10+ Legs


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    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)

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    Description5-25 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.

    HabitatCan be found in all aquatic habitats. They are scavengers and detritivores of bottom sediments.

    Anostraca (fairy shrimp, brine shrimp, or sea monkeys)

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    Description7-50 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.

    HabitatFound in ephemeral ponds and pools in desert habitats and the Great Salt Lake.

    Cladocera (water fleas)

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    Description0.2-3 mm in length. Cladocera have laterally flattened bodies with a carapace, with visible antennae, and 5-6 pairs of legs.

    HabitatCan be found in all aquatic environments. 

    Conchostraca (clam shrimp)

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    Description2-16 mm in length. Conchostraca are laterally flattened and covered with a clam shell-like carapace. They have 10-32 pairs of legs.

    HabitatCan be found in saline waters and temporary ponds near the bottom.


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    Description1-2 mm in length. Copepods have cylindrical, segmented bodies with appendages on the head and thorax. They have 6 pairs of legs and 2 tail like structures on the posterior end of the abdomen.

    HabitatIn still and rapid moving fresh water.

    Other Imagescepepoda

    Decapoda (Crayfish)

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    Description10-150 mm in length. Decapoda have a carapace, 5 pairs of legs with pinchers on the 2nd pair.

    HabitatFound in still and fast moving water. 

    Isopoda (Sow bug)

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    Description5-20 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.

    HabitatOften found in cold springs and regulated rivers. Some species can be found in waters with organic waste.

    Notostraca (Tadpole shrimp)

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    Description10-75 mm in length. Notostraca have a shield-like carapace and 35-71 pairs of legs on their abdomen & 2 well developed tails.

    HabitatFound in ponds & emphemeral habitats mostly in the desert and higher elevations. 

    Podocopida (Seed shrimp)

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    DescriptionLess 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.

    HabitatCan be found in all aquatic habitats.

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