Vernal Pool Tadpole Shrimp, Lepidurus packardi

The vernal pool tadpole shrimp (Lepidurus packardi) is a species of shrimp that can be found in California and southern areas of Oregon. Its range includes the Agate Desert in Oregon and many areas in California including the Central Coast, the San Joaquin and Sacramento Valleys, and the southern foothills of the Sierra Nevada. This species prefers to reside in vernal pools, which are now rare, but it can be found in other freshwater habitats including ditches, reservoirs, and ponds.

The vernal pool tadpole reaches an average body length of two inches, while its carapace only reaches 1.4 inches. This species has two pincer-like appendages on its tail end and swims using forty-eight phyllopods. The eleventh phyllopods on females hold egg sacs, which distinguish them from males. Adult members of this species consume a number of food types, gathering them with their phyllopods as they move across sediment, vegetation, or as they swim through the water. It is thought to cause bioturbation when it digs through the sediment, even removing plants from certain areas.

The vernal pool tadpole shrimp breeds when temporary pools fill with water, where females will lay egg sacs containing eight to sixty-one eggs, depending upon the size of the female. If the pool dries out, eggs can last for up to three weeks until the pool fills again, but this desiccation is not needed for the eggs to hatch. After hatching, the larvae will molt many times throughout a thirty-eight day period until they are full-grown adults. This species can reproduce when it reaches between 0.4 and 0.5 inches and for 144 days.

The main threats to the vernal pool tadpole shrimp include habitat loss caused by fragmentation and destruction and only nine percent of its original habitat remains today. It has lost much of its habitat due to human encroachment and agricultural developments. Many conservation efforts have been enacted for this species, varying in different areas of its range. The vernal pool tadpole shrimp appears on the IUCN Red List with a conservation status of “Endangered.”

Image Caption: Lepidurus packardi. Credit: Bill Stagnaro/Wikipedia (CC BY-SA 3.0)