Correction: A previous version of this story incorrectly referred to these creatures as hexapods from the springtail family with internal mouthparts. They are crustaceans with external mouthparts. It also incorrectly stated they can use their tails to spring away from predators.
In summer 2023 what seemed like tiny aliens turned up at the Wupatki National Monument. A visitor told park staff that tadpoles were wriggling about in a pool of standing water that had flooded the Ancestral Puebloan ballcourt.
With almost record-breaking winter snow then spring melt, followed by healthy monsoon rains, park staff thought some toad tadpoles had hatched.
But when a ranger went to investigate, she had a surprise. The one- to two-inch long creatures resembled tiny pink horseshoe crabs. They were Triops – sometimes called ‘dinosaur shrimp’ or living fossils, because they show few differences from specimens found in rocks dating back as far as the Cambrian period, almost 500 million years ago.
Primitive crustaceans known as Branchiopods, Triops have three eyes and ribbed tails ending in two prongs, called ‘furcula’. They’re in the same biological group as fairy shrimp, and breathe through gills on their many legs.
Cruising along the bottom of ponds, they use appendages on those legs to make a tiny current which brings fresh, oxygen-rich water to their gills and small particles of organic debris to their mouthparts.
Incredibly, Triops eggs can remain dormant for decades in dry desert soils. When enough rain falls to form temporary ponds, some of the eggs hatch. Then they race to reach adulthood, breed, and lay more eggs … before the pond dries out. Extremely resistant to freezing and drying, those eggs are left behind to wait for the next wet summer.
This Earth Note was written by Diane Hope and produced by KNAU and the Sustainable Communities Program at Northern Arizona University.
