I understand that I'm asking for a lot given how awful the quality of this image is, but I think it makes the bizarre body shape of this crustacean quite obvious. I've really seen nothing like it with what I think were two large outer claws and a pair of smaller inner ones, some tiny legs behind and a head that hardly protrudes from the base of the body at all!
What this photo doesn't show given the colour dilution of the water coupled with the animal's very small size is that it was a shade of red.
Even weirder was the presence of another individual (a younger one or a slightly different species?) that had the same rough build only everything (body, limbs and all) were much skinnier, and it was brown. Impossible to photograph as any attempts at doing so from a phone made it merge with the rocks.
@Newzooboy that’s a good shout. Looking at photos online though it seems as though most squat lobsters have small tails, whereas I’m not sure if this creature had anything. It’s hard to judge in the photo, but to me it definitely seemed wider (leg span) than it was long.
Fair point - although I think the body is probably curled under, making the whole carapace appear shorter. Of more concern is the middle 'pincers' - which are seen in some lobster species (although not squat lobsters), but not usually in crabs.
I'm now thinking it might be a Decorator Crab - Camposcia retusa
This would mean the larger 'outer claws' are just walking legs that look big owing to the algae, etc. attached - did you notice if they actually had pincers on the end?
This might explain the difference between the individuals you saw - if the larger one had was covered with mainly red weed, and the smaller one had yet to cover itself?
@Newzooboy that's a great guess, I hadn't heard of the species until now. The fact that decorator crabs cover themselves in weeds and corals would explain the knobbly appearance of this creature and the illusion given of some of its bumps being plants. It also makes more sense that one of the individuals was a much blander colour with no protrusions.
As for the outer pincers, I can't remember, but looking through all the various photos I took none of them make it clear that they are pincers. I just assumed this looking at photos given that the ends of its arms are different colours to the rest of it as pincers would be.
My only slight doubt is that Camposcia retusa does not reside in the Mediterranean, which is where all of Napoli's animals (as far as I know) are found, with the nearest population being in the Red Sea. A short-lived crustacean doesn't feel like something they're likely to import from somewhere far away, but then of course if this species is present in private trade then they may well have been confiscated or donated (which would then explain why they're in a rather makeshift-looking, unsigned tank).
Many thanks for your help in solving this mystery! It has bothered me very much for the past week and I am satisfied to have finally found a likely answer.
No problem. I enjoyed the challenge.....and once you start down this kind of road...
I agree on the distribution - that what was throwing in me initially, as I have visited Napoli Aquarium a couple of times and was aware of the Mediterranean (even Bay of Naples) focus.
Looking at my photos from last visit (2023), however, suggested they do keep some tropical species.
I wondered about a Mediterranean equivalent, but couldn't find any indication that such a thing exists, and Camposcia is monotypic.
@Newzooboy the closest I could find to a Mediterranean equivalent was Macropodia rostrata, but that species seem to mainly cover itself with algae rather than sponges or coral and therefore looks much thinner, just slightly ‘fuzzy.’
When you visited, were these makeshift-looking tanks in place yet? They are the very small box-like ones, immediately to the right of the entrance, with no signs and a blue wall surrounding them, if that rings any bells.
@Kalaw yes, I saw that species in my searches too - it could be that I guess, but your picture certainly looks more like Camposcia.
I don't remember the small tanks near the entrance, and I have no pictures of them - the latter of which suggests they were not there in March 2023.
I thought one of the main tanks held more tropical reef species though, I have pics of tropical fish, such as the Threadfin Butterflyfish.....so not entirely Mediterranean focused (unless they have changed that in the last two years or so).
