Manatees, often called “sea cows,” are large, gentle aquatic mammals known for their slow-moving nature and herbivorous diet. They navigate various aquatic environments. Understanding their habitat preferences and adaptations provides insight into their survival.
Manatee Habitats
Manatees adapt to different water types, with some species inhabiting saltwater, freshwater, and brackish environments. Brackish water is a mixture of fresh and saltwater, commonly found in estuaries where rivers meet the sea. This flexibility allows them to access diverse food sources, such as seagrasses in marine environments and various aquatic plants in freshwater systems. Their ability to move between these water types also provides opportunities for refuge or warmer waters during colder periods.
The West Indian (including Florida manatee) and West African manatees thrive in all three water types. They are frequently found in shallow rivers, bays, canals, estuaries, and coastal areas. In contrast, the Amazonian manatee lives exclusively in freshwater habitats within the Amazon Basin. This species primarily inhabits slow-moving rivers, floodplains, and lakes rich in aquatic vegetation.
Adapting to Water Salinity
Manatees manage varying salt concentrations through physiological mechanisms. Osmoregulation involves their kidneys filtering blood to maintain internal water and salt balance, concentrating urine to retain fresh water even in saltwater.
Manatees spend extended periods in saltwater but do not actively drink it. They obtain water from plants and by periodically seeking freshwater sources. Manatees in saltwater may need freshwater or brackish water every one to two weeks for hydration. Deprived of freshwater, they show signs of dehydration and may stop feeding.
Global Distribution and Specific Needs
Manatee distribution is influenced by environmental requirements, particularly water temperature and freshwater access. West Indian manatees are found along the southeastern United States, throughout the Caribbean, Mexico, Central America, and northern South America. These manatees prefer waters above 21°C (70°F) and migrate to warmer areas, such as natural springs or power plant outfalls, when water temperatures drop below 20°C (68°F).
Amazonian manatees are restricted to the Amazon Basin, spanning countries like Brazil, Colombia, Ecuador, and Peru, where they inhabit rivers and floodplain lakes with water temperatures typically ranging from 25°C to 30°C (77°F to 86°F). West African manatees live along the western coast of Africa, from Senegal to Angola. They occupy a wide range of habitats, including oceans, rivers, lakes, and coastal estuaries, generally avoiding waters below 18°C (64°F). Seasonal movements for both Amazonian and West African manatees are often tied to water levels and the availability of food and freshwater sources.