(Yet) Another Crustacean

Amphipod among Leopard Frog Eggs, 3/29/2021

The pinkish-tan creature in the photo above is an amphipod. Amphipods, like fairy shrimp, crayfish, seed shrimp (the very small creatures creating the snow globe effect in the leopard frog egg time-lapse video) and isopods, are crustaceans. Like the seed shrimp, this guy showed up along with some leopard frog eggs I was photographing -- you always get more than you bargain for in the wetland.  Honestly, I had never heard of amphipods (or isopods, for that matter) and had to look him up. According to my research, most amphipods, commonly known as "scuds," are ocean dwellers (thousands of species!) but there are also a respectable number of species that live in freshwater. 

Amphipods are detritivores, making their living on the dead plant and animal waste at the bottom of the wetland, but also possibly grazing a bit on algae. It's hard to know how the fellow above (and I don't actually know if that one is male or female) came along with the frog eggs -- if it had business with the eggs, the bit of algae that appears in the picture, or just got sucked into the container I was bringing them out to photograph with. (As always, the eggs and amphipod along with any other random critters in the container were returned to the pond after the photoshoot.)

You may notice the similarity between the names for "isopods" and "amphipods."  The "pod" portion comes from the Latin for foot; "iso" is Latin for "equal," and the name isopods refers to the fact that all isopod legs are essentially the same. In contrast, the name "amphipod" references two kinds of legs, the amphipod having two distinct types of legs with thoracic legs for climbing and walking and abdominal legs more suited to swimming. We only have the side view of our amphipod, but like fleas, they are quite flattened side to side when viewed from above or head-on.

With regard to surviving the dry months of the ephemeral wetland at Homer Lake, amphipods are able to burrow into the mud and wait out the dry spells as needed.

If you'd like to learn more about amphipods, I found the following webpage helpful: https://uwm.edu/field-station/scuds/

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