''Lepidurus packardi'', the vernal pool tadpole shrimp, is a small, rare species of tadpole shrimp (

Notostraca The order Notostraca, containing the single family Triopsidae, is a group of crustaceans known as tadpole shrimp or shield shrimp. The two genera, ''Triops'' and ''Lepidurus'', are considered living fossils, with similar forms having existed since ...

) found in temporary ponds of the western United States.ITIS Report: ''Lepidurus packardi'' (TSN 684669)
/ref>

Distribution

The

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

, where it lives in the endangered

vernal pool Vernal pools, also called vernal ponds or ephemeral pools, are seasonal pools of water that provide habitat for distinctive plants and animals. They are considered to be a distinctive type of wetland usually devoid of fish, and thus allow the saf ...

type of habitat, and other freshwater aquatic habitats including ponds, reservoirs, ditches, road ruts, and other natural and artificial temporary water bodies. The animal is found in several regions of California, including the Central Coast,

Sacramento Valley The Sacramento Valley is the area of the Central Valley of the U.S. state of California that lies north of the Sacramento–San Joaquin River Delta and is drained by the Sacramento River. It encompasses all or parts of ten Northern California ...

San Joaquin Valley The San Joaquin Valley ( ; Spanish language in California, Spanish: ''Valle de San Joaquín'') is the southern half of California's Central Valley (California), Central Valley. Famed as a major breadbasket, the San Joaquin Valley is an importa ...

, and southern

Sierra Nevada The Sierra Nevada ( ) is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primari ...

foothills. The southeastern Sacramento Valley contains about 15% of the remaining vernal pool

grassland A grassland is an area where the vegetation is dominance (ecology), dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes such as clover, and other Herbaceo ...

habitat in the state, and it has about 35% of the known occurrences of ''L. packardi''. 28% of all occurrences are in

Sacramento County, California Sacramento County () is a County (United States), county located in the U.S. state of California. As of the 2020 United States census, the population was 1,585,055. Its county seat is Sacramento, California, Sacramento, which has been the List ...

. Other areas with occurrences include the

Don Edwards San Francisco Bay National Wildlife Refuge Don Edwards San Francisco Bay National Wildlife Refuge (DESFBNWR) is a United States National Wildlife Refuge located in the southern part of San Francisco Bay, California. Its headquarters and visitor center are in the Baylands district of Fre ...

, several preserves in

Tehama County Tehama County ( ) is a county located in the northern part of the U.S. state of California. As of the 2020 census, the population was 65,829. The county seat and largest city is Red Bluff. Tehama County comprises the Red Bluff, California m ...

, and the vicinity of the cities of Chico, Redding, and Red Bluff. It has been noted at the Sacramento National Wildlife Refuge,

Travis Air Force Base Travis Air Force Base is a United States Air Force base under the operational control of Air Mobility Command (AMC), located three miles (5 Kilometre, km) east of the central business district of the city of Fairfield, California, Fairfield, i ...

, and the Jepson Prairie Preserve. In the San Joaquin Valley it has been noted at the

Merced Merced (; Spanish language, Spanish for "Mercy") is a city in, and the county seat of, Merced County, California, United States, in the San Joaquin Valley. As of the 2020 United States census, 2020 census, the city had a population of 86,333, up ...

and

San Luis National Wildlife Refuge The San Luis National Wildlife Refuge in the San Joaquin Valley of Central California is one of the great remnants of a historically bountiful wintering grounds for migratory waterfowl on the Pacific Flyway. Located in the Bear Creek, Salt Slough ...

s. There are occurrences in the Sierra foothills region in Tulare,

Fresno Fresno (; ) is a city in the San Joaquin Valley of California, United States. It is the county seat of Fresno County, California, Fresno County and the largest city in the greater Central Valley (California), Central Valley region. It covers a ...

, and Stanislaus Counties.USFWS
''Lepidurus packardi'' Five-year Review.
September 2007. It occurs outside California in the

Agate Desert The Agate Desert is a prairie located near White City, Oregon, of which is protected as the Agate Desert Preserve. The area is not in fact a desert as its name suggests; it is so named because of the abundance of agate, petrified wood, jasper, and ...

of Oregon.

Description

''Lepidurus packardi'' is about long. It has a shield-like

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

up to long. It has

compound eyes A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distin ...

, up to 48 pairs of phyllopods (swimming appendages), and two cercopods, pincer-like appendages at the end of its

telson The telson () is the hindmost division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment (biology), segment of the arthropod body, or an additional division that is not a true segm ...

, or tail segment. It is similar to,''Lepidurus packardi''.
The Nature Conservancy. but distinct from, the related species '' Lepidurus couesii''. The sexes can be distinguished by noting the egg sacs attached to the eleventh phyllopods of the female. The adult is

omnivorous An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize ...

, collecting food items with its phyllopods as it swims, climbs on vegetation, or digs in sediment. It is an

ecosystem engineer An ecosystem engineer is any species that creates, significantly modifies, maintains or destroys a habitat. These organisms can have a large impact on species richness and landscape-level heterogeneity of an area. As a result, ecosystem engine ...

in that it causes

bioturbation Bioturbation is defined as the reworking of soils and sediments by animals or plants. It includes burrowing, ingestion, and defecation of sediment grains. Bioturbating activities have a profound effect on the environment and are thought to be a ...

, producing so much

turbidity Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of both water clarity and wa ...

when it digs through the sediment that it may alter the

ecology Ecology () is the natural science of the relationships among living organisms and their Natural environment, environment. Ecology considers organisms at the individual, population, community (ecology), community, ecosystem, and biosphere lev ...

of its pool habitat by reducing plant cover. Reproduction occurs when temporary pools fill with water. Larger females have higher

fecundity Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population as opposed to a sole organism, while in population biology, it is considered similar to fertility, the capability to produc ...

, the clutch size ranging from eight to 61 eggs. The eggs can withstand a period of desiccation when the pool is dry; they will then hatch within three weeks of the pool refilling, often much more quickly. Desiccation is not required for hatching, however. The

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

hatches as a

metanauplius Metanauplius is an early larval stage of some crustaceans such as krill. It follows the nauplius stage. In sac-spawning krill, there is an intermediary phase called pseudometanauplius, a newly hatched form distinguished from older metanauplii by ...

. It undergoes

ecdysis Ecdysis is the moulting of the cuticle in many invertebrates of the clade Ecdysozoa. Since the cuticle of these animals typically forms a largely inelastic exoskeleton, it is shed during growth and a new, larger covering is formed. The remnant ...

, or molting, several times, growing more phyllopods each time. ''L. packardi'' takes about 38 days to mature, reproduces around its 54th day of life, and lives about 144 days. It is sexually mature when it is in carapace length. Fecundity is much reduced in individuals which are infested with a

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

echinostome fluke.

Conservation

''Lepidurus packardi'' is a listed federally as an

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...

and by the

IUCN RedList The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological spe ...

. Threats to ''L. packardi'' include anything that destroys, degrades, or fragments its ephemeral pool habitat. Nine percent of historical vernal pool habitat remains today, and it is fragmented and isolated. Expanding urban development is the cause of

habitat destruction Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

in many areas. Agricultural development is another cause. The construction of the

University of California, Merced The University of California, Merced (UC Merced or colloquially, UCM) is a Public university, public Land-grant university, land-grant research university in Merced, California, United States. It is one of the ten campuses in the University of ...

, campus was scheduled to alter the habitat in the area, but it also included plans for protection of over . Habitat can also be degraded when the local

hydrology Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and drainage basin sustainability. A practitioner of hydrology is called a hydro ...

is altered, making the land too dry or permanently wet. There are many local conservation projects tailored to the needs of each region.

References

External links

UC CalPhotos gallery of ''Lepidurus packardi'' (vernal pool tadpole shrimp) images
{{Taxonbar, from=Q1089329 Notostraca Endemic crustaceans of the United States Freshwater crustaceans of North America Endemic fauna of California Fauna of the California chaparral and woodlands Natural history of the California Coast Ranges Natural history of the Central Valley (California) Natural history of the Transverse Ranges Endangered fauna of California Endangered fauna of the United States Crustaceans described in 1886 Taxonomy articles created by Polbot