools every time there’s a Census so if you’ve ever wanted to know how, when and where to find sea slugs watch the videos below! We hope these talks inspire you to keep a look out for sea slugs on your next coastal adventure.

 

The Sea Slug Census: a citizen science program to document sea slug biodiversity and distribution

Professor Steve Smith of the Sea Slug Census project gives us an overview of the sea slug groups, why he was interested in using citizen science to study them, how the project has grown and what he’s learned from 66 Sea Slug Census surveys and counting! He also lets us know what happens to the data (your beautiful sea slug images) and plans for the future with this fantastic project that ReefWatch is delighted to be a part of.

Tips from a Seasoned Sea Slug Sleuth

Ian from the Victorian Sub-Aqua Group shares his 5 major tips for spotting sea slugs. Ian has been recording sea slugs at his favourite site, Blairgowrie, since 2017 and is up to over 120 species in the area alone! So it’s well worth listening to what he has to say about the way that you move, as well as what to look out for, if you want to observe these fascinating creatures on your next dive.

 

Snorkeling for Sea Slugs

Nick, another Census legend, gives us a different perspective on searching for sea slugs by taking us to the rockpools and sheltered bays that he regularly snorkels. He encourages you to think like a slug, talks about the best times and conditions to find sea slugs in shallow waters and near the surface, and shows us that persistence pays off.

Sea Slugs of East Gippsland

Holly from East Gippsland shares with us the colourful critters that can be found at places like Beware Reef, Mallacoota and Gabo Island. We learn that the slugs of eastern Victoria are a little different than the ones we find along the central bays areas and west coast and certainly worth seeing for yourselves!

 

Nocturnal nudibranchs and searching the seafloor

Rebecca is the Melbourne Sea Slug Census project’s reigning champion for finding slugs, spotting the most species in 6 out of 8 Censuses to date (and a PB of 60 species over one Census weekend). As part of her tips for locating sea slugs she talks about how many nudibranchs come out to play at night, looking for places that provide refuge for slugs to gather and using evidence of slug activity to hone in on a slug before you actually see it.

January 2022

In January, the wonderful folks from Otway Ocean Care hosted ReefWatch and some long-term Census contributors for a weekend of searching reef and rockpools with their community. Victorian National Parks Association’s Wild Families, Parks Victoria’s South Port Phillip team, Diveline Scuba Centre, and the Marine Research Group of the Field Naturalist’s Club of Victoria also found slugs at events held over the Census weekend, along with many other individuals and buddy pairs across the state. In all, we found 70 species of sea slug!

Download report for January 2022

Once more we’re very pleased to see representatives from most of the major sea slug groups. While we love nudis, it’s great that our photographers are also sending in some spectacular non-nudi species such as sacoglossans, side-gilled sea slugs and headshield slugs.

With both the quantity and quality of images coming through it is getting quite difficult for our experts to select just a few winning entries and honourable mentions for the categories of Best and Most Interesting photos!

Best Photo: Holly Baird, Aphelodoris sp.

Caption: Holly Baird’s Aphelodoris sp. is a great shot, showing all the major sluggy features in clear focus.

Holly has captured almost all of the slug and its major features in focus in this vibrant shot – as Bob Burn said when he chose it, this would be the perfect photo for identification if we weren’t dealing with a particularly tricky subset of dorids! Many of Victoria’s Aphelodoris species have very similar, overlapping external features such as the mottled pattern on the mantle, broken outline on the mantle edge, and dark gills and rhinophores. At any rate, it’s a great photo. Well done Holly.

Nick Shaw got an honourable mention for Best Photo with this fantastic shot of Phyllodesmium serratum. While a commonly spotted slug in our Census, this particular image shows great detail in the animal’s cerata and facial features. A great contribution to the Census.

Caption: Nick Shaw’s Phyllodesmium serratum also shows the identifying features of this beautiful aeolid in clear detail.

Most Interesting Photo: Jeremy Bishop, Eubranchus sp. 

Caption: Jeremy Bishop’s shot of this tiny, unusual Eubranchus caught Bob Burn’s eye- he didn’t think he has seen a match for it before.

Another unusual Eubranchus featured in the January Census. Bob Burn was impressed with the detail Jeremy captured in this tiny, unusual aeolid. While it bears similar features to several known but undescribed species of Eubranchus, it isn’t an exact match to any he’s seen before.

John Olden’s photo of a possible Doriopsilla sp. caught Bob’s eye for a honourable mention in this category. It could be one of the darker colour forms of Doriopsilla carneola, but Bob remarked that the mantle tubercules are quite pronounced, and look to be raised and hardened. Doriopsilla peculiaris has raised tubercules, but is described as being much softer in appearance (and feel) than D. carneola. It may not even be a dendrodorid! But again, it’s a very nice shot of the animal that captures most of the usual identifying features in focus! Well done John and Jeremy.

Caption: John Olden’s deep red dorid nudibranch had our experts stumped.

Most Slugs Spotted: Nick Shaw

Nick took out the title of Best Nudi Spotter for January with his 34 species. He was closely followed by Steven Kuiter with 27 species. Well done to both sea slug sleuths!

We hope that all the reports you can download below, as well as the information here, can help hone everyone’s ID skills and where to start looking if you want to find more sea slugs the next time you’re out and about.

Expanding the Census

Our feature creature for 2022 is Hypselodoris bennetti– a colourful chromodorid found from Southern Queensland right around into central Victoria, most commonly spotted in the east of the state. We wanted to highlight one of the species that you might not find in Port Phillip or Westernport bays. While we’re known officially as the “Melbourne” local organisers of the Sea Slug Census program, we’re encouraging people from all over Victoria to take part and help us learn more about when and where we find sea slugs right along our coastline.

Caption: Hypselodoris bennetti– one of the colourful chromodorids that can be found in sponge gardens and rocky reefs on the east coast of Victoria. Photo credit: Holly Baird

The next Sea Slug Census is our March 2022 Census – keep an eye out for slugs while you’re enjoying the sun and saltwater! If you are out and about anywhere along the Victorian coast between 25 March – 3 April be sure to send in your slug shots.

January 2022

Our first Census for 2022 saw the ReefWatch team join Otway Ocean Care at Marengo reef for some sea slug searches. Around the state, over 80 people joined in the Census fun. In all, 17 individuals or groups recorded 70 species of sea slug from over 300 photos, another fantastic effort.

Download report for January 2022

 

October 2021

With stay-at-home orders lifted, many people returned to the coastal places they loved just in time for our October Census. 18 individuals or groups submitted over 450 photos between them! In all, we recorded 92 species of sea slug.

Download report for October 2021

 

July 2021

Special thanks to the 8 teams or individuals who braved the chilly waters in between lockdowns to submit photos of 57 different sea slug species, from Port Phillip Bay to far east Gippsland. Capturing data from different times of the year, including during winter, helps us gain a better understanding of our southern sea slugs and their occurrence in space and time.

Download full report for July 2021

March 2021

36 teams submitted a total of 492 photos to the March 2021 Census, and 98 species were recorded. This is the most ever recorded for a Melbourne Census and included good representation of the major sea slug groups. There were quite a few first-time sightings to add to our records, and our database on Victoria’s sea slugs continues to grow. Many thanks to all the teams and individuals that contributed to this fantastic Census.

Download full report for March 2021

March 2020

250 photos were submitted to the Census for March, and with everything going on we had to rely on snail mail to get them through to our expert Bob Burn for identification and judging. We ended up recording 61 species of sea slug! And we’re still adding species to our project records each new Census. Well done everyone.

Download full report for March 2020

January 2020

Smoke from the recent bushfires had severely impacted much of the Victorian coast this weekend, but around 100 intrepid nudi hunters made the best of conditions and submitted over 200 photos to the Census. We still recorded 72 species of sea slugs! And the quality of photos made Bob Burn’s judging of the competition a tricky task. Thanks to everyone who submitted to our first true summer edition of the Census.

Download full report for January 2020

October 2019

What can we say other than we were blown away by the number of nudis spotted this time! 88 species to be exact, some new additions to our records and a few entries that left our experts pleasantly surprised. October certainly seems like a busy time for both our nudis and the keen citizen scientists who search for them!

Download full report for October 2019

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

Nicole Mertens, ReefWatch Project Officer