Lepidurus packardi is a rare species of tadpole shrimp

Notostraca

The order Notostraca comprises the single family Triopsidae, containing the tadpole shrimp or shield shrimp. The two genera, Triops and Lepidurus, are considered living fossils, having not changed significantly in outward form since the Triassic. They have a broad, flat carapace, which conceals the...

 known by the common name vernal pool tadpole shrimp. It is native to California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 and southern Oregon

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

, where it lives in an endangered type of habitat, the vernal pool

Vernal pool

Vernal pools, also called vernal ponds or ephemeral pools, are temporary pools of water. They are usually devoid of fish, and thus allow the safe development of natal amphibian and insect species...

, and other freshwater aquatic habitats. It is a federally listed endangered species

Endangered species

An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

 of the United States.

This crustacean

Crustacean

Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

 is about 5 centimetres (2 in) long. It has a shield-like carapace

Carapace

A carapace is a dorsal 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 underside is called the plastron.-Crustaceans:In crustaceans, the...

 up to 3.5 cm (1.4 in) long. It has compound eyes, up to 48 pairs of phyllopods (swimming appendages), and two cercopods, pincer-like appendages at the end of its telson

Telson

The telson is the last division of the body of a crustacean. It is not considered a true segment because it does not arise in the embryo from teloblast areas as do real segments. It never carries any appendages, but a forked "tail" called the caudal furca is often present. Together with the...

, or tail segment. It is similar to, 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.

L. packardi lives in vernal pools, ponds, reservoirs, ditches, road ruts, and other natural and artificial temporary water bodies. The adult is omnivorous

Omnivore

Omnivores are species that eat both plants and animals as their primary food source...

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

Ecosystem engineer

An ecosystem engineer is any organism that creates or modifies habitats. Jones et al. identified two different types of ecosystem engineers:...

 in that it causes bioturbation

Bioturbation

In oceanography, limnology, pedology, geology , and archaeology, bioturbation is the displacement and mixing of sediment particles and solutes by fauna or flora . The mediators of bioturbation are typically annelid worms , bivalves In oceanography, limnology, pedology, geology (especially...

, producing so much turbidity

Turbidity

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

 when it digs through the sediment that it may alter the ecology

Ecology

Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...

 of its pool habitat by reducing plant cover.

Reproduction occurs when temporary pools fill with water. Larger females have higher fecundity

Fecundity

Fecundity, derived from the word fecund, generally refers to the ability to reproduce. In demography, fecundity is the potential reproductive capacity of an individual or population. In biology, the definition is more equivalent to fertility, or the actual reproductive rate of an organism or...

, 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

Crustacean larvae

Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow...

 hatches as a metanauplius

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 its extremely short abdomen...

. It undergoes ecdysis

Ecdysis

Ecdysis is the moulting of the cuticula in many invertebrates. This process of moulting is the defining feature of the clade Ecdysozoa, comprising the arthropods, nematodes, velvet worms, horsehair worms, rotifers, tardigrades and Cephalorhyncha...

, 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 10–12 mm (0.393700787401575–0.47244094488189 ) in carapace length. Fecundity is much reduced in individuals which are infested with a parasitic echinostome

Echinostoma

Echinostoma is an important genus that includes many parasites.Human echinostomiasis is an intestinal parasitic disease caused by one of at least sixteen trematode flukes from the genus Echinostoma. Found largely in southeast Asia and the Far East, mainly in cosmopolitan areas. It has extensive...

 fluke

Trematoda

Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as "flukes".-Taxonomy and biodiversity:...

.

L. packardi is found in several regions of California, including the Central Coast, Sacramento Valley

Sacramento Valley

The Sacramento Valley is the portion of the California Central Valley that lies to the north of the San Joaquin-Sacramento Delta in the U.S. state of California. It encompasses all or parts of ten counties.-Geography:...

, San Joaquin Valley

San Joaquin Valley

The San Joaquin Valley is the area of the Central Valley of California that lies south of the Sacramento – San Joaquin River Delta in Stockton...

, and southern Sierra Nevada foothills. The southeastern Sacramento Valley contains about 15% of the remaining vernal pool grassland

Grassland

Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...

 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, California

Sacramento County is a county in the U.S. state of California. Its county seat is Sacramento, which is also the state capital. As of 2010 the county had a population of 1,418,788....

. Other areas with occurrences include the Don Edwards San Francisco Bay National Wildlife Refuge

Don Edwards San Francisco Bay National Wildlife Refuge

Don Edwards San Francisco Bay National Wildlife Refuge is a US National Wildlife Refuge located in the southern part of San Francisco Bay, California. The Refuge headquarters and visitor center is located in the Baylands district of Fremont, next to Coyote Hills Regional Park, in Alameda County. ...

, several preserves in Tehama County

Tehama County, California

Tehama County is a county located in the northern part of the U.S. state of California. It is bisected by the Sacramento River. As of 2010 its population was 63,463, up from 56,039 as of 2000. The county seat is Red Bluff.-History:...

, and the vicinity of the cities of Chico

Chico, California

Chico is the most populous city in Butte County, California, United States. The population was 86,187 at the 2010 census, up from 59,954 at the time of the 2000 census...

, Redding

Redding, California

Redding is a city in far-Northern California. It is the county seat of Shasta County, California, USA. With a population of 89,861, according to the 2010 Census...

, and Red Bluff

Red Bluff, California

Red Bluff is a city in and the county seat of Tehama County, California, United States. The population was 14,076 at the 2010 census, up from 13,147 at the 2000 census....

. It has been noted at the Sacramento National Wildlife Refuge, Travis Air Force Base

Travis Air Force Base

Travis Air Force Base is a United States Air Force air base under the operational control of the Air Mobility Command , located three miles east of the central business district of Fairfield, in Solano County, California, United States. The base is named for Brigadier General Robert F...

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

Merced National Wildlife Refuge

The Merced National Wildlife Refuge encompasses of wetlands, native grasslands, vernal pools, and riparian areas. It was established in 1951 under the Lea Act to attract wintering waterfowl from adjacent farmland where their foraging was causing crop damage...

 and San Luis National Wildlife Refuge

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...

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

Tulare County, California

Tulare County is a county located in the Central Valley of the U.S. state of California, south of Fresno. Sequoia National Park is located in the county, as are part of Kings Canyon National Park, in its northeast corner , and part of Mount Whitney, on its eastern border...

, Fresno

Fresno County, California

Fresno County is a county located in the Central Valley of the U.S. state of California, south of Stockton and north of Bakersfield. As of the 2010 census, it is the tenth most populous county in California with a population of 930,450, and the sixth largest in size with an area of . The county...

, Merced

Merced County, California

Merced County , is a county located in the Central Valley of the U.S. state of California, north of Fresno and southeast of San Jose. As of the 2010 census, the population was 255,793, up from 210,554 at the 2000 census. The county seat is Merced...

, and Stanislaus Counties

Stanislaus County, California

Stanislaus County is a county located in the Central Valley of the U.S. state of California. As the price of housing has increased in the San Francisco Bay Area, many people who work in the southern reaches of the Bay Area have opted for the longer commute and moved to Stanislaus County for the...

. It occurs outside California in the Agate Desert

Agate Desert

The Agate Desert is a prairie located Jackson County, Oregon, United States, in the area of White City. Much of the World War II army training base Camp White was built in the Agate Desert...

 of Oregon.

Threats to L. packardi include anything that destroys, degrades, or fragments

Habitat fragmentation

Habitat fragmentation as the name implies, describes the emergence of discontinuities in an organism's preferred environment , causing population fragmentation...

 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 in many areas. Agricultural development is another cause. The construction of the University of California, Merced

University of California, Merced

The University of California, Merced, commonly referred to as UC Merced or UCM, is the tenth and newest of the University of California campuses. Located in the San Joaquin Valley in unincorporated Merced County, California, near Merced, UC Merced was the first American research university to...

, campus was scheduled to alter the habitat in the area, but it also included plans for protection of over 20000 acres (8,093.7 ha). Habitat can also be degraded when the local hydrology

Hydrology

Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability...

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

External links

• Lepidurus packardi. CalPhotos Photo Gallery.