Tadpole Shrimps Fairy Shrimps and Clam Shrimps and Water Fleas: Branchiopoda

Physical characteristics: The longtail tadpole shrimp is a large species that reaches up to 1.5 inches (40 millimeters) in length. The second maxilla is absent.

Geographic range: The species is found in North America (including Hawaii but not Alaska), Central America, South America, Japan, the West Indies, the Galápagos Islands, and New Caledonia.

Habitat: The longtail is the most widely distributed of all tadpole shrimps. It is found in a wide variety of temporary waters, including rice fields.

Diet: Longtail tadpole shrimps scavenge both living and dead plant and animal materials. They also prey on microscopic animals, insect larvae, other small crustaceans, and even each other.

Longtail tadpole shrimps scavenge both living and dead plant and animal materials. They also prey on microscopic animals, insect larvae, other small crustaceans, and even each other. (Illustration by Bruce Worden. Reproduced by permission.)

Behavior and reproduction: They root about on the bottom of temporary pools in search of food. When oxygen levels are low, they swim upside down near the water surface.

They reproduce by mating or parthenogenesis.

Longtail tadpole shrimps and people: The longtail tadpole shrimp is sometimes considered a pest in rice fields mainly in the United States and Spain, where it damages the roots and leaves of rice plant seedlings. In large numbers this species stirs up the muddy bottom, blocking out sunlight needed by developing plants. In Japan, rice plants are too big to be eaten. Instead, the tadpole shrimps attack unwanted weeds. As a result, they are considered to be beneficial. Their dried eggs are sold in breeding kits to schools and to people interested in raising unusual pets.

Conservation status: This species is not considered endangered or threatened. ∎