Whales are marine mammals and like all mammals they require air to breathe and must come to the surface of the water to take in oxygen.
Unlike fish these marine mammals are not equipped with gills, which fish and other aquatic animals use to extract oxygen from water; Instead whales need to rise to the surface of the water to inhale and exhale oxygen through their blowholes.
When it comes to anatomy all species of whale are broken down into two suborders based on their physical features.
These two suborders are known as the toothed whale and baleen whale suborders.
Baleen whales which have baleen plates and are the larger of the two suborders are born with two blowholes that they use for breathing while toothed whales which are smaller and have teeth are born with a single blowhole.
Note: Some theorists believe that the toothed whale suborder developed one of their blowholes into an echolocation system in order to help them navigate the ocean and locate prey.
Blowholes and Breathing
In order to make it easier to breath the whales blowhole(s) are located at the top of the whales head and act as a passageway to the trachea where air passes through the air passage and fills the lungs.
Having their blowhole on the top of their head makes it easier for them to breathe with minimal effort, especially during times of rest when they can be seen logging around near or at the surface of the water.
While whales are known to breathe through their blowholes they are unable to breathe through their mouth because the trachea is not connected to the whales throat.
This separation is important for a number of reasons.
First having a separate hole for breathing and eating allows whales to minimize the likelihood of blocking their air passage due to food trapped in their throat.
More importantly having a separate air passage and food passage means that whales are able to swallow their food underwater without worrying about taking water into their lungs as most mammals risk opening the air passage to their lungs when they eat.
If a human were to try and consume food underwater there is a chance that their nostrils or air passage would open up causing their lungs to take in water.
Additionally by having the blowhole situated on the top of the whales head they can take in oxygen without having to lift their head above the water or exert additional energy.
Diving
To assist with long dives whales have developed special lungs that help them inhale additional oxygen and transfer it to enlarged blood vessels where it can be used by the body.
According to some researchers whales are also able to use up to 90% of the oxygen they inhale as compared to humans that are only able to use around 15% of the oxygen they inhale.
Whales are also extremely efficient swimmers and use minimum effort to travel and hunt for food in order to conserve precious oxygen.
In terms of how long a whale can hold its breath varies depending on the species of whale.
Some species can only hold their breath for only a few minutes before resurfacing for air while other whales can hold their breath for up to 90 minutes or more.
Due to the fact that whales live in the ocean they’ve developed a way to maintain their awareness of their surroundings and maintain control of their breathing, even when at rest.
In fact whales are considered conscious breathers because they never fall completely asleep and they must frequently come up for air otherwise they could drown and die.
During periods of rest half of the whales brain will shut down while the other half of their brain remains alert in order to react quickly to life-threatening situations such as resurfacing for oxygen or running from predators.
When a whale surfaces from a long dive it is common to see water spouting from the whales blowhole which is a sign that the whale is exhaling.
In the past people thought that the water coming from the blowhole was water that the whale swallowed or inhaled, however this is not the case because if a whale inhaled the water it would likely enter their lungs and the whale would drown, and since the throat is not connected to the blowhole it is virtually impossible for a whale to spurt out water that it swallowed through its mouth.
The water that spouts from the blowhole is simply water that has collected around the outside of the blowhole.
The whales blowhole is surrounded by muscles to allow the whale to dive without fear of taking in water.
Researchers are unsure of whether or not whales swallow large amounts of water when they engulf their food due to the high concentration of salt in the salt water, however some species are known to expel the excess water by pushing it out of their mouth with their tongue, while simultaneously keeping their food trapped inside the baleen plates, so it quite possible that much of the water whales engulf comes from the water contents of the food they swallow rather than being consumed directly, since much of their food contains water within its body.
In order to manage their salt intake whales likely have specialized livers and urinal systems to help them remove excess salt from their body when they swallow their food and/or water due to the fact that most mammals would suffer from numerous issues if they consumed too much salt such as becoming dehydrated, issues hallucinations, kidney damage and even death.
Dolphins and Porpoises
In addition to the whale species dolphins and porpoises are also marine mammals and must rise to the surface to obtain oxygen.
In fact all three types of marine mammals belong to the cetacean family and share a number of physiological traits with one another including having blowholes, breathing oxygen, maintaining constant awareness of their breathing and being able to dispose of additional salts that are taken in by their body when they consume food.
As marine mammals they are also warm-blooded animals that give birth to their young and produce milk to feed their babies.