As you can see, skeleton shrimp have taken the basic amphipod body plan and dialed all the features to “scary”.
Skeleton shrimp live only in saltwater, and mostly near the coast. They eat whatever they can get, which may include protists, detritus, worms, diatoms, and other crustacean larvae. Although some filter feed or scrape food into their mouths with their antennae, most are predators. Allegedly, they freeze and wait for suitable prey to come along, which they then ambush. How they manage to hold still for more than 5 seconds without getting into it with their next-door neighbor is hard for me to imagine.
In spite of their fiery temperments, they seem to be good mothers. Not only do their brood their young inside pouches, they also seem to take care of them until they are big enough to pick their own fights.
Caprellids are probably wildly under-described, like almost everything on Earth; one of the authors of the study on L. minusculus has described 62 new species in eight new genera in the last 10 years alone.
I leave you with another chance to spend a little time observing skeleton shrimp. Watch for the moms with babies near the end, and enjoy a few minutes of relaxing nature-tation watching these Ultimate Fighting Shrimp.
As you saw in the video, skeleton shrimp often cling to bryozoans, hydroids, or eelgrass by appendages called pereopods. Here’s a closer look at their interesting anatomy and their various pods and peds:
Caprellids are amphipods, small crustaceans that get their name from their variously shaped legs, in contrast to isopods like wood lice, whose legs are all alike. Unlike the caprellids, most of the other amphipods scavenge food or eat detritus. For comparison, here’s a representative amphipod.
Caprella linearis is a species of skeleton shrimp in the genus Caprella.[1] It is native to the North Atlantic, North Pacific, and the Arctic Ocean. It closely resembles Caprella septentrionalis with which it shares the same geographical distribution.[2][3]
Caprella linearis is the type species of the genus Caprella. It was first described by Carl Linnaeus in 1767 as “Cancer linearis“.[4]
The male C. linearis has a more elongated head than the two other species. Furthermore C. linearis has a pair of tubercles on the fifth body segment and a single on the sixth. The color may be red, green or light brown.
Habitat:
This amphipod does not seem to be very selective on its habitat. It can be found on any depth from the surface to several hundred meters, on algae, sea grass or often hydroids on greater depths.
Distribution:
This seem to be widespread species. It is registered in Arctic areas, the North Atlantic and Pacific Oceans, as well as in New Zealand.