May 19, 2022

According to the rangers at Wupatki National Monument, hundreds of odd, prehistoric-looking critters surfaced and began swimming around a temporary lake in the desert after a heavy summer downpour in northern Arizona.

Triops are tadpole-sized critters that “look like little mini-horseshoe crabs with three eyes,” according to Lauren Carter, Lead Ranger at Wupatki National Monument. According to Central Michigan University, their eggs can remain latent in the desert for decades until sufficient rainfall falls to create lakes that provide habitat and time for hatchlings to mature and deposit eggs for the next generation.

Triops are so rare that when travelers reported sighting them at a temporary, rain-filled lake within the monument’s ceremonial ball court, a circular walled structure measuring 105 feet in diameter, the monument’s employees were perplexed.

Following a late July monsoon, “We knew that there was water in the ball court, but we weren’t expecting anything living in it,” Carter said. “Then a visitor came up and said, ‘Hey, you have tadpoles down in your ballcourt.'”

Carter initially wondered if toads, hibernating underground during the dry season, had emerged to lay eggs during the wet spell. She traveled to the ballcourt to conduct an investigation.

“I just scooped it up with my hand and looked at it and was like, ‘What is that?’ I had no idea,” Carter said. But then, she felt an inkling of familiarity; Carter had previously worked at Petrified Forest National Park in northeastern Arizona, and recalled reports of Triops there. “And then I had to look it up,” she explained.

According to Central Michigan University, Triops — Greek for “three eyes” — are occasionally referred to as “dinosaur shrimp” due to their lengthy evolutionary history; their ancestors evolved 419 million to 359 million years ago.

Triops can reach a length of 1.5 inches after hatching. They feature two huge compound eyes with a black rim, similar to a dragonfly or bee, and a small ocellus, or simple eye, in between.

The Triops at Wupatki National Monument were fortunate to experience a brief but heavy rainstorm. During this period, the Triops’ eggs hatched and, within hours, the tiny crustaceans began filter feeding. Triops live up to 90 days, but Carter estimated that the pond beside the ball court lasted about three to four weeks.