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Tuesday, December 31, 2013

Plus two

Okay, so I have a soft spot for sea stars...and for learning new things!  And I'm thankful that each day offers an opportunity for a new natural history sighting.

Remember the small Sunflower Star (Pycnopodia helianthoides) with eight arms?  (Review the post from 17 December.)  I mentioned that Sunflower Stars start out with 5 arms, add a 6th, and then continue adding arms in pairs adjacent to the newest arms until they end up with 20 arms (or more).

Today I found my first 10-armed Sunflower Star.  It was very small, only ~2 cm across, but offered a chance to see the addition of the next two arms.


In the picture above, arm 6 is at 1 o'clock, arms 7 and 8 are at 12 and 3 o'clock, and arms 9 and 10, the newest additions, are the smallest arms just outside of 7 and 8.  What fun to see this process in action!

Here's wishing for many exciting natural history observations for everyone in 2014!

Happy New Year!


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