Identifié en laboratoire
Larger one was actively carrying the smaller underneath it.
The detached leg is pereopod 7. Keys to J. forsmani but Naylor & Brandt book says this species is not in low salinity. Conductivity here was 15700 microS/cm @ 25C, about 23% seawater. The habitat is odd - an intermittent saline stream. I suspect it is pumped out of a sump under the A55 road tunnel. It flows for a few minutes then stops.
Maybe genus Jaera, but I'm not sure. Found several of these (some of which were even smaller than this one) in amongst some slightly wet seaweed. I put it back on some seaweed after photographing it.
The detached leg is pereopod 7. Keys to J. forsmani but Naylor & Brandt book says this species is not in low salinity. Conductivity here was 15700 microS/cm @ 25C, about 23% seawater. The habitat is odd - an intermittent saline stream. I suspect it is pumped out of a sump under the A55 road tunnel. It flows for a few minutes then stops.