Photo by: Joanna Gilkeson/USFWS

San Diego Fairy Shrimp

Branchinecta sandiegonensis

  • Endangered

    (fws.gov)

  • U.S. Endangered Species Act

    (fws.gov)

  • Development, off-road vehicles, hybridization of species, competition, non-native plants, alteration of hydrology, and disease are all threats to this species (fws.gov).

  • They are found in Riverside, Orange, and San Diego counties of California and northwestern Baja California, Mexico (fws.gov).

  • They inhabit vernal pools and other shallow ephemeral waters that are non-vegetated. San Diego fairy shrimp hatch and mature in 1-2 weeks following rainfall that fills a vernal pool. Cysts are produced after reproduction and either remain in the female until she dies or are dropped to the bottom of the pool. Cysts can withstand various temperatures and can remain in a dried state until they hatch from rehydration in late winter or spring (fws.gov).

  • Further research on the negative effects of hybridization and plans to potentially focus on isolation techniques to replenish species.

  • San Diego fairy shrimp get confused with other fairy shrimp species. San Diego fairy shrimp males are distinguished from other species by the differences in the distal tip of the second antennae, which is located further from the attachment point. Female San Diego fairy shrimp are distinguished by the presence of paired dorsolateral spines on five of the abdominal segments, the length of the ovary, and the shape and length of the brood sac (fws.gov).

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Vernal Pool Fairy Shrimp

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Conservancy Fairy Shrimp