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In California, most anostracan crustaceans inhabit ephemeral wetlands, such as vernal peels, mountain meadows, and desert playas with biphasic wet/dry cycles. The shrimps hatch and mature during the aquatic phase and deposit dormant cysts which remain in the soil through the dry phase. In some habitats, due to the variable nature of local rainfall patterns, pools at times fill only partially and dry quickly before the shrimp are able to mature and reproduce. Species in such unpredictable environments produce cysts that do not all hatch when first hydrated. A portion remain dormant and hatch in later pool fillings. We investigated the hatching pattern of two newly described species of anostracans found in unpredictable vernal pools in southern California, U.S.A., Branchinecta sandiegonensis Fugate and Streptocephalus woottoni Eng et al. Hatching rates for these species were among the lowest yet reported for anostracans. Initial hatch from the soil cyst bank was 6% for B. sandiegonensis and 0.18% for S. woottani and cumulative totals were 28% and 2.8%, respectively, over 3 hydrations. Furthermore, hatching variability was demonstrated for the cysts of single pairs. This life-history pattern conforms to the 3 major predictions of models of diversified risk-spreading or bet-hedging strategies as developed for annual plants.