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Monday, June 5, 2017

Sparkling disco ball

Back in 2012, I showed a few pictures of a soft coral called Discophyton rudyi that we observed at Cape Mendocino (you can review those photos here).

In 2017, we found this species again at several locations in northern California and Oregon.  This time we also took some close-up pictures and Eric filmed a short video that we're excited to share.

Here's what Discophyton looks like up close.  Sometimes many of the polyps are extended, with tentacles spread outward:

Other times, most of the polyps are withdrawn, and it starts to look like a soft mound covered with little bubbles (the contracted polyps):

In the picture above, did you notice the granular texture surrounding each polyp?  The sparkling "grains" are sclerites, calcified structural elements that offer support and protection from predators:

[Note: A major predator of Discophyton is the nudibranch Tritonia festiva, which can often be found in close proximity.  Both are shown together in the photos from 10 May 2012.]

One way to recognize Discophyton in the field is to look for clusters of small disc-like mounds.  (Each mound is ~5-15 mm across.) The colonies can divide by fission, so it's likely many of the colonies in one area are clones (genetically identical).  In the photo below, can you find the splitting colony? A thin connection remains between two patches that are pulling apart from each other.

Yes, that's it!  The splitting colony is in the center of the picture.

The color of Discophyton can vary from white to pink to yellowish.  Note that this species is often found in shaded locations, e.g., under rock ledges.

And here's the video clip you've been waiting for.  Watch for subtle movements of the coral polyp tentacles.  At 10 seconds, in the upper right, look for one of the polyps to draw one tentacle down towards the center of the polypthis motion moves prey caught on the tentacle to the mouth:

Although they're not necessarily conspicuous, it's nice to know this beautiful soft coral is a member of our local fauna.


Maggie R. said...

Named after my father, Jerry Rudy!
(Who also follows your blog)

Jackie Sones said...

Hi, Maggie!

I had been reading about where the name "rudyi" came from, but I had no idea there was anyone reading the blog who had "Rudy" connections. It makes me smile to know that your father has seen these photos. How amazing to have such a beautiful coral named after you!