Australasian fishes

I believe that most divers, who enjoy fish, have their favourite species. Looking at Australasian Fishes observations it is clear some members are passionate about seahorses, others about weedy seadragons, etc. Personally, I find the antics of blue gropers very entertaining, and will often stay longer in the water, watching them bully their neighbours, even after I have lost the feeling in my extremities from cold. Developing a passion for certain species is one of attributes of an iNaturalist user.

Another attribute is reciprocity. Richard Leakey, the famous archaeologist was once asked about the things which make us human, and he responded that it was reciprocity. When our ancestors decided to share food and skills, we started on the road to becoming humans.

Favourite species and reciprocity play a large role in successful citizen science too. While not necessary sharing food (sadly) we are sharing skills (photographic, scientific, taxonomic), creating a strong feeling of reciprocity, whereby, we feel grateful for those who assist us with difficult identifications, and we respond in kind.

This brief article is about a project member who combines both of those attributes, sharing one of their favourite species with citizen science and striving to improve iNaturalist’s data base, to ensure observations are VERY accurate. Australasian Fishes is regarded as one of the leading fish data bases in terms of accuracy of identification. Something which we should all be proud of and Graham McMartin (@grahammcmartin), illustrates why this is.

Graham’s current passion, however, is not for a particular fish species, although he is an active contributor to Australasian Fishes, but for a familiar and comical little hermit crab. This passion has taken him on a personal journey which will enrich iNaturalist and the value of the citizen science we perform.

In Graham’s own words, “I did my open water dive course at Little Beach in Nelson Bay in the early 90’s but was heavily involved in my main sport of 16ft skiff sailing and didn’t get serious enough about diving to buy my own gear for about a decade. A good dive buddy convinced me to take on the challenge of learning underwater photography in 2008, by gifting me his old Olympus C740 camera and housing, when he upgraded. Once I had worked out the camera basics, I suddenly found diving much more interesting as I had a visual record of everything I saw and everywhere I’d been, which could let me enjoy a good dive over and over. I might also say it also made me a technically better and more aware diver. I took that camera for a two-week trip to the President Coolidge wreck in Vanuatu in 2009 and was completely hooked.

Roll on 10 more years (and a couple of camera upgrades) and the same dive buddy, Matt Dowse (view Matt's profile), got me involved in iNaturalist. I had only posted a handful of images when Mark McGrouther popped up and invited me to be a part of the Australasian Fishes project. I was stoked to find a forum where all those images from past dives could be of interest and use to others. It has been a fantastic learning experience - I have learnt more about underwater life in the last two years, than in the twenty-two years before that! Key to this was interacting with all the great people who populate the site, both divers and non-divers, citizens and scientists, who willing share their knowledge and experience.

I might also say, it’s been great fun - working my way through images to post from some memorable overseas trips, such as Truk Lagoon, Rabaul in PNG and the Solomon Islands (yes, I’m also a wreck junkie). I have also re-visited some awesome dives over the years closer to home, such as Fish Rock Cave, Broughton Island and Bait Reef on the GBR. An observation I am most proud of though, came on a day of lousy viz in my own backyard- under Swansea Bridge, where I came face to face with a metre long Queensland Groper (view observation), well out of his backyard! He was definitely the largest fish I have encountered under the bridge and seeing his bulky outline appear out of the murk certainly got the heart rate up! He was decidedly unimpressed when my strobes went off right in his face and I used up most of the remaining 20 minutes of slack water, before the run-out tide became too strong, to get close enough to him for a second image.

My interest in Dardanus hermit crabs came about last year, as I began identifying Dardanus crassimanus as the predominant large hermit crab in Swansea Channel. They are very photogenic and seemed to be real characters! By appearance, the average diver would describe them as a ‘hairy red hermit crab’, but there are some obvious differences with ‘the’ Hairy Red Hermit Crab – Dardanus lagopodes - as presented on iNaturalist.

For my observations, the correct ID for both these species came from Kuroshio in Japan (both species are also found there) via Tony Strazzari (@tonydiver), who had posted many observations of them, before discovering their true identity. Dr Matt Nimbs provided an expert confirmation, as both these species are found together in his home waters at the Solitary Islands, near Coffs Harbour. I note from my research now that both Ian Shaw (@ralfmagee) and John Turnbull (@johnturnbull) had correctly identified D. crassimanus some years ago.

During our time in covid lockdown last year, I had identified a couple of hermit crabs for other iNat members and began to look at observations that had been posted in the past. I found many D. crassimanus observations from NSW waters were either incorrectly identified as D. lagopodes, or not identified at all. With my newfound ability to tell the species apart, I thought I may as well work on fixing this. As this work progressed, one fact became apparent - whilst both species are found together at the Solitary Islands, D. crassimanus, being a temperate species, does not appear to be found much further north than this (Qld border), whilst D. lagopodes, a tropical species, is not found further south.

Another development was my discovery of several unidentified iNat observations of D. crassimanus in South Africa by marine naturalist Georgina Jones (@seastung). Matt Nimbs followed up with some research and confirmed the species is known in these waters, according to the South African Museum. We have also been able to positively ID a couple of observations of D. crassimanus on the temperate Western Australian coast, close to Perth, demonstrating these hermit crabs certainly have a wide range, across two different oceans. I see my efforts as an interesting opportunity to do a bit of ‘citizen science’ that could improve the accuracy of identifications on the iNaturalist website and to contribute more than just my own observations.

The next thing I would like to achieve with this little project would be to get the ‘common name’ for D. crassimanus - as stated by the Queensland Museum, accepted for identifications on iNaturalist. The name – quite appropriately - Mauve-eyed Hermit Crab. Perhaps Harry can help with this!”

Thanks Graham, I am working on the slogan and rough T-shirt designs now. For a slogan, how about “Call them Mauve-eyed Hermit Crabs, but never late for dinner!” I too have benefited from Graham’s work in cleaning up the hermit crab data base, and I appreciate all the work and research which has gone into this project, by a citizen scientist.

This journal post was written by Australasian Fishes member, Harry Rosenthal.