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Friday, November 29, 2013

Helmuts or Kisses?

We spent a little time tidepooling at Point Reyes this afternoon.  Eric came across a few clusters of snails that appeared to be laying eggs.  In the picture below, there are at least 5 snails on a blade of kelp.  The snails are surrounded by densely packed egg capsules.


The snail is a Variegated Amphissa (Amphissa versicolor).  [Unfortunately, this isn't a great example of this species because these individuals are covered by a bryozoan so their true shells are hidden.]  

Here's a close-up of the egg capsules on the right side:


From this angle you can see that the capsules are two-parted.  There's a rounded basal portion attached to the kelp, and an upright vertical section that looks like a very tall cap.  These capsules are sometimes described as helmut-shaped, but they often remind me of Hershey's Kisses!

The developing embryos are in the rounded basal portion.  You can see them when viewed from above (next image):


Eventually the embryos will hatch out as swimming larvae and will develop in the plankton for a while before returning to shore and undergoing metamorphosis into crawling juvenile snails.

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