Sunday, November 21, 2021

Anemone addendum

Okay, last night I shared a couple of photos of Ten-tentacled Sea Anemones (Halcampa decemtentaculata).  There's lots to be intrigued about with this species.  One of the notable things is the variation in color patterning.  

Below are a few more examples interesting patterns sometimes show up on the oral disc (like flowers or snowflakes); occasionally there's a beautiful maroon color on the disc or the tentacles; other individuals we found were brownish overall but nearly transparent:

 
 
 
 
 
Having such variable color patterning might help to thwart predators, making it harder for them to develop a search image for a consistent color form.  [For another example of this in brittle stars, see the post called "Colorful discs" from 1 October 2016.]
 
One of the more notable color forms had a remarkable combination of white, gray, and brown patterning which made it look like bits of shell or other debris mixed in with the gravel on the bottom of the tidepool.  (We started calling this form the "moustache-type" since the dark bar across the white on the central disk looked like a moustache.)  It's hard to tell that this is a sea anemone, especially from a distance, because the overall anemone shape is disrupted by the color pattern.  It was very effective!  [You can click on the image for a larger version.]


 
For the record, Eric's sharp eyes also spotted a few tiny juveniles (less than 5 mm across):
 
 
We hope you enjoyed this introduction to Halcampa!  [Another fun fact: This anemone was first described by Cadet Hand, the founding director of the Bodega Marine Laboratory, back in 1954.]
 
P.S.  I know some of you will be wondering those purple bits in the background of some of these images are sea urchin spines.
 

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