A star is born!

Posted on by Allison J. Gong

I’m sorry. I had to go there. You didn’t really expect me not to, did you?

The reason, of course, is that today we got our first settled and metamorphosed Pisaster stars! We were doing our normal Monday water change when I noticed a teensy orange speck on the bottom of one of the jars. I used my beat-up old paintbrush to remove the tiny dot to a dish, put it under the dissecting scope, and saw this:

Metamorphosing ochre star (Pisaster ochraceus), age 48 days. 20 July 2015. © Allison J. Gong
Metamorphosing ochre star (Pisaster ochraceus), age 48 days
20 July 2015
© Allison J. Gong

From this picture it’s a little hard to see what’s going on. The entire body has contracted a lot, from a 2.5-mm larva to about 1/4 of the original size as a 600-µm juvenile, and become much more opaque. There are tube feet and spines as well as some remnants of larval body (the soft bits at the bottom of the animal) at this in-between larvenile stage.

Here’s a picture of a fully metamorphosed little star:

Newly metamorphosed ochre star (Pisaster ochraceus), age 48 days. 20 July 2015. © Allison J. Gong
Newly metamorphosed ochre star (Pisaster ochraceus), age 48 days
20 July 2015
© Allison J. Gong

I expect we’ll be seeing more tiny orange dots on the bottoms and sides of the jars in the next several weeks. At some point we will have to figure out what they eat and provide it for them. But at least we know we’re able to get them through the larval phase.

Just for kicks, here are some pictures of where we grow the larvae and how we do the twice-weekly water changes.

Larval culturing paddle table. © Allison J. Gong
Larval culturing paddle table.
© Allison J. Gong
Step 1: We pour the larvae into a filter to concentrate them into a smaller volume of water. Then we can wash or rinse the jar. © Allison J. Gong
Step 1: We pour the larvae into a filter to concentrate them into a smaller volume of water. Then we can wash or rinse the jar.
© Allison J. Gong
Steps 2 and 3: We use a turkey baster to transfer most of the larvae from the filter into a jar of clean water. The final step is to turn the filter over and wash the last larvae into the jar. © Allison J. Gong
Steps 2 and 3: We use a turkey baster to transfer most of the larvae from the filter into a jar of clean water. The final step is to turn the filter over and wash the last larvae into the jar. Then we fill up the jar and resume the stirring.
© Allison J. Gong

An update on other matters:

Today is the six-month birthday of my baby urchins! Six months ago to the day these little guys were zygotes, and six-months-plus-one-day ago their parents were roaming the intertidal. They grow up so fast!

Juvenile sea urchin (Strongylocentrotus purpuratus), age 6 months. 20 July 2015. © Allison J. Gong
Juvenile sea urchin (Strongylocentrotus purpuratus), age 6 months
20 July 2015
© Allison J. Gong

And lastly, that little shmoo-type thing that I found in the plankton yesterday has revealed itself to be. . . an anemone!

One of the things I like best about cnidarians is the beautiful transparency of their bodies. I love how you can see fluid circulating through the tentacles. Gorgeous, isn’t it?

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