Some Morphological, Physiological and Behavioral Specializations in North American Beavers (Castor canadensis)

Abstract

To gain insight into the functional properties of the tail in North American beavers (C. canadensis) morphological features of skeletal, muscular, vascular, cutaneous and neural structures were performed; the segmental organization of spinal roots and certain stimulus-response features of receptive fields of single dorsal root fibers were studied; the main somatic sensory area (SI) of the cerebral neocortex was mapped, and these findings were related to observations of tail behavior in living beavers. The behavioral observations revealed the beaver capable of forceful yet discrete movements of the tail in water. A morphological correlate of these motor skills was the distinct segmentally organized pattern of serial muscle tendon arrangements and spinal sensory and motor innervation. Neither the receptors innervating the scales or hairs of the tail, the stimulus-response properties of single dorsal root afferents nor the representation of the tail in SI suggested unusual cutaneous sensory capabilities associated with the morphological and behavioral specializations exhibited by the beaver''s tail.