Clam-shrimp
Guides
Eulimnadia
clam shrimp
Eulimnadia is a genus of small freshwater branchiopods commonly known as clam shrimp. The genus is notable for its rare androdioecious mating system, where populations consist of males and hermaphrodites but lack pure females. This reproductive strategy has persisted for an estimated 24–180 million years across multiple speciation events, making it one of the most stable examples of androdioecy known in animals. Species are distinguished primarily by the morphology of their resting eggs (cysts), which show distinctive sculpturing patterns. The genus contains approximately 13–25 described species with a cosmopolitan distribution across every continent except Antarctica.
Eulimnadia geayi
Eulimnadia geayi is a small freshwater crustacean in the family Limnadiidae, commonly known as clam shrimp. First described by Eugen von Daday in 1913, this species inhabits temporary aquatic habitats across Central and South America. Like other members of its genus, it produces drought-resistant eggs that survive in dry sediment until rainfall triggers hatching. The species plays a role in ephemeral pool food webs as both a detritivore and prey item.
Laevicaudata
clam shrimp
Laevicaudata is a suborder of small branchiopod crustaceans commonly known as clam shrimp, characterized by a laterally compressed bivalved carapace that encloses the entire body. The group contains approximately 36 described species in the single family Lynceidae, with the genus Lynceus as the primary representative. Laevicaudatans inhabit temporary freshwater habitats worldwide, with documented occurrences across six continents including remote insular locations. The group has been historically understudied compared to other large branchiopods, though recent taxonomic revisions have clarified species boundaries, particularly in Australia where six species are now recognized.
Lynceidae
clam shrimp
Lynceidae is a family of small, bivalved crustaceans commonly known as clam shrimp, classified in the order Laevicaudata. The family contains approximately 5 genera and more than 20 described species, with the genus Lynceus being the most species-rich and well-studied. Members are distinguished from other clam shrimp families by specific morphological features of the carapace, head, and male clasping appendages. Lynceidae species inhabit temporary aquatic habitats across multiple continents, though many species have restricted distributions due to habitat destruction.
Lynceus
clam shrimp
Lynceus is a genus of clam shrimp in the family Lynceidae, comprising approximately 13 described species. These small branchiopod crustaceans inhabit temporary aquatic habitats, including desert rockholes, gnammas, and dolines. The genus has been subject to recent taxonomic revision, particularly in Australia where six species are now recognized. Species identification relies on morphological characters including male first thoracopod structure, head and rostrum form, antenna 2 spinal patterns, carapace shape, and the female lamina abdominalis.
Spinicaudata
clam shrimp
Spinicaudata is an infraorder of small, bivalved branchiopod crustaceans commonly known as clam shrimp. They inhabit temporary freshwater pools, saline lakes, and rock holes (gnammas) across arid and semi-arid regions worldwide. The group is characterized by a laterally compressed body enclosed within a hinged, clam-like carapace. Many species produce drought-resistant resting eggs that persist in dry sediments until favorable conditions return. Reproductive modes vary, with some lineages exhibiting androdioecy (hermaphrodites with occasional males) and others gonochorism (separate sexes with ~1:1 ratios).