Desert Tadpole Shrimp and Clam Shrimp

It’s July 29, 2021, and we’ve had pretty good monsoons here in Southwestern Colorado. The water often brings interesting creatures out of hiding, as they try to breed before the moisture disappears.  And so, with a heart full of hope and  a desert full of water, my Trusty Hound and I went out into the Canyons of the Ancients  to see what we could see.

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We came across a small puddle in the bottom of a cattle tank. It had been bone-dry  just a few weeks previously. Was there anything in it? We got out of the jeep to have a look.

Ephemeral pool in the Canyons of the Ancients.

There were tiny ripples on the surface of the water, although there was no wind. As I looked closer, I saw that the ripples were caused by small Tadpole Shrimp swimming just below the water surface. They were colored orange-red against the murky, tea colored water, presumably because of hemoglobin in their gills.

Tadpole Shrimp swims just under the surface of the water. The gills show red against the murky water.

We needed a specimen for a closer look. Jack leapt into action!

Jack the Troll is very helpful during freshwater invertebrates surveys.

Honestly,  this sort of behavior is why I can’t have nice things.

Fortunately, Jack has provided a sense of scale in the photos, showing the size and shallow depth of the pool.

Jack bravely demonstrates that the pool is quite shallow.

I swept a dip net through the water, and emptied the contents into a black rubber bowl.

There were numerous small Tadpole Shrimp, perhaps a half to three-quarters of an inch long. There were also (real) tadpoles in with the Shrimp. And there were some other small invertebrates.

Two Tadpole Shrimp, one Tadpole and numerous Conchostraca

At the time, I could not see well enough to tell what the small inverts were. I assumed that they were Fairy Shrimp. When I examined my photos later, though, I saw that the invertebrates were actually Clam Shrimps - Conchostraca spp.

I’ve never seen Conchostraca before. I wish I’d spent more time and gotten better photos of them.

More tightly cropped image, showing small Tadpole Shrimp and numerous smaller Conchostraca.

Tadpoles, Chonchostraca and Tadpole Shrimp

Tadpole Shrimp and Tadpole

I’ve not keyed them out, but I suspect that the (real) tadpoles are Spadefoot Toad tadpoles.

Closeup of two of the Tadpoles. They seemed to glow golden in the bright sunlight.

The tadpoles sparkled  a bright golden color against the black of the plastic bowl in the bright sunlight.

All in all, a marvelous trip. I hope I can get back out there before the pool dries so that I can get better photos of the Conchostraca…