Description: This amphipod has a laterally compressed body that reaches up to 33 mm in length. The head has forward sloping lateral lobes, a small rostrum and large oval or kidney-shaped eyes. Antenna 1 some groups of setae, while antennae 2 has numerous groups. The back is smooth until the urosome which has conspicuous angular humps. Pereopod 7 has a few spines and setae. Rami (limb segments) in uropod 3 are almost equal in length and have numerous spines and setae.

Habitat: Found under stones and amongst algae from the midshore to the shallow sublittoral. Can be found in large numbers.

Distribution: Common all around Britain and Ireland.

Similar Species: Identification of gammarids can be extremely difficult as many diagnostic features are only apparent in adult males.

Key Identification Features:

• Small rostrum.
• Large kidney-shaped eyes.
• Smooth back until urosome, which is covered in conspicuous humps.
• Rami in uropod 3 almost equal in length.

Distribution Map from NBN: Gammarus locusta at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Gammarus locusta at iNaturalist World Species Observations database.

WoRMS: Gammarus locusta at World Register of Marine Species.