Eye muscle nerves nuclear size in a breed of domestic rabbits with floppy ears

In many wild species there is a correlation between the capacity for directional hearing and directional seeing, which is associated with the mobility of the eye balls. Among the breeds of domestic rabbits, there are some with pendulous, floppy external ears (e.g., Englische Widder, EW) that might limit directional hearing. The size of the brain stem nuclei in EWs has been determined and compared to rabbits with upright ears. In EW, the oculomotor nuclei are relatively larger than in the other breeds. Possibly, this indicates a compensation of a loss in directional hearing ability achieved through greater mobility of the eyes. At the same time, a variability of brain composition between the breeds, which is an intraspecific variability, is obvious.