Diving and foraging behaviors

Abstract

Manatees and dugongs live in tropical and semi-tropical regions around the world. Their preferred habitats are seagrass beds, rivers, lakes, and estuaries. Manatees live in both freshwater and marine systems although habitat preferences vary across the three species, while the dugong is entirely marine. Sirenians are shallow water divers, and their dive durations are short compared to most other marine mammals. The maximum recorded manatee dive duration is 24 min, with the maximum recorded duration of a dugong dive being about half that. Even though the durations of dugong dives are shorter than those of manatees, current data indicate that dugongs dive deeper than manatees. Dive depths for manatees generally do not exceed 5 m, other than during occasional travel over deeper water; however, this may be an artifact of water depth in areas where diving data were recorded, or where manatees live. In some parts of their range, dugongs are found over deep-water seagrass beds and dives have been recorded to more than 30 m. All extant sirenians eat diverse plant-based diets: collectively they have been documented feeding on at least 55 genera of marine and freshwater plants. Although not confirmed for the Amazonian manatee, it is likely that all extant sirenians eat animal, as well as plant, matter. West Indian and African manatees have been documented eating marine and freshwater fish and invertebrates , and for African manatees, these food resources are a regular part of their diet, arguably making them omnivores . Dugongs have been recorded targeting invertebrates at the high latitude limits of their range in winter. All manatees like to drink fresh water, in contrast to dugongs, which live entirely in marine systems and apparently meet the water requirements from their food.