Deep-blade

Here's a fun mystery close-up — an extreme view taken through a microscope.  Can you guess what type of animal this might be?
 

 

I'll zoom out a bit more:

 

And now I'll show the entire animal, so be prepared for the answer below!  

First, a few more hints: This is a crustacean that can be found in the low rocky intertidal zone and subtidal areas, but it's relatively small and can be quite cryptic.  [In the photos above, the small, colorful patches are chromatophores which play a role in camouflage.] 

Hmmm.  On second thought, I've change my mind — here's one more close-up before I give the answer away.  (Although this photo will probably help a lot!)

 

Isn't that a spectacular tail?

Okay, now here's the entire animal:

 

Meet Spirontocaris prionota, commonly known as a Deep-blade Shrimp.  This is the first time we've encountered one on Bodega Head.  I was impressed with the details and colors when viewed under high magnification.

The "deep-blade" portion of the name refers to the distinctive rostrum — the portion of the carapace that projects forward in front of and above the eyes.  It's extremely narrow (like a knife), and impressively serrated above (see first two photos).

To orient you to this shrimp's anatomy, the next image shows the same photo with a few labels:

 

Apparently, not much is known about the biology of this species.  Here's one more image — a head-on view emphasizing how well camouflaged this shrimp would be among the rocks and sand.  And note some of the other intriguing features.  For example, what do they do with those small front appendages tipped with noticeable black spines?  Why do they have clusters of long setae (bristles) on their legs?