Three-Eyed "Dinosaur Shrimp" Make A Surprise Appearance In Arizona Following Monsoon

Their dry eggs can lay in wait for decades, only hatching when things get wet. Image credit: Irina K /

Jumanji fans will remember the dramatic scene in which a monsoon delivers a slurry of crocodiles to Robin Williams’ living room, a stretch for reality but nonetheless, these weather systems can trigger the arrival of unexpected visitors. Arizona recently received one such delivery as a temporary lake that sprung up during heavy rains became filled with bizarre, three-eyed beasties. According to officials at Wupatki National Monument, they’re called triops, and their metamorphosis into prehistoric-looking tadpoles can occur decades after the eggs have been laid.

Following the monsoon, staff at the WNM were none the wiser as to the arrival of any alien-looking tadpoles but were alerted by tourists to a colony of mystery animals that had taken up residence in the site’s ceremonial ball court. Curious as to who had moved in, they investigated, suspecting that some toads may have optimized on the wet weather and released some eggs.

"We knew that there was water in the ball court, but we weren't expecting anything living in it," said lead interpretation ranger at Wupatki National Monument Lauren Carter to Live Science. "I just scooped it up with my hand and looked at it and was like 'What is that?' I had no idea.”

Some quick research revealed the pool crashers to be a colony of triops, potentially the species Triops longicaudatus though tests are needed to confirm. They’re also known as tadpole shrimp or – our personal favorite – dinosaur shrimp, owing to the ancient features they’ve retained from their ancestors that lived hundreds of millions of years ago.

While triop is Greek for “three eyes”, their setup is a little more complicated than that. They have two main eyes with black rims, between which sits a pit organ. This "third eye" is common among insects and comes in handy for prey animals as they can detect changes in light, such as the shadow of a bird closing in on you.

A bit like the sea monkeys you can buy in toy stores, the dinosaur shrimp eggs can remain dried out in suspended animation while they wait for the optimum conditions in which to hatch, and what are those? A butt load of rain.

Once wetter than wet, the eggs can hatch after decades in wait and release little dinosaur shrimp that resemble three-eyed horseshoe crabs. This explains how the triops at the WNM were able to sprout seemingly out of nowhere and make the ball court their home, emerging in their hundreds much to the surprise of staff and visitors.

While an established crew estimated to be several hundred members strong, the triops didn’t last long. These animals have a lifespan of around 50 to 90 days, but this was hampered by hungry birds and warm weather which saw the pool dry up again in just a few weeks.

Triops are hermaphrodites but they’re also capable of sexual reproduction, though this is thought to be a rarer means of making babies for the species. Exactly how many eggs the triops managed to squeeze out during their short jaunt in the ball court is, for now, a mystery, but all will be revealed in the next monsoon.

[H/T: Live Science]


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