Fairy Shrimp at the Colorado National Monument

Temporary pool at top of cliff, showing the pour-point outlet

When I was visiting the Colorado National Monument recently, I came across a small pool of water at the top of one of the cliffs. The pool was perhaps three feet across, and only a couple of inches deep. This was the only water I saw while visiting the Monument.

If the pool ever managed to get a few inches deep, there was an eroded pour-point that would dump the water down the face of the cliff.

And inside this pool, at the edge of the cliff, were Fairy Shrimp.

These little creatures are similar to Tadpole Shrimp, in that they are both Brachiopod crustaceans that live in temporary desert pools. Both creatures lay eggs than survive decades of desiccation while still remaining viable.

Here’s a brief cellphone video of some of the shrimp:

Fairy Shrimp are much smaller than adult Tadpole Shrimp, and look more like ‘real’ shrimp. I think that Tadpole Shrimp always look more like Horseshoe Crabs.  Fairy Shrimp are one of the (many) things Tadpole Shrimp like to eat.

I only had my cellphone camera with me, so could not get better close-ups of the shrimp. I do have an older photo of a Fairy Shrimp from a pool in Cortez.

Fairy Shrimp, Cortez, CO. The round, greenish objects are eggs.

What I found to be most amazing about finding these guys was how tenuous their existence must be.

Too dry, and their pool would evaporate. The adults would die, and the eggs would stay dormant until future rains.

A little bit too wet, their pool would start to vent excess water, and possibly shrimp, down the face of the cliff.

Something of a balancing act.