By ABF Education Coordinator Ashley Kvitek
My drive in to work yesterday was ominous- dark clouds shrouded Indian Head and the humidity was hanging over the valley at a fairly unpleasant 78%. It’s another round of “will it or won’t it” down here in Anza-Borrego and although I’m not convinced it will rain, the mere hint of a promise of rain is enough to get most of us desert dwellers excited. Not only do rains bring with them the promise of leafy ocotillos and the unspoken possibility of flowers, there’s also a chance that the dry lakes and depressions will fill with water for just long enough to make things interesting in their murky depths.
|Clark Dry Lake, 2010. Photo by Jason Duke|
Let’s talk about those dry lakes (where fairy shrimp make their home) for a minute. I’ve never come across them in my travels in the more temperate climes, so when I saw Clark Dry Lake on a map I thought to myself, “Oh, it used to be a lake a really long time ago but isn’t anymore. Cool.” But that’s not it. Dry lakes didn’t just used to be lakes, they often are ephemeral, or temporarily filled. When the rains come through our desert region, the water pools in these low lying areas and voila! All of a sudden, and for a short period of time, you can have a lake in the middle of the desert, filled with all kinds of cool little critters to look at and learn about. The most fascinating to me are the fairy shrimp.
The first time I experienced the monsoon rains here in Anza-Borrego, people started talking about the fairy shrimp. I didn’t think much of it, assuming this was just a strange name for a desert creature. Which, to be honest, is true. Unfortunately, by the time I got around to asking what everyone was talking about, it was too late and my chance to see them had come and gone almost as quickly as the monsoon rains.
|Tadpole Shrimp, 2014.|
This August, I finally got my chance! When the rains came through, I paid attention. One day, Ranger Steve came in to the office with a few dead shrimp from out at the Ocotillo Wells airport. What a delight! I got the chance to get up close and personal with one species in particular, the tadpole shrimp (Triops newberryi). I’ll spare you the details of my poking and prodding, just know that they are a wonderfully strange looking creature!
I made a note to get myself out to Ocotillo Wells to see them alive and in person before they faded away again. Luckily, our rangers here are pretty spectacular and don’t mind having ABF staff tag along to learn a little something new once in a while, so I actually got to head out with my own science-loving tour guide for a living look at whatever we could find in the tire ruts left from the OHVs.
|Clam & Tadpole Shrimp, 2014. Photo by Steve Bier.|
And oh my goodness did we find some cool stuff! I saw all three of the different kinds of shrimp found in dry lakes and depressions of the Anza-Borrego region- fairy shrimp, clam shrimp, and tadpole shrimp.
Here’s where we get a tiny bit technical. Not all the shrimp in Anza-Borrego are fairy shrimp, even though many of us lay people use that as a blanket term. Research done by Marie Simovich and Michael Fugate in 1992 found five different species of shrimp in the three categories I listed above. I’ll list the Latin names for those inclined for deeper research, but will brush over the minutiae of the differences for sake of time. There are two different species of fairy shrimp- Branchinecta lindahli and Thamnocephalus platyurus; two different species of clam shrimp- Eocyzicus digueti and Eulimnadia texana; and one species of tadpole shrimp- the Triops newberryi that I got the chance to poke and prod.
|Fairy Shrimp, 2010. Photo by Jason Duke.|
They are all relatively small, two out of three were no bigger than my first finger. The tadpole shrimp were easy to see because they are bigger, move around a lot, and are not translucent. Just looking at the surface of the pools, you can see them swimming around. They’ve got these slightly strange eyes- two sets of two eyes- that ride on top of their body, slightly facing forward. And the underside of their bodies look much different than I expected- they have legs! They spend all their time in the water, but they have legs to dig holes to hide themselves with the displaced sediment when they see shadows overlooking the water or notice some other predator. The clam shrimp were harder to see, and I mostly saw dead ones, although Ranger Steve saw some live ones. When they are dried up on the edges of the water, they look just like dried up clams you might see out at the coast, just much much smaller and a darker color. The fairy shrimp are of a fancier nature. They are lacy and delicate, almost like their appendages used to be one fluid structure that was shredded at some point. Their translucent bodies allow us to see into their brood pouch to the individual eggs she is holding. Ranger Steve went back out about a week after we were there and found the tadpole shrimp were eating the fairy shrimp and the tadpole shrimp had become much larger than when I had seen them.
|Tadpole Shrimp, 2014.|
Extremely generally speaking, life cycles of our shrimp here in Anza-Borrego are rapid and fleeting. When the correct combination of rain, temperature, pH, and a slew of other things are present in a depression such as a dry lake or even a tire rut, the shrimp will hatch and begin a rapid maturation process to reproduction. All three of our different kinds of shrimp have different reproduction processes, but one thing remains the same- their offspring (in the form of eggs, generally speaking) can go dormant if their environment is not suitable for the cycle to repeat itself. And some females can lay more than one batch of eggs each time the rains come (if the water lasts long enough, of course). Not only can those eggs go dormant until the next rain comes, which is pretty cool in and of itself, but they can go dormant for almost 10 years, and some for up to a few decades! This allows for some of the eggs to hatch a month from now, and some to hatch a few years from now, ensuring that there are enough individuals to keep the species going.
I find these little guys to be just fascinating- they look to be fairly simple creatures anatomically speaking, and the fairy shrimp are even see-through, but they are so sensitive and complex that they will only come out of dormancy when just the right environmental conditions are present. To me, that is an impressive feat. And they’re pretty cute.
|Tadpole shrimp are all over the world, including our sister park Ikh Nart Nature Reserve in Mongolia! Photo by Steve Bier|
For now I’m anxiously waiting during our Flash Flood Warning, letting the clouds and humidity play their teasing game until either the humidity lets up or we get some rain. If we get some rain, you can be sure I’ll be marking my calendar to head out on an adventure to see some more of these fascinating desert creatures.
Want more from people that actually know more? Students from University of San Diego will present a poster on their research of ephemeral wetlands at the 2014 Colorado Desert Natural History Research Symposium - check it out on November 7! Student scholarships are available.