by Emma Kull, MNA Communications Intern
A vernal pool fills with water around the springtime, bringing new life. Here, a small crustacean hatches; a lesser known relative of the lobster.
This crustacean’s common name, fairy shrimp, is the perfect nod to its graceful demeanor in the water and its small, delicate body. These aquatic dancers glide through the water on their backs by slowly rippling their eleven pairs of legs to create propulsion. They vary in size but are typically around three quarters of an inch long.
The fairy shrimp would not be able to survive without the protective habitat created by the emergence of vernal pools each year. Though the ephemeral nature of vernal pools makes them a safe place for fairy shrimp to live without fish predators, surviving in such impermanent conditions is no small task. Fortunately, fairy shrimp are well adapted to do just that.
Once their eggs hatch, fairy shrimp have relatively short life cycles, only about a few weeks, allowing them to age and usually reproduce within the short window provided by the pool. In the case that the vernal pool dries up too quickly for the fairy shrimp to reproduce, these clever crustaceans have a backup strategy. Each spring, only a segment of the fairy shrimp eggs that had been laid the previous year will hatch, leaving the rest to remain dormant for potentially several years. That means that the fairy shrimp population can continue to survive, even if the pool doesn’t fill with water one year.
The presence of fairy shrimp is a sign of a healthy ecosystem, as it is considered an indicator species to confirm the presence of a vernal pool; and is exciting to behold if you are lucky enough to witness it.
As a lead partner of the Michigan Vernal Pools Partnership, the Michigan Nature Association is committed to protecting vernal pools for all of the species that use them at a number of our more than 180 Nature Sanctuaries throughout Michigan.