111127 Little Sisters Island

Was primarily looking for crinoid commensals.


The most common crinoids wer these red ones.


Tiny brittlestar on one of them. Not sure if it really is a symbiont.












These worms are likely to be Myzostomida, obligate symbionts of echinoderms (very commonly crinoids), a symbiotic relationship that goes back a very long way (to the Ordovician period, over 400 mya), so long that it resulted in them developing peculiar anatomical features inconsistent with their phylogenetic placement (recent genomic studies have suggested that they are part of the annelid radiation but the results are still not conclusive).

Myzostomida come in a few types, some reside in their hosts while others cling to the outside. The external ones can be further separated into those that move about freely on their hosts, those that sit mainly at the disc of the crinoid, and elongate ones which cling to and move along the crinoid arms and pinnules.




Strange worm that was swimming at the surface while the tide was coming in.


Pteraeolidia ianthina.


Phyllidiella pustulosa.


Land hermit crabs are the cutest. This individual was difficult to photograph as it kept advancing towards the camera.