Thorunna horologia and friends?

Dear Valda,

These 'critters' are caprellid amphipods - sometimes called 'skeleton shrimps' because of their shape. I have discussed a little bit about caprellids and their association with some nudibranchs in an earlier message [#19058] and you'll find a few more examples on the Forum if you search for caprellid.  I have enlarged a couple of sections of your photo and one of them shows that the substrate and growths, on which Thorunna is crawling, are over-run with caprellids of various sizes.  I  think this is just a coincidence. If you have seen it often then perhaps the sponges that Thorunna feed on live in a place that caprellids find attractive.

On a seperate topic, your photo gives us a nice view of the purple oral tentacles. I noted in the original description of this species that specimens I had seen had the oral tentacles 'tipped with a washy purple' so it is good to get this character confirmed, as photos usually don't show it.

Best wishes,
Bill Rudman