Vernal pool fairy shrimp, Branchinecta lynchi

About this species

Federal: Threatened

(=) Stable



Southern Oregon to northern Baja California


The vernal pool fairy shrimp is a small (1 to 2.5 cm) freshwater crustacean that resembles a translucent shrimp. It has a brief lifespan of two months when vernal pools fill with water.

Habitat & Behavior

As their name suggests, vernal pool fairy shrimp only live in seasonal vernal pools. Vernal pools have an impervious substrate that fills with water during winter rains and slowly dries up from spring to summer.


Almost all vernal pool habitats in the Los Angeles basin have been developed because they occur on flat, easy-to-develop slopes. Many have been replaced or degraded by urban and agricultural development, pasture, altered hydrology, off-road vehicle use, trampling, and non-native plants. Cruzan Mesa contains the only remaining vernal pool habitat in Los Angeles County.


In Los Angeles, the vernal pool fairy shrimp occurs in several pools at Cruzan Mesa. This protected area has been fenced and is only accessible to state and federal nature resource managers.

Where can you spot it?

Vernal pool fairy shrimp habitat is protected and access is limited. However, other Southern California vernal pools can be visited at the Santa Rosa Plateau Ecological Reserve near Murrieta.

What is critical habitat?

Critical habitat refers to an area that is believed to be essential to the conservation of a federally endangered or threatened species. The designated area does not necessarily include the species entire range.

Learn more

Data source: Critical habitat from US Fish and Wildlife Service, accessed via ECOS (Environmental Conservation Online System)


  • U.S. Fish & Wildlife Service. “Recovery Plan for Vernal Pool Ecosystems of California and Southern Oregon.” [link]