FAMILY: Crangonyctidae

DESCRIPTION: The Hay's spring amphipod is a small, aquatic crustacean that resembles a very tiny shrimp — 5-10 millimeters in length, colorless and blind. It possesses small hairs on its body that sense water currents and help it search for food, mostly small pieces of leaf litter and dead insects.

HABITAT: In general amphipods in the genus Stygobromus tend to live in caves or other underground areas where there are permanent groundwater habitats that contain low levels of organic matter such as decomposing leaf litter and dead insects, on which they feed. In Rock Creek Park, thick layers of clay lie beneath freshwater seeps, stopping the water and creating perched pockets of subterranean habitat. Some research suggests that the Hay's Spring amphipod may also be able to live in a few other valley floor habitats within Rock Creek Park that have shallow subsurface groundwater that are high in organic matter and may even be seasonally dry. These habitats occur when groundwater seeps to the surface from underlying bedrock to flow up through sediments and vegetative litter.

RANGE: Five to eight springs in Rock Creek Park. Total occupied area likely less than 120 square meters.

MIGRATION: The species is not known to migrate.



FEEDING: Small fragments of dead leaves and insects

THREATS: The greatest threats facing Hay's spring amphipod are habitat destruction and water pollution.

POPULATION TREND: The population is likely stable, but critically imperiled.

Photo of habitat for Hay's' spring amphipod by Brett Hartl