Ephemeral species are plants and animals whose lifespan lasts only a few weeks or months. The most common types of ephemeral species are desert annuals, plants whose seeds remain dormant for months or years but which quickly germinate, grow, and flower when rain does fall. In such cases the amount and frequency of rainfall determine entirely how frequently ephemerals appear and how long they last. Tiny, usually microscopic, insects and other invertebrate animals often appear with these desert annals, feeding on briefly available plants, quickly reproducing, and dying in a few weeks or less. Ephemeral ponds, short-duration desert rain pools, are especially noted for supporting ephemeral species. Here small insects and even amphibians have ephemeral lives. The spadefoot toad (Scaphiopus multiplicatus), for example, matures and breeds in as little as eight days after a rain, feeding on short-lived brine shrimp, which in turn consume algae and...