Critters: The tadpole shrimp, a blast from the past in present-day Mesa County |

Critters: The tadpole shrimp, a blast from the past in present-day Mesa County

A close-up photo of a long-tailed tadpole shrimp.
David Leatherman |

Editor’s note: “Critters” is a monthly series featuring insects, spiders, snakes and other freaky/fun creatures unique to the Grand Valley. You know, the kinds of critters you aim to keep your distance from but love to learn about. Have a critter you want discussed? Email

When Anniel Littlejohn’s youngest son discovered numerous long-tailed tadpole shrimp (Triops longicaudatus) in the pond on their Glade Park property this past July, she was surely surprised to see them living in nature.

“He said the pond was full of tadpoles, but I went and looked and said, ‘Nope!’ They weren’t tadpoles; they’re something else,” Littlejohn said. “They sell these things at Hobby Lobby, and I had raised them before so I was familiar with them. I had never seen them in the wild before though.”

Since July, the shrimp in the pond disappeared once, then Littlejohn said they returned again after the recent rains. She presently has them swimming in her “little pond used to catch run-off water.”

“Now we have more of them, but this time they’re bigger,” she explained.

Tadpole shrimp have a short lifespan — think two weeks or so — and these odd-looking crustacea grow to about two inches long.

According to a Colorado State University Extension fact sheet, “The long-tailed tadpole shrimp is a resident of small, very temporary (vernal) pools that form after heavy rainfall or flash floods. Flooding that covers the dormant eggs cause them to hatch and the tadpole shrimp begin to feed and grow. They are omnivores that will consume algae, organic particles that they stir up from the bottom and guide into their mouth. They may also prey upon small arthropods (including mosquito larvae), worms and anything they can capture and subdue; they may also be cannibalistic.”

The fact sheet also mentioned that tadpole shrimp are sold, as Littlejohn said, “as the item of aquarium kits under the trade names ‘Aquasaurs’ or ‘Triassic Triops.’”

“They look like prehistoric crustaceans,” Colorado State University Extension Entomologist Bob Hammon said. The shrimp appear to be “from the fossil record, like they should have been around in the time of dinosaurs.”

Another fun fact: Most long-tailed tadpole shrimp are hermaphrodites, meaning they have both the male and female sex organs and are capable of self-fertilization.

“There aren’t any female-only shrimp, but there are some male-only,” Hammon added.

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