What is a Mantis Shrimp?

We've spotted a new critter in the canal. 

Movement in the edge of the water caught my eye but I had no idea what I was seeing. It looked sort of like a shrimp, but kinda like a lobster. It was mostly brownish gray, but also had some blue on it and it scurried across the bottom of the canal foraging as it went along. I grabbed my camera and got this video.
 

I now know what I was seeing was a Mantis Shrimp. I called Thomas over and he knew what it was. There are many types of mantis shrimp, but I'm pretty sure this is Squilla empusa.

Watching the video, you can see how it jumped as it entered the shadow. And now that we've seen another one (maybe the same one) I noticed they always hesitate when moving from lighted areas to shadows and vice versa. Maybe it's a danger signal for the mantis shrimp. There's an extensive section over at Wikipedia about their eyes which are "the most complex eyes in the animal kingdom." I also learned that these little critters are known as "thumb splitters" because they can lacerate fingers. I won't be attempting to handle any of these! 

- Paige