Featured image courtesy of: Melbourne Briscoe.
AKA: Giant skeleton shrimp, caprellid amphipod, phantom shrimp.
The first time I saw a skeleton shrimp, I could have sworn I was looking at an alien. Rising, up and down, like a miniature praying mantis, this one was hooked to a diver’s BCD. The diver pointed it out and asked me what it was. I stared at it. I had never seen anything like it. It was so small, barely bigger than my fingernail and as thin as a needle. If it hadn’t been for its writhing, I would have assumed it a stray piece of sea grass.
“I have no idea,” I said, and stepped aside to ask an instructor. She didn’t know either. Internally I cursed myself for not bringing my identification book, “Marine Life of the Pacific Northwest.”
That was around the time I was starting to put a concerted effort into identifying the things I was seeing.
When I got home I began paging carefully through the book, marking out the things I had seen that weekend in the Hood Canal, new latinate names awkwardly crossing my tongue. And then, there it was, half way through the book, nestled into the section on invertebrates, among all the really tiny critters. An Alaskan Skeleton Shrimp.
The blurb read: “The Alaskan skeleton shrimp is one of the largest and most obvious of numerous, very similar species. Sometimes they ‘hook’ themselves on the neoprene suits of scuba divers. Although usually unnoticed, they are abundant. Over a dozen other smaller, very similar species live in the Pacific Northwest.”
Yup, that was it, a Skeleton Shrimp. It might not be the Alaskan Skeleton Shrimp, but it looked exactly like the picture in the book. And, we had found it in the right range.
In pursuit of more information, I discovered they are often found amongst eelgrass, hydroids and bryozoans in the intertidal to subtidal range. This made sense as much of our dive site’s shallow areas were rich in eelgrass.
I also learned that they are indeed often called “praying mantis of the sea.” Like the praying mantis female, after mating the female skeleton shrimp will also kill the male. She’ll do it though by injecting venom from a claw within her gnathopod, those two very tiny front legs just below her antennae.
They eat pretty much anything and are typically the prey of nudibranchs, shrimp, surf perch, jellyfish, and brooding anemones.
Here’s a great picture of the anatomy of a skeleton shrimp: