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19

The last of my Pisaster ochraceus stars waited until today, three whole days after all of its conspecifics had died, to start ripping itself into pieces. This is the sight that greeted me when I checked on my animals this morning:

My last Pisaster and its autotomized arm ©2013 Allison J. Gong
My last Pisaster and its autotomized arm
© 2013 Allison J. Gong

I spent some time examining the severed arm because it is freakishly fascinating to watch autotomized parts continue on as though they were still attached to the main body. They literally don't know that they're dead.  I've seen almost completely eviscerated sea urchins lumber around a seawater table on about 10 tube feet for days before finally giving up the ghost. This arm remained very active for quite a while--at least an hour--before I gave up and threw it away.

While I had this severed arm in a bowl under the dissecting scope I thought I'd take a few photos of the surface. Beautifully complex animals, sea stars are, when you look at them up close.

View through dissecting microscope of aboral surface of arm of Pisaster ochraceus. ©2013 Allison J. Gong
View through dissecting microscope of aboral surface of arm of Pisaster ochraceus.
© 2013 Allison J. Gong
Oral surface of arm of Pisaster ochraceus, showing tube feet. ©2013 Allison J. Gong
Oral surface of arm of Pisaster ochraceus, showing tube feet.
© 2013 Allison J. Gong

Meanwhile, the remaining 4/5 of the star continued to walk around the table. It ended up behind one of the quarantine tanks in which I had sequestered the bat stars, where over the course of the next couple of hours it dropped another arm. Because of its location I wasn't able to get a decent photo of it, but here is a shot of the wound from the first autotomization:

Wound caused by autotomy of an arm in Pisaster ochraceus. ©2013 Allison J. Gong
Wound caused by autotomy of an arm in Pisaster ochraceus.
©2013 Allison J. Gong

And I'm not the only one at the lab dealing with this disease outbreak. The lab next door is losing a couple of stars, and the Seymour Center lost one of their Pycnopodia helianthoides (sunflower star) yesterday. And, I heard second-hand that a student in the Santa Cruz area saw some dying stars on a dive in the past few days. What happened in my seawater table over the past few weeks may be just the beginning of something really, really bad.

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