Food-Handling Ability and Feeding-Cycle Length of Manatees Feeding on Several Species of Aquatic Plants

Food-handling ability was examined in Florida manatees (Trichechus manatus latirostris) feeding on different species of aquatic plants during controlled feeding trials. Subjects were presented with freshwater (Hydrilla verticillata, Myriophyllum spicatum, and Vallisneria americana) and marine species (Syringodium filiforme and Thalassia testudinum) of aquatic plants. Food handling was quantified by measuring length of cyclic movements (or feeding cycles) of perioral bristles that manatees use to introduce food into the mouth. Mean feeding-cycle lengths varied, depending on body size of the subject and species of plant being consumed. Rates of food introduction derived from mean feeding-cycle lengths were similar to chewing rates reported by other researchers. Manatees consumed plants with tubular stems and numerous branches faster than plants with flat blades. Food-handling time using perioral bristles differed, depending on the species of plants consumed and was reflected in the mean feeding-cycle length.