Tasmania – Lawn Shrimp
These were also found in the blueberry patch mulch (bark and pine needles on top of sheets of newspaper). They were pretty tiny, as you can see by comparing them with my fingertip:
They were about the size and approximate shape of a flea, and could jump a couple of inches, but they weren’t fleas.
They were actually little crustaceans that have taken to living on land, kind of like woodlice have done.
But, unlike woodlice (which are isopod crustaceans), these are amphipods, probably in the family Talitridae. And while they look very shrimpy, they are not in fact shrimp, which are in a different crustacean family altogether. They are actually much more closely related to the Gammarus amphipods that we have living in our little stream here in Michigan.
They get different common names, depending on where they are found – they are “beach hoppers” on the beach, “lawn shrimp” on the lawn, “sand fleas” in other sandy areas, and “landhoppers” when they are just found somewhere generic. Since they are crustaceans, which breathe using gills, they only live in very moist environments where their gills won’t dry out.
According to Bug Guide, the species Arcitalitrus sylvaticus is originally from southeastern Australia (which includes Tasmania), so that might actually be what these are. Even though they aren’t a native North American species, they get into Bug Guide because they have been unintentionally introduced in Florida and California. So Australia can produce invasive species, too!
Their hopping ability is kind of unusual for a crustacean, probably because most crustaceans are aquatic, and hopping doesn’t work very well underwater. They can’t jump nearly as far as most jumping insects, but they can jump well enough to frequently jump into pet-water dishes outdoors, to the puzzlement of the pet owners.
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So those are sand fleas? Way cool!