Dividing

 

During field surveys last week, I noticed this very elongated sea anemone.  It took a few seconds for me to register that this Moonglow Anemone (Anthopleura artemisia) might be dividing, and I wasn't sure that I'd seen this species dividing before.  (It's known that Moonglow Sea Anemones can undergo fission, but I'm not sure I've seen it myself.)  So I thought it would be worth posting a photo for the record.

In the Bodega Bay area, the anemone best known for undergoing longitudinal fission (basically dividing into two) is the Aggregating Sea Anemone (Anthopleura elegantissima).  One individual begins to stretch out, then eventually divides in half, regenerates a few internal structures, and becomes two genetically identical individuals (clones).  The process is illustrated below.  The right column shows the external view of a dividing anemone, and the left column shows the internal view:

 

Modified from Sebens, K.  1983.  Morphological variability during longitudinal fission of the intertidal sea anemone, Anthopleura elegantissima (Brandt).  Pacific Science 47: 121-132.

In case you're curious to see what this looks like (and if you want to watch for it yourself), here are older photos of Aggregating Sea Anemones in the process of dividing:

 

 

(Don't worry about the yellowish color of the anemone above; they're pale when they're growing in very shaded environments.)

Maybe next time we go back to the field site where the first photo was taken we'll see two Moonglow Sea Anemones in the little pool!  Stay tuned...