At home in the sand

 

We noticed this small (~5 mm across) sea anemone in the low intertidal zone in Pacific Grove this weekend.  When I zoomed in on the photo on the camera, I realized it wasn't a species I was familiar with.  Later on, after doing a little research, I eventually figured out that this is Cactosoma arenaria — a new species of sea anemone for us!

There are a couple of things to notice about this speciecs.  As mentioned, it's small — typical height is only ~2 cm.  Look for the alternating brown and white bands on the tentacles (they generally have 24 tentacles).  Some of the bands are V-shaped (especially in the last photo of this post, below).  Also look for the brown cuticular sheath on the column (the lower portion of the anemone, see photo above).  The sheath includes embedded sand grains and shell fragments.

 

Cactosoma arenaria can be found around kelp holdfasts, and also among sand-encrusted tunicates (or sea squirts) in the low intertidal zone, which is where we observed these.  The species name, "arenaria", refers to sand.

 

This is a southern species, with known occurrences from about Monterey to San Pedro, CA.  So we're not likely to see it in Bodega Bay, but if you're in Central or Southern California, keep your eyes open for this little beauty.