[Gaynor]

I found this hermit crab on our Silmar Project research transect on the Costa Brava. It looks like a sponge is covering the shell that the hermit has adopted, but I have never seen a sponge quite like this one. Any ideas?



There's also something that looks like a little twig sticking out of one end and a thin, soft strand, like when sponges extrude their guts to feed.

 

[Kirstie]

I've seen sponges like this (with pink spots on) over here, underneath the shells of hermit crabs, but only those who've made their homes in Painted Topshells. Not sure what sort of sponge it is, though.

 

[MarkP]

Looks like a parasitic anemone to me, but not the same colouration as the ones I've seen - have a Google image search and see what you think.

 

[mke]

Not the parasitic anemone - it is a cloak anemone, Adamsia carciniopados. The tentacles and disc are underneath the shell in which the host hermit crab is living, and it is the base and column that you can see spreading around the sides of the shell. The anemones very readily throw out sticly threads when disturbed.
More info here
Mike

 

[Divemouse]

I'd go with Adamsia as well. What do you mean about sponges extruding their gut? Never heard of it!