These tiniest of hermits grow to fill an approximately 1/4 inch long shell, never more. I thought at first that they might have been immature hairy hermits that would darken as they grew, but I never see them move on to larger shells.
They have orange legs with white bands. Sometimes they are big enough for me to see the antennae with the naked eye; it is green, with white bands. The legs and body are very slightly hairy.
I've struggled, over the years, to find a clear identification of these hermits. At first, I was calling them greenmark hermits, Pagurus caurinus. A sort of match, at least for the orange colour and the size. And maybe some were greenmarks. But not all.
|One of the larger ones, still tiny, on an oyster shell. Not a greenmark.|
The greenmark hermit sometimes has the orange legs, and are tiny, but their antennae are red and unbanded. These have green, banded antennae and white pincer tips.
I saw one out of his shell, freshly molted, and out looking for a larger (grain of rice sized) one.
|Pink striped body, purplish rear end, green banded antennae. Not a greenmark. Another in the background. Their legs are always clean, the colours sharp.|
I've searched everywhere I could think of; I can't find the match to this. There's another tiny orange hermit in this area, growing to 0.6 cm as an adult, the Brilliant, Parapagurodes hartae, but he is a brilliant orange all over, with little white banding. And I think, from the photos, that the antennae are orange, too.
|Another. The one in the background from the previous photo.|
The last crop of rockweed and a shell-full of sand brought a fresh batch to my tank. There must be at least a dozen, all racing around, climbing on and over everything. Cute little critters!