Streptoneuria

Streptoneuria

Streptoneuria is a crossover of main nerve cords caused by ontogenetic torsion (rotation) of the body. They can be found, for example, in front gills (Prosobranchia). Here, the torsion of the viscera leads, among other things, to the displacement of the gills forwards over the head, which favors the oxygen supply due to the orientation of the flow opposite.

With hind gills (Opisthobranchiata) there is usually a reverse rotation.