Thursday, March 17, 2011
A tiny fairy shrimp, genus Eubranchipus, drifts in the water column. This is an amazing shot of one of our strangest creatures, and I thank Gary Meszaros for sending it along. It takes specials skills and equipment to make photographs such as this one.
Fairy shrimp are fairly common in our vernal pools, but it's easy to miss them. An adult might tape out at one-half inch in length or so, and they're nearly translucent. They are indeed distant relatives of the shrimp that grace your dinner plate; both are in the Class Crustacea.
Now is the time to look for these tiny swimmers. When vernal pools are in their flooded springtime glory, the fairy shrimp almost magically come to life and occasionally good numbers of them can be observed wafting through the water. They definitely prefer cool water. Once the vernal pool warms to 60 degrees or so they begin to vanish. There are apparently a few different species in Ohio; I'm not sure which one this is.
Oh, what beautiful stalked eyes you have! Photoreceptors in those eyes tend to draw the animal in the direction of light, so shining a flashlight into the water at night sometimes lures the shrimp. Fairy shrimp are predators, feeding upon tiny invertebrate animal life and sometimes algae and decaying plant material. In turn, the shrimp stoke the discerning palates of Wood Ducks, other birds, and larger insects such as predacious diving beetles.
This shrimp is a female, as evidenced by this brood pouch filled with cysts. The cysts are embryonic shrimp that are encased in a hard shell. These tiny shrimp-to-be are rather indestructable and can survive passage through a duck's digestive system, dessication, and extremes of heat or cold. The cysts of related species have been found buried in soil, and estimated at 10,000 years of age. Some of these ancient fairy shrimp cysts have proven to be viable!
Vernal pools, ephemeral as they usually are, are amazing habitats tht burst with all manner of life during their brief glory. This incredible fairy shrimp photo is from the brand new book Animals of Ohio's Ponds and Vernal Pools, by David Fitzsimmons and Gary Meszaros. It'll soon be available, and if you have an interest in natural history, you'll do well to get a copy. Ordering information HERE.