Eurydice are small, fast-swimming predators and scavengers with oval bodies and elongated pleotelsons. The peduncle of the antenna has four segments, whilst the second segment of the antennule is at a right angle to the first. The body is off-white with various darker markings, and the eyes are prominent.
E. spinigera is distinguishable from E. pulchra and E. affinis in having a concave hind margin on the pleotelson with two prominent spines at each corner, the space between filled with plumose setae. The shape of the coxal plates in this species is particularly distinctive, with their posterior corners (especially those of pleon somite 6) having long points.
In addition to the two other Eurydice species that are encountered intertidally, fieldworkers should be aware of the three other species that occur in (offshore) British waters, E. inermis, E. truncata and E. grimaldii (see Hansen 1905 and Jones & Naylor 1967 for details), the first two of which can come close to the shore at high tide.
Distribution and Habitat
E. spinigera is essentially an off-shore species, though it may turn up intertidally over sand on southern and western shores.
Hansen, H. J. 1905. Revision of the European marine forms of Cirolaninae, a subfamily of Crustacea Isopoda. Journal of the Linnean Society, Zoology 29: 337-373.
Jones, D. A. & E. Naylor. 1967. The distribution of Eurydice [Crustacea: Isopoda] in British Waters, including E. affinis new to Britain. Journal of The Marine Biological Association of the United Kingdom 47, 372-82.
Naylor, E. & A. Brandt. 2015. Intertidal Marine Isopods. Synopses of the British Fauna (New Series), No. 3. Field Studies Council, for The Linnean Society of London.