Tadpole-shrimp
Guides
Lepidurus
tadpole shrimp
Lepidurus is one of two extant genera of tadpole shrimp (order Notostraca), distinguished from Triops by morphological and ecological traits. Species inhabit temporary freshwater pools, vernal pools, and permanent lakes across diverse climates from Arctic tundra to desert regions. The genus exhibits notable life history flexibility, with resting eggs capable of surviving desiccation and freezing for decades. Some species are of conservation concern due to habitat specificity, while others serve as agricultural pests or bioindicators of environmental change.
Lepidurus packardi
Vernal Pool Tadpole Shrimp
Lepidurus packardi is a federally endangered, California endemic freshwater microcrustacean in the order Notostraca. It is an ephemeral wetland specialist restricted to vernal pools and other temporary water bodies. The species is a key food source for larval California Tiger Salamander and acts as an ecosystem engineer through bioturbation. It reaches approximately 5 cm in length with a shield-like carapace up to 3.5 cm long.
Pacifastacus leniusculus
Signal Crayfish
The signal crayfish is a large North American freshwater crayfish introduced to Europe in the 1960s to replace declining native fisheries. It has become one of the most ecologically impactful invasive decapods in Europe, outcompeting native crayfish and serving as a carrier of crayfish plague (Aphanomyces astaci). The species establishes self-sustaining populations rapidly, with six age cohorts documented within a few years of introduction. It shows sex- and size-specific coloration patterns, with males displaying more saturated and brighter ventral claw surfaces than females, suggesting a role in intraspecific communication.
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tadpole shrimp, shield shrimp
Triops is a genus of small branchiopod crustaceans in the order Notostraca, commonly known as tadpole shrimp or shield shrimp. The genus is distinguished by having only a pair of long, thin caudal extensions on the telson, unlike the related genus Lepidurus which bears an additional central platelike process. Some species are frequently sold as aquarium pets in dried egg kits, hatching upon contact with fresh water. In agricultural settings, particularly California rice cultivation, certain species function as early-season pests that damage germinating seedlings.
Triops longicaudatus
Longtail Tadpole Shrimp, American Tadpole Shrimp, Rice Tadpole Shrimp
Triops longicaudatus is a freshwater branchiopod crustacean commonly known as the longtail tadpole shrimp or rice tadpole shrimp. It inhabits ephemeral ponds and pools across western North America, South America, Japan, South Korea, and Pacific Islands. The species is notable for its ancient lineage—morphologically unchanged for over 170 million years—and its remarkable desiccation-resistant eggs that can survive decades in dry sediment before hatching upon rehydration. It displays multiple reproductive strategies including parthenogenesis, hermaphroditism, and sexual reproduction. In California agriculture, it is a significant early-season pest of rice, damaging germinating seeds in flooded fields.