''Jassa marmorata'' is a species of tube-building

amphipod Amphipoda () is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods () range in size from and are mostly detritivores or scavengers. There are more than 10,700 amphipod species cur ...

. It is native to the northeast

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

but has been introduced into northeast

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

. ''J. marmorata'' are greyish in colour with reddish brown markings. The can grow to a length of up to . They are generally found in fouling communities and intertidal areas where they build tubes of

detritus In biology, detritus ( or ) is organic matter made up of the decomposition, decomposing remains of organisms and plants, and also of feces. Detritus usually hosts communities of microorganisms that colonize and decomposition, decompose (Reminera ...

and

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

fragments using silky mucus secretions. They are remarkable for having two distinct morphs of males with two different mating strategies. The 'major' morphs are fighter males, while the 'minor' morphs are sneaker males. ''J. marmorata'' is classified under the genus '' Jassa'' of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Ischyroceridae. They are commonly confused with the closely related scud ('' Jassa falcata'').

References

Corophiida Amphipods of the Atlantic Ocean Crustaceans described in 1905 {{Amphipod-stub