Key to Aquatic Macroinvertebrates in Utah - 10+ Legs
Organisms with 10+ legs belong to the class Crustacea (with the exception of Podocopida which belongs to the class Ostracoda). There are 8 orders of Crustacea and 1 order of Ostracoda found in Utah.
Amphipoda (Scud or Side Swimmers)
Description: 5-25 mm in length. Amiphoda have laterally flattened bodies which forces them to swim on their side. They can be opaque, green, white, brown, or yellow in color.
Habitat: Can be found in all aquatic habitats. They are scavengers and detritivores of bottom sediments.
Anostraca (fairy shrimp, brine shrimp, or sea monkeys)
Description: 7-50 mm in length. Anastroca have cylindrical body with a distinct head and stalked eyes. They have 11 or 17 pairs of swimming legs. No carapace.
Habitat: Found in ephemeral ponds and pools in desert habitats and the Great Salt Lake.
Cladocera (water fleas)
Description: 0.2-3 mm in length. Cladocera have laterally flattened bodies with a carapace, with visible antennae, and 5-6 pairs of legs.
Habitat: Can be found in all aquatic environments.
Conchostraca (clam shrimp)
Description: 2-16 mm in length. Conchostraca are laterally flattened and covered with a clam shell-like carapace. They have 10-32 pairs of legs.
Habitat: Can be found in saline waters and temporary ponds near the bottom.
Description: 10-150 mm in length. Decapoda have a carapace, 5 pairs of legs with pinchers on the 2nd pair.
Habitat: Found in still and fast moving water.
Isopoda (Sow bug)
Description: 5-20 mm length. Isopoda have dorsoventrally flattened body and 7 pairs of legs. They are opaque to light brown in color. When disturbed they will roll up into a ball like pill bugs.
Habitat: Often found in cold springs and regulated rivers. Some species can be found in waters with organic waste.
Notostraca (Tadpole shrimp)
Description: 10-75 mm in length. Notostraca have a shield-like carapace and 35-71 pairs of legs on their abdomen & 2 well developed tails.
Habitat: Found in ponds & emphemeral habitats mostly in the desert and higher elevations.
Podocopida (Seed shrimp)
Description: Less than 1 mm in length. Ostracoda have been described as tiny bivalves with legs. Their body is encased within a single or bivalve carapace. They have a single antenna and may have a rostrum.
Habitat: Can be found in all aquatic habitats.