Tadpole Shrimp, A Living Fossil

A recent trip to Utah included a stop at Dead Horse Point State Park where I took a short hike along the canyon rim to an area of potholes.

Recent storms had filled the potholes with water, just a few feet from the edge of the cliff 2000 feet above the canyon floor.

I saw movement in a few of the pools and when I looked closely, saw tiny creatures crawling and swimming in the puddles.  A park ranger later identified them as Tadpole Shrimp from my photo.  They have often been called "living fossils" because they are essentially unchanged from their 250 million year-old ancestors.  These fascinating animals live just 20 or 30 days in ephemeral pools.  They have been known to lay eggs that stay dormant for years until rain fills the puddles long enough for them to hatch.

This photo shows how close to the drop-off some of these potholes were.
Tadpole Shrimp (scientific name Triops longicaudatus, in the order Notostraca. in the class Branchiopoda) are sometimes sold in novelty stores, but it was a thrill to find them in the wild.