PREHENSILE USE OF PERIORAL BRISTLES DURING FEEDING AND ASSOCIATED BEHAVIORS OF THE FLORIDA MANATEE (TRICHECHUS-MANATUS LATIROSTRIS)

The use of perioral bristles (modified vibrissae) by 17 captive Florid a manatees and approximately 20 wild manatees was analyzed. Captive ma natees were fed six species of aquatic vegetation normally eaten in th e wild (four freshwater species and two seagrasses). Inanimate objects were placed in the holding tanks with manatees at Lowry Park Zoologic al Gardens (Tampa, FL) to determine the degree to which perioral brist les were used in exploration and to define the range of manipulative b ehavior. In addition, behavioral observations were made on the use of perioral bristles during social interactions with conspecifics. Observ ations were recorded using a Hi8-format video camera. Florida manatees possess an unusually large degree of fine motor control of the snout and perioral bristles. The large and robust perioral bristle fields of the upper lip were used in a prehensile manner during feeding. Bristl e use by manatees feeding on submerged vegetation differed from that s een during feeding on floating vegetation. Other behavioral use of the perioral bristles shows variation depending upon the situation encoun tered. The degree of plasticity of perioral bristle use supports our h ypothesis that the vibrissal-muscular complex of the Florida manatee h as evolved to increase the efficiency of grazing and browsing on aquat ic vegetation and to fully maximize the potential of the manatee as a generalist feeder. The manipulative and sensitive nature of the manate e snout is likely a manifestation of a complex sensory and motor syste m which has evolved for marine mammal aquatic herbivores living in sha llow turbid habitats.