Two weeks ago I found a peculiar crab in the intertidal zone in SW Florida. when found, the crab was not utilizing a shell. It was similar shaped to porcelain crabs found in our area, but with smaller claws (red tipped) and the 5th perepod was flipped up on the dorsal size of the carapace. The eyes were also uniquely positioned on the ventral side of the animal. Upon collection, the crab was observed carrying a cockle shell half. It fit particularly snug in this shell, which leads me to believe this is a commonly used shell for this species. Any assistance on identification and/or resources would be appreciated.
It is Hypoconcha, most likely H. arcuata. These are true crabs, or Brachyura, and belong to the same clade as the dromiaceans, also called sponge crabs. Although typically dromioid sponge crabs use their small P4 and P5 to carry an assortment of critters including sponges and ascideans, hypoconchids are special in that they carry bivalve shells instead, hence their smooth and flattened 'thumb nail' shape. There are six species in the genus: three in the Eastern Pacific, and three in the Western Atlantic/Gulf of Mexico/Caribbean region.The two other species that occur in Florida are H. spinosissima and H parasitica.
Hi Courtney Bennett ,
This is, without a doubt, a Shellback crab. Genius : Hypoconcha.
It seems like a Hypoconcha arcuata.
There is two more species in Florida (Hypoconcha parasitica and Hypoconcha spinosissima). I cannot see it properly but if there is a couple of littles spikes above each eye, then it might actually be a Hypoconcha parasitica, however it doesn't seem like it. Eitherway, it's a beautiful speciment!
Cheers,
Greg
It is Hypoconcha, most likely H. arcuata. These are true crabs, or Brachyura, and belong to the same clade as the dromiaceans, also called sponge crabs. Although typically dromioid sponge crabs use their small P4 and P5 to carry an assortment of critters including sponges and ascideans, hypoconchids are special in that they carry bivalve shells instead, hence their smooth and flattened 'thumb nail' shape. There are six species in the genus: three in the Eastern Pacific, and three in the Western Atlantic/Gulf of Mexico/Caribbean region.The two other species that occur in Florida are H. spinosissima and H parasitica.
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