Against the grains

 

 

Okay, so this post is a follow-up to last night's photo.  This shrimp is a master of camouflage, but here are a couple of photos (above and below) where it might be a little easier to see them because they're on the surface of the sand.

 

 

We've learned the pair of white spots just in front of the tail (on the 5th abdominal segment) are consistent enough that you can use them to locate the shrimp and orient to its tail and head ends.  Sometimes the white spots are merged into the shape of a heart.

 

The shrimp's coloration is remarkable — they match the sizes and colors of the surrounding sand grains and shell pieces so well that even when the shrimp was right in front of us it was often hard to see it.  The next two photos are a little more challenging, but I'm guessing you'll find the shrimp!  (Hint: You can also look for the narrow white stripes on the legs.)

 

 

 

 

 

We think this beautiful shrimp is Crangon handi, although we had to look more closely at several features to work through the identification (and see note at bottom of this post).  Some of these characteristics are hard to see in the field, but because we've noticed there aren't many Crangon handi photos online, Eric made this really useful guide to point out some important features (see below). 

 

Note the shape of the antennal scale, the shape of the claw on the cheliped (fancy name for a leg that bears a claw), and the three tiny spines that flank each side of the very tip of the tail (telson):

 

 

Drawings modified from Kuris, A.M. and J.T. Carlton (1977). Description of a new species, Crangon handi, and new genus, Lissocrangon, of crangonid shrimps (Crustacea: Carida) from the California coast, with notes on adaptation in body shape and coloration.  Biological Bulletin 153: 540-559.

 

We found these shrimp in small patches of open sand between rocks in the intertidal zone.  Although the shrimp are so well camouflaged that we've probably walked by them many times without noticing them!

 

I can't help showing a few close-ups so you can appreciate how well they match the sand.  One of the anterior end (with two rounded pearly eyes), one of the tail, and a close-up of the pigment spots called chromatophores (there are also some actual sand grains on the shrimp):

 

 

 

 

 

 

 

P.S.  I showed a photo of Crangon handi from a more wave-exposed site back in June — see "Perfect match" on 23 June 2023.  Note that the larger color patches on that shrimp match the coarser grains on the outer coast.

 

P.P.S.  There are a few things about these shrimp that stray from the original description — e.g., we found them on finer-grained sand and their color patterning is finer.  However, we noticed a photo in Jensen's Crabs and Shrimps of the Pacific Coast (2014) that shows Crangon handi with similar patterning to the shrimps we photographed.  But if you have thoughts about this identification, let us know!  We're interested and open to looking further at any defining traits for this species.