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Monday, August 4, 2014

Oh! Henry!

I know I just showed pictures of a juvenile sea star, but this is an interesting story, so I'm going to include a few more tonight.

There have been some notable things washing up on local beaches recently, so Eric and I decided to go for a walk to check a few of the kelp holdfasts.  We brought one holdfast back to document some pelagic nudibranchs (more about them in a future post), but while looking through the microscope I was surprised to see a tiny sea star emerge.  "Oh!  A sea star!" I said out loud and when Eric looked, he said, "It's Henry!"  That might sound strange at first, but "Henry" is our nickname for "Henricia"— the genus of a small sea star.

Here's the juvenile sea star viewed through a microscope (below).  It was less than 4 mm across:


Then Eric and I realized that we were looking at different individuals.  He had spotted a second sea star in a slightly different location.  And then when I surveyed further, I found a third!  Below are the second and third individual Henricia from the kelp holdfast.



So why is this interesting?  Well, we've looked at a lot of holdfasts during the last couple of years, and this is the first time we've observed Henricia in one of them.

Henricia is also one of the species that seems to have been impacted by a harmful algal bloom in 2011, so they've been difficult (if not impossible) to find during the last few years.  These are the first individuals we've seen of this species in a while.  

It's also worth noting that there were at least three individuals in one holdfast.  It's hard to know if this is significant or not.  Some species of Henricia are brooders and others are broadcast spawners.  I'm not sure which species this is, but if it's a brooding species, these individuals could be siblings.

And!  Note that this holdfast also had pelagic barnacles (Lepas sp.) growing on it (there's one in the second photo below the sea star).  This means that the holdfast had probably been drifting offshore for a while and it (and possibly the sea stars) could have rafted from a distant source.

1 comment:

Anonymous said...

I love the kelp holdfast stories. In fact, your stories of discoveries made in holdfasts inspired one of the independent student research projects in my OIMB marine ecology course this summer. I'll report back on findings next week! :-) -AH