I had read about them. I had seen pictures of them. I had heard mini-lecture/explanations about them. But I had never seen them with my own two eyes – alive and swimming in a vernal pool… until now! I think they might be one of the cutest things I’ve ever seen.
In this photo, the one on the bottom is definitely a female – the dark blob between her thorax and abdomen is a brood pouch containing eggs. I’m not sure about the other one. Fairy Shrimp have two sets of antennae. The second set on males should be extra long as it is used for grasping the female during mating… we can’t really see this indivdual’s other antennae. Maybe the other is also a female whose brood pouch has already been emptied? It sort of looks like there is an empty pouch there, doesn’t it?
Biologists say that Fairy Shrimp is an obligate species in vernal pools. In other words, Fairy Shrimp must breed in temporary, fishless pools that dry up in summer. Other obligate species are Wood Frogs and Mole Salamanders (Spotted, Marble, Jefferson, and Blue-spotted). If any of these species are found in a pool, it can be designated a true Vernal Pool. Vernal Pools have become a focus for many conservationists and there are many programs to locate and catalog them throughout the US. Click here to read about a Vermont Vernal Pool program, for example.
Fairy Shrimp are fresh water crustaceans that swim with 11 pairs of leaf-like legs. Here’s 8 seconds of video of the little critters swimming in a pan:
(The other dark wigglers in the pan are mosquito larvae.)
Fairy Shrimp have amazing adaptations for survival, including these noted in Scott Green’s article (link below):
Though the resting period usually varies between 6 to 10 months, eggs have been hatched in a laboratory after 15 years. Eggs have been subjected to temperatures as high as 99C and as low as -190 C and remained viable.
We visited several vernal pools last Friday and we saw one or two Fairy Shrimp in all. But one pool – the one that was shrinking most rapidly – that one was just teeming with them! It was amazing.