Ducks are commonly observed on and around water, often submerging themselves. A common question arises regarding their ability to breathe underwater. Ducks do not possess gills like fish, and therefore cannot extract oxygen from water. Instead, they rely on atmospheric air for respiration, just like other land animals.
Why Ducks Cannot Breathe Underwater
Ducks are air-breathing vertebrates, equipped with lungs for respiration. Their respiratory system takes in oxygen from the air and releases carbon dioxide, a process requiring an atmospheric environment. Unlike aquatic organisms such as fish that use gills to absorb dissolved oxygen from water, ducks cannot survive indefinitely submerged.
The avian respiratory system is highly efficient, featuring a unique unidirectional airflow through their lungs and a series of air sacs. This system ensures a continuous supply of fresh oxygen, beneficial for high-energy activities like flight. However, this specialized system depends on air availability. When a duck dives, it must hold its breath, relying on the oxygen it took in before submerging.
How Ducks Survive Underwater
While ducks cannot breathe underwater, they possess remarkable adaptations that enable them to spend time submerged effectively. They can hold their breath, with typical dives lasting between 10 to 30 seconds. Some diving duck species can remain underwater for a minute or more, and exceptional cases, like the Long-tailed Duck, have been recorded holding their breath for several minutes.
During a dive, ducks exhibit a physiological response known as the “diving reflex.” This reflex, often triggered when water touches their nostrils, involves a significant slowing of the heart rate, called bradycardia. Concurrently, blood flow is redirected, ensuring vital organs like the brain and heart receive adequate oxygen, while blood flow to less critical areas is curtailed. Ducks also have muscles rich in myoglobin, a protein that stores oxygen, further enhancing their capacity for prolonged underwater activity.
Physical adaptations also play a role in their underwater survival. Their dense, waterproof feathers trap a layer of air close to their bodies, providing insulation. To facilitate diving, ducks can compress these feathers, squeezing out trapped air to reduce buoyancy and make submerging easier. They can also close their nostrils to prevent water from entering their respiratory passages. Furthermore, ducks have vision adapted for seeing clearly underwater, which assists them in navigating and locating items.
Reasons Ducks Dive
Ducks engage in underwater activity primarily for two main reasons: foraging for food and evading predators. Many duck species search for aquatic plants, invertebrates, and small fish beneath the surface.
Ducks are broadly categorized into dabbling ducks and diving ducks, reflecting their distinct feeding strategies. Dabbling ducks typically feed by tipping their bodies forward, reaching for food just below the water’s surface while keeping their tails in the air. In contrast, diving ducks fully submerge themselves, propelling themselves with their powerful webbed feet and sometimes their wings, to access food in deeper waters or on the bottom. This distinction in feeding behavior shapes their physical characteristics, with diving ducks often having legs set further back on their bodies for more efficient underwater propulsion.
Beyond foraging, diving serves as an effective defense mechanism. When faced with a threat, ducks can quickly dive underwater to escape, using the water as a protective barrier against airborne or land-based predators. This allows them to disappear from sight, often resurfacing some distance away from their initial dive point.