Can you recognise this larva? It moved in a dramatic rocking / squirming motion.
It was in the River Chess, a chalk stream.
No interactions present.
Then again, it could be a stonefly. I'll wait for the voting.
Very distinctive Hydropsychid shape and colour - hard plates on the thorax and can just make out the gills poking out from the underside. But can't tell species from the picture - most species have pale markings on the head.
The notes about the rocking motion is characteristic for this family. It is a way of getting themselves off the bottom so that the current will carry them away to hopefully better conditions.
Ian Wallace, UK Trichoptera Recording Scheme
Lat/Lng: 51.6908549, -0.5881955
OS grid ref: SP976000
In the River Chess, a chalk stream.