''Eulimnadia texana'', the Texas clam shrimp or desert shrimp, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

belonging to the

Limnadiidae Limnadiidae is a family of crustaceans in the order Spinicaudata that live in seasonal wetlands, inland saline pools and lakes. They are found on all the world's continents except Antarctica, and are distinguished from other families in the same ...

family. It is

endemic Endemism is the state of a species being found 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 found elsew ...

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. It is an arid land specialist, living for many years as a cyst and bursting into life at the arrival of rains, maturing rapidly in temporary pools and producing eggs that can remain dormant until the next rains occur, perhaps in many years time.

Description

Desert shrimps are

sexually dimorphic Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

. The males have their front two pairs of thoracic appendages modified into claws while the hermaphrodites have unmodified legs.

Distribution and habitat

Desert shrimps live in ditches, ponds, pools, and other ephemeral freshwater habitats in northern

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

and parts of the

southern Southern may refer to: Businesses * China Southern Airlines, airline based in Guangzhou, China * Southern Airways, defunct US airline * Southern Air, air cargo transportation company based in Norwalk, Connecticut, US * Southern Airways Express, M ...

and

southwestern United States The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural region of the United States that generally includes Arizona, New Mexico, and adjacent portions of California, Colorado, Ne ...

, west of the

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it f ...

Biology

Individual shrimps are either male or

hermaphrodite In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many Taxonomy (biology), taxonomic groups of animals (mostly invertebrate ...

. The hermaphrodites can fertilize their own eggs or can mate with males but are unable to mate with other hermaphrodites. This arrangement is called

androdioecy Androdioecy is a reproductive system characterized by the coexistence of males and hermaphrodites. Androdioecy is rare in comparison with the other major reproductive systems: dioecy, gynodioecy and hermaphroditism. In animals, androdioecy has bee ...

and is very rare among animals. The reproductive cycle varies between paired shrimps and isolated hermaphrodites and it is possible that using both strategies enhances the likelihood that fertile eggs will be available when the ephemeral water body in which they live dries up. Although to biologists, androdioecy seems a strategy unlikely to be successful, research using

biogeographical Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, i ...

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

and

paleontological Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (geology), epoch (roughly 11,700 years before present). It includes t ...

evidence has shown that the practice has persisted in the genus '' Eulimnadia'' for 24 to 180 million years. The shrimps are

omnivore An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutr ...

s and

filter feeder Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...

s, able to feed on the algae and microorganisms that also make use of the revived pool.

Life cycle

In the

Mojave Desert The Mojave Desert ( ; mov, Hayikwiir Mat'aar; es, Desierto de Mojave) is a desert in the rain shadow of the Sierra Nevada mountains in the Southwestern United States. It is named for the indigenous Mojave people. It is located primarily in ...

, standing water occurs for only a short time after it rains. Storms are a rare event, and when a downpour occurs in the summer (making the water warm enough),

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

of the desert shrimp spring into life. They have been lying in the dust and baked clay of a dried-up pool in a dormant state for years, looking like grains of sand. The nauplius larvae which hatch outgrow with great rapidity. They undergo

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...

and reach a reproductive size in four to seven days. Each hermaphrodite then produces clutches of up to 300 eggs once or twice a day. By the twelfth day of their lives, they may be long. During the course of their short lives, each may produce thousands of eggs. If time allows, several generations may occur. When the water evaporates and little remains of their pool, they dig a hole in the mud and bury their eggs as the water level falls. By the time the pool has dried, the shrimps are desiccated corpses. However, their eggs live on, waiting for the next rainstorm which may be decades away. During the intervening years, desert winds may carry away some of the eggs and a few may end up in locations where water accumulates after rain. This allows the shrimp to colonize new areas without traveling while active. Hermaphrodites live 25% to 50% longer than males in this species.

References

{{Taxonbar, from=Q4566841 Spinicaudata Freshwater crustaceans of North America Crustaceans described in 1871