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Thursday, July 13, 2017

Stauro-gazing


Not much time tonight, but I think you can see why I couldn't resist sharing this photo.  It's one of my favorites of the year!

If you've been following this blog for a while, you might have seen this species before, but it's been several years.  This is Manania gwilliami, a beautiful staurozoan. [Staurozoans are now a separate taxonomic class within the cnidarians.  Sometimes they're informally called stalked jellyfish.]  It was found locally today in the rocky intertidal zone.  We didn't measure it, but estimate it was ~12 mm long.

Here's the entire animal:



This individual had beautiful purple highlights.  Check out this close-up of two tentacle clusters:



When looking at the tentacles, I noticed some whitish pads at the base of some of the tentacles.  Here's one view:



After doing some research, I learned that these are adhesive pads.  It is hypothesized that when the staurozoan releases its pedal disc (the base of the stalk) from the substrate, it sometimes holds on with these pads while it reattaches.  Since I haven't been able to find many pictures of these interesting structures, here's one more image.  Look for the swollen white areas at the bases of the front three tentacles:



I'm sharing these staurozoan photos with you thanks to Hao Hao, one of Eric's summer students at the marine lab.  Her curious eyes spotted it attached to a blade of algae in the intertidal zone.  Thanks, Hao Hao!

P.S.  For an introduction to staurozoans, review the post called "Twinkle, twinkle, little stauro" from 12 November 2012.