Manatees, often called sea cows, are large, gentle marine mammals known for their slow, peaceful movements and herbivorous diet. These aquatic giants typically weigh between 800 and 1,200 pounds and spend their lives grazing on seagrass and other vegetation in shallow, warm waters. This article explains the science behind the manatee’s fully aquatic existence and the physical reasons why they must remain in the water.
Are Manatees Able to Leave the Water
Manatees are obligate aquatic mammals, meaning they are biologically required to live in water and cannot safely come onto land for any sustained period. While they can raise their heads onto shallow banks or briefly use their flippers to push themselves along a river bottom, they lack the skeletal and muscular structure for terrestrial locomotion. Their biology is fine-tuned for a weightless, submerged environment. A manatee found out of the water is almost always a sign of an emergency.
Aquatic Adaptations and Physical Limitations
The manatee’s inability to support its massive body on land is rooted in a unique skeletal adaptation known as pachyostosis. This condition involves the thickening and densification of the bones, particularly the ribs, which lack a marrow cavity. This heavy, solid bone structure acts as a ballast, helping the manatee maintain neutral buoyancy while grazing on aquatic plants. This immense skeletal weight becomes a profound disadvantage when gravity is no longer counteracted by water.
The manatee lacks the bony structures necessary for walking. They possess only vestigial pelvic bones, which are not connected to the vertebral column and serve as attachment sites for some muscles. This absence of a pelvic girdle means the spine cannot bear the load of their body weight, risking the crushing of internal organs if they were on land. Their flippers are adapted for steering and scooping food, not for supporting thousands of pounds on a hard surface.
The manatee’s skin and physiology are ill-equipped for a terrestrial environment. They have a high lower critical temperature, meaning they are sensitive to cold and require water above 68°F (20°C) to avoid cold stress syndrome. On land, they would quickly face overheating and rapid dehydration, as their skin is not designed to retain moisture or efficiently regulate temperature in the open air. Unlike many other marine mammals, they lack a thick layer of insulating blubber.
Stranding and Emergency Response
When a manatee is found on land, it is typically a stranding event caused by factors like extreme low tides, injury, or disorientation. The dangers include dehydration, exposure, and organ damage from the unsupported weight pressing against the ground. Due to their dense bones and large mass, the pressure exerted by their body on internal tissues can quickly become life-threatening.
If a stranded manatee is discovered, the public should never attempt a rescue or push the animal back into the water. Instead, contact the local wildlife authority or the Florida Fish and Wildlife Conservation Commission (FWC) at 1-888-404-3922. While waiting for authorized teams to arrive, the manatee should be kept wet with water from a hose or bucket and shaded to prevent overheating.
Rescue teams, part of the Manatee Rescue and Rehabilitation Partnership, use specific protocols to handle these animals. They transport manatees on specialized foam pads to evenly distribute the body weight, mitigating the risk of organ damage. The animals are moved in climate-controlled trucks to authorized acute care facilities for rehabilitation before release back into the wild.