Narwhals are unique Arctic whales best known for their long, spiraling tusks. These elusive creatures spend much of their lives underwater, surfacing occasionally to breathe. But how exactly do narwhals breathe? Here is an in-depth look at the narwhal’s respiratory system and breathing adaptations.
How Do Narwhals Breathe?
Like all mammals, narwhals are air-breathing creatures. Narwhals breathe air at the water’s surface through a nostril called a blowhole located on top of their head, just like other whales and dolphins. This allows them to fulfill their oxygen needs while living fully aquatic lives.
Their ability to hold their breath for up to 25 minutes enables prolonged dives to extreme Arctic depths.
A narwhal’s breathing sequence goes as follows:
- The narwhal surfaces with just its blowhole exposed. It exhales stale air from its lungs through the blowhole, forming a spout shape.
- Next, The narwhal opens its blowhole and takes a deep breath of fresh air down its windpipe and into its lungs for up to several seconds.
- Its muscular flap closes to seal off the blowhole as the narwhal prepares to dive.
- While underwater, oxygen is steadily depleted from the lungs and bloodstream.
- Before oxygen runs out, the narwhal returns to the surface to breathe again. It repeats this cycle of breathing followed by diving continuously.
How Often Do Narwhals Come Up For Air?
As mentioned, narwhals can hold their breath for up to 25 minutes while diving underwater. However, most dives last 3-8 minutes. Narwhals often make a series of shorter, shallow dives interspersed with brief surfacing to breathe. This breathing pattern varies based on what the narwhal is doing – traveling, hunting, socializing, etc.
Mother narwhals may alter their surfacing time when caring for their calves. Newborn calves lack the muscle and oxygen storage capacity to stay underwater for more than a few minutes. They must surface as often as every 1-3 minutes. The mother narwhal matches her baby’s surfacing rate so the pair does not become separated. As a calf matures over its first year, it builds endurance and can stay underwater longer.
How Deep Can Narwhals Dive While Holding Their Breath?
The maximum recorded dive depth for a narwhal is 1,500 meters (4,900 feet). This makes them among the deepest diving whales. However, dives to such extreme depths are unusual. Most narwhals spend their time much closer to the surface:
- Shallow dives: 300 – 600 feet.
- Common depth range: 600 – 3,300 feet.
- Maximum recorded: 4,900 feet.
Deep dives may be performed during mating and migration seasons. For routine activities like hunting and socializing, narwhals favor shallower depths. By diving moderately deep but frequently resurfacing, narwhals can balance meeting their oxygen needs and avoiding hazards of extreme depths.
Do Narwhals Sleep and How Do They Breathe?
Yes, narwhals do sleep, but they have developed a unique way of sleeping that allows them to continue breathing.
Narwhals need to surface regularly to breathe air through their nostrils. Since they are conscious breathers, they cannot hold their breath indefinitely while sleeping like some whales.
Instead, narwhals sleep with only half their brain at a time, a strategy called unihemispheric slow-wave sleep. This allows them to continue swimming to the surface to breathe periodically, with one half of their brain awake, while the other half rests. This type of sleep has been observed in other marine mammals like dolphins.
Some key points about how narwhals sleep and breathe:
Narwhals sleep in short bursts of 10-30 minutes with half their brain at a time. This ensures they can still navigate to the surface to breathe. During this time, they continue slow pectoral fin movements to maintain buoyancy.
While they sleep, they swim near the surface in a horizontal position. They keep their blowhole above water to breathe.
Their unihemispheric sleep pattern means different brain hemispheres rest in cycles. So, they are always partially alert and able to swim and breathe.
How Do Narwhals Breathe When Surfaces Are Frozen?
In the winter, narwhals face an additional challenge – thick, frozen Arctic surfaces. Narwhals rely on small temporary cracks and lead in the ice to access the air above. They also use their tusk to enlarge small breathing holes or smash through thin ice when necessary.
Narwhals may also take advantage of tide cracks, polynyas, or areas of thin ice over deep water. Here are some of the strategies researchers have observed narwhals using to breathe in icy conditions:
- Following the edges of large cracks and openings.
- Finding areas where currents or upwellings prevent ice from fully forming.
- Breaking thin ice sheets with forceful body movements.
- Using vocalizations to maintain openings in the ice.
- Repeatedly circling openings to keep them from freezing over completely.
- Blowing bubbles to push back against forming ice layers.
- Poking existing holes with their tusk to keep them open.
- Relying on openings formed by other marine mammals like seals.
Narwhals are capable of sensing just how thick ice is using echolocation. This helps them identify areas where it is possible to create or enlarge breathing holes. Their extreme diving abilities allow them to survive if breathing holes become few and far between.
How Do Narwhals Breathe During Their Migrations?
Narwhals make annual migrations as the winter sea ice forms and break up. During migration, they must adapt to various ice conditions along their route.
In the late summer and fall, thousands of narwhals migrate from open water summering grounds to deep water wintering areas. At this time, they can surface freely over open water.
As winter sea ice forms, narwhals become entrapped in dense, unbroken pack ice. They use specialized ice entrapment and acoustic behaviors to cope as mentioned above.
In the spring, narwhals rely on leads and shrinking areas of thin ice to breathe. As the ice breaks up, they can once again make more regular deep dives under open water. Flexibility in their breathing strategy allows narwhals to survive the extreme seasonal changes of the Arctic.
The Risks Narwhals Face When Breathing on the Surface
There are some risks associated with how narwhals breathe and surface to inhale air.
- Surface breathing makes them vulnerable to hunting. In the past, narwhals were hunted extensively by Inuit and European whalers near the surface as they exhaled from their blowholes. Overhunting dramatically reduced some populations. Strict hunting limits are now in place.
- Being reliant on surfacing means they can potentially be injured or drowned by ship strikes if they are unable to surface quickly. Increased shipping in Arctic waters due to less sea ice poses a threat. Source
- Loud noises from seismic airgun blasts used in oil and gas exploration and from ships disrupt narwhals. This makes them come to the surface too soon, which interrupts their feeding and makes them more likely to be attacked by predators. This wastes energy stores.
- Climate change impacts like less sea ice and warmer waters disrupt their habitat and prey availability. This forces them to use more energy diving deeper for food, increasing risks of decompression sickness if surfacing too fast.
So in summary, surface breathing and reliance on surfacing. This makes narwhals vulnerable if unable to surface or if disrupted by natural behaviors like feeding and resting. Human impacts and climate change introduce risks.
Frequently Asked Questions
Do Narwhals Have a Blow Hole?
Yes, narwhals do have a blowhole. Like whales, dolphins, and porpoises, narwhals breathe air through a single blowhole located on the top of their head. The blowhole is a modified nostril that can be closed tightly when the narwhal is diving underwater.
Do Narwhals Have Lungs?
Yes, narwhals have lungs. As air-breathing marine mammals, narwhals have lungs that allow them to breathe oxygen from the atmosphere. Their lungs are similar in structure and function to human lungs. When at the surface, narwhals inhale through their blowhole, drawing air down the trachea and into the lungs.
Can Narwhals Drown?
Yes, narwhals can potentially drown. While narwhals have advanced dive physiology, they remain at risk of drowning if unable to access the surface to breathe through their blowhole regularly, such as due to entanglement, trapping under ice, or disruption of natural surfacing patterns.