The Story of the "Tadpole Shrimp"

The Story of the "Tadpole Shrimp"



Being a bored preteen child and having been tortured by having the luxury of being forced to grow up in the the lower confines of the Llano Estacado or the upper regions of this great Chihuahuan Desert in a place called Midland, Texas, (Once called the home of nothing to do) there was not a heck of a lot to do in the blistering 100 degree plus days of summer. One Summer along about 1972 or 1973, I am not real sure as to when, and it really does not matter. I was bored and looking for something to do so I had got a hold of the kids that lived down the street and we had decided to take a journey to a place that we all called the "Caliche Pits". It was about 2 miles and our only transportation was to walk.....

After getting some canteens with filled and some grub as we called it for food, we set off and spent the better part of the day there as I recollect all these years later... It had rained and there were lots of small shallow pools of water only about 6 to 7 inches deep... I remember seeing them filled to the brim with tadpoles.

We wanted to catch some and bring them home, so we scooped them up and we noticed that there was some strange looking things swimming around in the water with the normal everyday common tadpoles. These things had a hard shell and a long tail with whiskers on the end and a million legs that they used in a swishing motion to move through the water.... Gee there must have been a thousand of them there. The water in the pools was a complete frenzy of these new discoveries and the tadpoles.

I am not sure how we transported them from the pools to my parents house, but non the less we got them there. I had an old aquarium that we used to put these things. They did not survive very long in the aquariums. It probably had something to do with not getting enough oxygen or something like that.

My dad had come home from work and we showed him our new discoveries..... I remember very clearly the look on his face when he said " I think you have just discovered a Trilobite!" and I said "What's a Trilobite?" He said that they had been extinct for millions of years and only fossils remained today and that we would all be very famous if it was a Trilobite. He contacted a friend who worked as a biologist or palaeontologist for the Shell Oil Company and he came by to look at these little creatures. He said that he did not know and that he would contact a friend at The National Geographic Society. The man from National Geographic Society did some research after being sent a photograph and determined they were either "Fairy Shrimp" or "Tadpole Shrimp" Years later we discovered the were in fact "Tadpole Shrimp".


Below is information taken from October 1975 National Geographic Society story about them...

It says the microscopic eggs can remain dormant for a season or for hundreds if not millions of years, and can survive temperatures of extremes of over 124 degrees F and below zero, the eggs are strewn with the wind and will hatch only after a certain amount of water pressure is present thus ensuring a new generation lives on, but not all eggs will hatch every time.

The desert shrimp as the are called live in the potholes of Utah's, Canyon Lands region.... Later new discoveries have been found in the country of Iraq and of all places, Midland, Texas.

Funny now some 27 years later I live just 3 to 4 blocks from the old "Caliche Pits", and I have often wanted to go there in search of these amazing "Tadpole Shrimp"!


Bill Bentley
November 28, 1999



tadpole shrimp
Triops sp.
Well adapted to life in the desert, these crustaceans live in temporary rainpools which form in low lying
areas during the summer monsoons. Hatching from eggs which have lain dormant in the soil, they
mature quickly feeding on detritus washed into the pool, mate, and deposit their eggs before the pool
dries up.


Anteriodorsal view of a desert pool tadpole shrimp, out of water.

Anteriodorsal view of a vernal pool tadpole shrimp, out of water.
A "Living Fossil" in the
West Texas Desert Area?
What is a Living Fossil?

Quick!! How many "living fossils" can you name? Would you believe that there is a "living fossil" right here in the arid deserts of West Texas? Tadpole shrimp (Lepidurus packardi), a freshwater crustacean "living fossil." The desert pool tadpole shrimp derives its name from looking somewhat like a frog or toad tadpole at first glance, and from being found only in "desert" pools (temporary springtime pools). Now you ask, exactly what is a "living fossil?"

A living fossil is an organism living today that appears to be identical to specimens in the fossil record. The most famous example is probably the coelacanth (Latimeria chalumnae), a primitive, lobe-finned fish from the Cretaceous Period. Coelacanths were known only from their abundant fossils until a live coelacanth was recovered by a deep-sea trawler in the Indian Ocean in 1938. This fish still lives in the ocean depths, virtually unchanged from its fossil ancestors of approximately 70 million years ago.

A ventral view of a desert pool tadpole shrimp, note the paired phyllopods, paired  ventral antennae segmented abdomen and orange egg sac.

A ventral view of a desert pool tadpole shrimp, note the paired phyllopods, paired ventral antennae segmented abdomen and orange egg sac.

Tadpole shrimp are considered living fossils because their basic body characteristics have remained the same for millions of years. General characteristics of tadpole shrimp include a shield-like carapace (shell), a fused pair of eyes on top of the carapace, a segmented abdomen, and paired tail filaments. Tadpole shrimp also have paired ventral appendages called phyllopods (phyllo = "leaf" and pod = "feet"), which beat in a wavelike motion from front to back and act as propulsion for the animal. At the base of these paired phyllopods is a ventral midline food groove, which effectively funnels microscopic food particles up to the animalís mouth. This basic design appears to be well-adapted to the desert pool environment, since these basic body characteristics have remained unchanged over time.

Tadpole shrimp belong to either the genus Triops or the genus Lepidurus. The tadpole shrimp in the genus Lepidurus have a paddle-shaped flap between the tail filaments, which shrimp in the genus Triops do not.

Differences in size and body shape in desert pool tadpole shrimp taken from the same pool in one dipnet.

Differences in size and body shape in desert pool tadpole shrimp taken from the same pool in one dipnet.


From: John Regan
To: webmaster@caver.net
Sent: Tuesday, December 13, 2011 3:18 PM
Subject: Tadpole Shrimp
Hello Bill,

I just came across your fine article on Tadpole Shrimp while doing some research on the fascinating little guys. I thought you might be interested to know that I found them in Afghanistan, too. Although it was not in a particularly dry region (just outside of Kabul) they were in a temporary pool that I had visited many times. I did not notice them until the creed nearly dried up, and suddenly there seemed to be a bunch of them. I had never seen tadpole shrimp before and I was stunned to see what looked like a freshwater horseshoe crab.

HOOAH
Jack
Northwest Wildlife Online

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