The moose (Alces alces) is widely recognized as the largest member of the deer family, a massive herbivore that primarily inhabits the boreal forests of the Northern Hemisphere. Despite its considerable size and terrestrial appearance, this ungulate possesses a remarkable, often surprising affinity for water. Moose are exceptional swimmers, capable of covering great distances and frequently utilizing aquatic environments for survival and foraging. This highly capable aquatic behavior involves the unique ability to fully submerge their bodies and hold their breath beneath the surface.
The Aquatic Environment and Moose Diet
The motivation for a moose to hold its breath and dive is rooted deeply in its nutritional requirements, particularly during the warmer months. Terrestrial plants, which make up the bulk of its diet, often lack sufficient amounts of sodium, a mineral frequently concentrated in aquatic vegetation. To compensate for this deficiency, moose seek out submerged plants like pondweed and water lilies, which can contain four times the mineral content of land-based browse.
This foraging strategy requires the animal to spend significant time submerged to reach the most nutritious parts of the plants. Aquatic plants are also highly digestible, making them an important and energy-efficient food source during the summer.
Maximum Submergence Time
The duration for which a moose can remain underwater varies depending on the animal’s age, the depth of the dive, and its immediate motivation. In typical foraging situations, an adult moose will submerge its head and body for an average duration of 20 to 30 seconds. This is often enough time to grasp a mouthful of aquatic plants before resurfacing for air.
When necessary, a moose can sustain much longer periods beneath the surface. Observations indicate that an adult can comfortably hold its breath for approximately one minute when diving to feed or escape danger. Exceptional instances have been recorded where a mature moose has remained submerged for up to 90 seconds.
The length of the dive is highly influenced by the depth of the water and the location of the food source. Moose have been known to dive over 5.5 meters (18 feet) to reach plants on the lake bottom. Younger calves, with smaller lung capacities, generally sustain dives for shorter periods, typically between 30 and 60 seconds.
Physical Adaptations for Diving
The ability of the moose to perform these impressive dives is supported by a suite of physical and physiological adaptations. The moose possesses large, muscular nostrils that are valve-like and can be closed tightly when the animal submerges. This mechanism prevents water from entering the respiratory system, allowing for focused foraging activity.
Moose also possess a large lung capacity, which allows them to take in and store a substantial volume of oxygen before a dive. Furthermore, like other diving mammals, they exhibit the mammalian dive reflex, which includes a temporary slowing of the heart rate to conserve oxygen during submergence. This physiological response directs oxygenated blood flow primarily to the brain and other critical organs.
Their long, powerful legs, which are excellent for navigating deep snow, also serve as strong paddles for propulsion and maneuvering underwater. The coat consists of long guard hairs that are hollow and trap air, providing a significant degree of buoyancy. While this buoyancy requires the moose to exert effort to remain submerged, it aids in rapid resurfacing and provides insulation in cold water.