Why does the sperm whale secrete gas bubbles while sleeping vertically?
When it comes to marine life, there are facts beyond human imagination. In the latest findings, scientists have discovered a lesser-known fact about sperm whales and their resting mechanism.
According to them, sperm whales have a wonderful way of resting far beneath the ocean waves. Researchers from the University of St Andrews and the University of Neuchâtel have provided a rare look into the secret life of one of the ocean’s largest and most intelligent marine animals. Scroll down to read the details.
What does the research say?
The research found that unlike most marine mammals, sperm whales sleep in a strange upright position, swaying almost motionless under the surface of the sea.
Experts have revealed the interesting mechanism they use to maintain this strange sleeping position: they release a gas bubble to regulate their buoyancy, allowing them to remain suspended in the water.
What is this unique sleeping position and its benefits?
What is this unique sleeping position and its benefits?
You will be surprised to know that sperm whales are the only known species of whales that routinely sleep in an upright position. They spend these rest periods suspended vertically in the water column, often with their heads pointing toward the surface and their bodies rolling downward.
According to researchers, this sleeping position has many benefits. Whales stay close to the surface so they can breathe easily when they wake up, and the upright position may protect them from the action of ocean waves.
It may also help them avoid the energy drain caused by drifting into deeper water.
Difficulty staying suspended
Scientists have found that sperm whales suffer from a strange buoyancy problem and that their large heads contain a special organ filled with a waxy substance called sperm oil that helps them float naturally.
They are naturally positively buoyant, meaning they tend to rise toward the surface. They are also animals that dive into the depths and hold their breath. So, when they dive and hold their breath, the gases in their lungs change as the pressure increases and decreases.
When they rest near the surface, the gas in their lungs slowly expands, increasing their chances of ascending. Sperm whales deal with this by releasing small amounts of gas, in the form of bubbles, which helps them control their buoyancy and float in an almost weightless state.
How did scientists discover this?
Understanding the mechanism of sperm whale sleep
For the purposes of this analysis, the researchers placed small sticky tags on sperm whales off the coast of Norway to collect data. The benign tags recorded the whales’ movements and sounds in detail as they rested and moved through the ocean. The tags also recorded clear bubble-releasing sounds during the whales’ rest periods. When scientists combined this audio information with movement data, it helped them reveal the unique resting style of sperm whales, much to their surprise.
The results duly showed that releasing bubbles helped the whales overcome their natural buoyancy and remain suspended below the surface, near neutral buoyancy.
How do they manage this control?
The most surprising finding in this research is that sperm whales appear to be able to make subtle adjustments to buoyancy while they sleep. Professor Patrick Miller, from the Marine Mammal Research Unit at the University of St Andrews, said: “Sperm whales have an amazing ability to control their buoyancy by emitting gases when they are at rest.
“Such fine adjustments during sleep are behaviorally very different from anything seen in terrestrial mammals, including us,” he added.
The study also revealed that sperm whales’ resting dives begin with a lower gas volume than their dives at greater depths while actively hunting for food, and this difference allows them to maintain a stable position during sleep.
Possible association with gas exchange
Possible association with gas exchange
According to scientists, the law of bubble release may have another vital role. It is thought that it may have something to do with the removal of excess carbon dioxide or nitrogen from the body’s tissues into the lungs. If the discovery is confirmed, it could provide new insights into how sperm whales deal with the physical stresses of deep diving, breath holding, and sleeping underwater.Images courtesy of: iStock and Journal of Experimental Biology
