Manatee Vibrissae ? A Mammalian Lateral Line?

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Endangered Florida manatees have a number of unusual anatomical and behavioral adaptations related to their unique role as mammalian aquatic herbivores. Chief among these is the presence of sensory hairs over the entire body, whereas in most mammals these are only present as facial whiskers. The present research uses two captive manatees at Mote Marine Laboratory to assess the ability of this system of specialized hairs to detect water-borne vibrations associated with other moving animals, river currents, and tidal flows, all of which are cues likely to be used in navigation. This research relates not only to the normal behavior of manatees, but also to their ability to detect and avoid approaching boats. These two animals have been trained on a number of related tasks and are able to report behaviorally whether a stimulus has been detected. It will be possible to determine the range of frequencies and amplitudes to which the animals are capable of responding, and their degree of directional localization ability. It will also be possible to discover whether certain portions of the body are more sensitive than others. Anatomical experiments on postmortem brains will be performed at the University of Florida to map the neural connections that mediate these abilities. This work utilizes special fluorescent tracers that travel down nerve fibers by diffusion over a period of several months. In addition, a significant portion of this project includes educational interactions with students and teachers at Mote, New College, the University of South Florida, and the University of Florida.