Description: This amphipod is reddish brown with patches of white marbling on the body, antennae and gnathopods It reaches up to 10 mm in size and lives in self-constructed tubes. Eyes are small, round and dark in colour. They have two robust pairs of antennae.

Habitat: Lives in tubes built from debris, either on solid structures (e.g. pilings, hulls of ships, buoys) or amongst algae and hydroids. Can be very common on ships and in harbours/marinas. Found both intertidally and sublittorally.

Distribution: True distribution uncertain as there has been some confusion over identification of Jassa species, especially distinguishing between J. falcata, J. herdmani and J. marmorata.

Similar Species: Jassa species may be easily confused, and there are a number of superficially similar looking amphipods found in Britain and Ireland so careful inspection, using a microscope, and use of specialist identification guides may be required.

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

iNaturalist: Jassa marmorata at iNaturalist World Species Observations database.

WoRMS: Jassa marmorata at World Register of Marine Species.