Adorable Crab…But What Is She?!

[OldRed1]

We inherited the most adorable crab as a hitchhiker on our live rock. I believe it is a juvenile porcelain crab, but I cannot find any evidence of crabs of that type wearing a protective shell. Any ideas?

 

[exnisstech]

Very cool. I love hitchhikers. Can't help with ID tho.

 

[ISpeakForTheSeas]

If that’s wearing half of a bivalve shell, then my guess is a “shellback” crab (yes, shellback is the common name for the group of crabs that engage in that behavior):

Personally, I like decorator crabs (and crabs with similar habits like the ones that carry sponges or bivalve shells on their backs) and sponge crabs (family Dromiidae). The box crabs like mentioned above are really cool too. There are also specimens like purse crabs (Persephona mediterranea) and swimming crabs (Portunus gibbesii).

The site below* lists most of these and a few others that might be cool (though I don't know how much room the larger ones would need).

True Crabs - Gulf Specimen Marine Lab

True brachyuran crabs have powerful chelae which they use to rip fish and even snails apart. To get pinched by one can be a memorable experience. Some swim, while others crawl, creep and sidle. It’s best to keep them in separate aquaria or they may eat your prized tank mates. Watch crab videos...

gulfspecimen.org

*Steve and his Animals beat me to the link.

A little more info on shellbacks in the quote below:

This is pretty much all the info I can find them, with a relevant but informationally lacking quote above the link:
"During the juvenile and adult period they inhabit the sand and coral bottoms from coastal areas, eating small invertebrates."

https://www.dnr.sc.gov/marine/sertc/HYPOCONCHA%20som.pdf

Unfortunately, I’m downright terrible at crab ID, so I have no idea on the genus/species, but - if it is wearing a bivalve shell - it’s a start.

 

[OldRed1]

If that’s wearing half of a bivalve shell, then my guess is a “shellback” crab (yes, shellback is the common name for the group of crabs that engage in that behavior):

A little more info on shellbacks in the quote below:

Unfortunately, I’m downright terrible at crab ID, so I have no idea on the genus/species, but - if it is wearing a bivalve shell - it’s a start.

This is a great place to start my search, thank you!