fairy shrimp

san diego fairy shrimp

To view the photo above, you will need Macromedia Flash Player
photo copyrighted, do not reproduce
photo by Anthony Mercieca©

(Branchinecta sandiegonensis)

The San Diego fairy shrimp breeds in vernal pools. It takes only two weeks to go from egg to reproductive adult. They are among the most characteristic of the vernal pool invertebrates. The young shrimp swim upside down in the pools, filter feeding on algae and zooplankton, using their many legs. As they reach maturity, the female develops prominent ovisacs while the males' second antennae become modified for clasping the female during mating. Females lay 100-300 eggs or more. When laid, the eggs fall to the soil surface where they develop to the gastrula (early embryo) stage, then become dormant until the next wet season.

Fairy shrimp occur in vernal pools on the Sweetwater Reservoir site. Population declines were due primarily to habitat loss from agricultural and urban development, alteration of wetland hydrology by draining, off-road vehicle activity, cattle grazing, and replacement by other fairy shrimp species that are habitat generalists. Listed as Federally endangered in 1997. A Recovery Plan was finalized 1998 that emphasizes that vernal pools are not independent of one another but rather a part of a vernal pool complex and that individual pools should be treated as subpopulations. Furthermore, the primary goal in the recovery of the fairy shrimp is to secure existing vernal pools and their watersheds from further loss and degradation in a configuration that maintains habitat function and species viability.