Manatees, often called “sea cows,” are large, gentle aquatic mammals found in shallow coastal waters, estuaries, and rivers. These slow-moving herbivores spend much of their time grazing on aquatic vegetation. Their adaptations allow them to thrive in both freshwater and saltwater habitats.
The Basics of Manatee Breathing
Manatees must surface to breathe air. While resting submerged, they typically surface every three to four minutes. When active, such as during swimming or feeding, their breathing frequency increases, requiring them to surface as often as every 30 seconds. They breathe through nostrils on top of their snouts, which close tightly underwater. Upon surfacing, they quickly exchange air, often exposing only their nostrils.
Factors Influencing Breathing Frequency
A manatee’s breathing frequency varies based on its activity level. When resting, a manatee can hold its breath for up to 20 minutes, sometimes even 24 minutes. During higher exertion, like active swimming or foraging, the need for oxygen increases, prompting more frequent surfacing to meet metabolic demands.
Environmental conditions also influence breathing. Water temperature affects their metabolic rate; in colder waters, manatees may conserve energy, impacting diving patterns. Manatees prefer shallower waters, typically three to seven feet deep, where surface access is readily available. Stress levels, age, and overall health also impact breath-holding ability.
Underwater Breathing Adaptations
Manatees have several physiological and anatomical adaptations for their aquatic lifestyle and extended breath-holding. Their large, flattened lungs extend horizontally, distributing buoyant forces evenly and helping them maintain a horizontal orientation. Unlike humans, manatees have two “hemi-diaphragms,” enhancing efficient air exchange.
With each breath, manatees exchange about 90% of the air in their lungs, significantly higher than the 10% for humans. This efficient gas exchange supports longer underwater durations. Their nostrils have muscular valves that seal tightly underwater, preventing water entry. Additionally, manatees can slow their heart rate while diving, known as bradycardia, conserving oxygen for vital organs.
The Importance of Breathing for Manatees
Beyond obtaining oxygen, the manatee’s respiratory system is integral to its buoyancy control. Their large lungs function like a flotation device, allowing them to adjust their position in the water column. By compressing or expanding their lungs, they can increase or decrease their body density, enabling them to sink for feeding or resting, or rise to the surface for air. This control is fundamental for feeding on submerged vegetation and moving through varying depths.
Access to the water surface is necessary for manatee survival. As obligate air-breathers, any obstruction to surfacing poses a serious threat. This makes them vulnerable to boat traffic, as they must frequently rise to breathe. Their need for unobstructed surface access underscores the importance of human awareness and conservation efforts in shared aquatic environments.