Photobombed by a shrimp!

So I was trying to photograph a Short-spined Sea Star (Pisaster brevispinus)...when a shrimp came shooting across my field of view:

 

I looked up from the camera, and then noticed another shrimp off to the right.  This one featured a bold white and green color pattern:

 

And then I saw a third shrimp a little further away, in beautiful claret with a central dorsal stripe:

 

And then yet another, in mottled grays and salmon pink:

 

I believe these shrimp are all the same species, just an amazingly variable one!

Sadly, identifying shrimp is a weakness of mine.  But I love looking at them and hope to learn more about the local species some day.  Feel free to contact me if you know which species this might be.  (I'm guessing it's a species of Heptacarpus.)  These shrimp were in a shallow sandy tidepool in an intertidal boulder field at Pinnacle Gulch.

P.S.  If you're unfamiliar with the term "photobomb" — it means "to spoil a photograph of (a person or thing) by unexpectedly appearing in the camera’s field of view as the picture is taken, typically as a prank or practical joke." (definition from oxforddictionaries.com)