THE XERCES SOCIETY FOR INVERTEBRATE CONSERVATION

Aquatic Invertebrates in Pacific Northwest Freshwater Wetlands
An Identification Guide and Educational Resource

Scuds in the genus Hyalella (family Hyalellidae) are fairly distinctive amphipods that are highly tolerant and can be found in a variety of habitats. There is disagreement as to whether there is a single species or multiple species in the Northwest.

The second antennae (lower) are similar in shape but longer than the first (upper), easily distinguishing Hyalella from any other amphipods. Corophium also has longer second antennae, but they are highly modified and leg-like.