Sperm whales have one of the most unusual sleeping behaviours; they rest while floating vertically underwater, with their heads pointing downward and their bodies almost motionless.A new study published in the Journal of Experimental Biology has found that all the whales released bubbles during their resting dives.
"While resting, sperm whales release bubbles, hypothesised to help them regulate their buoyancy," the study read.Sperm whales are breath-hold divers, which means they store air in their bodies before making long underwater dives.
When a resting whale slowly drifts upward, the gas inside its lungs expands because the pressure of the water decreases.
This could make the whale too light and force it to rise towards the surface.
They also believe that bubbles may help whales release extra gases like carbon dioxide or nitrogen that build up in their bodies during long dives.
Sperm whales have one of the most unusual sleeping behaviours; they rest while floating vertically underwater, with their heads pointing downward and their bodies almost motionless.A new study published in the Journal of Experimental Biology has found that all the whales released bubbles during their resting dives. The simulation confirmed that the bubble release helped them regulate their buoyancy and remain underwater while sleeping.Researchers created a computer simulation using details such as the whale's body density, resistance from water and the amount of gas stored inside its body. They compared the results with data collected from 10 tagged sperm whales in Norway that rested mainly by diving head-down.Researchers also believe the position helps protect the whales from strong surface waves while saving the energy they would need to move to deeper waters.But scientists were especially curious to find out why sperm whales release bubbles while resting.The study found that every sperm whale that was resting underwater released bubbles, which help whales control their buoyancy, or their ability to float and stay at a particular depth."While resting, sperm whales release bubbles, hypothesised to help them regulate their buoyancy," the study read.Sperm whales are breath-hold divers, which means they store air in their bodies before making long underwater dives. When a resting whale slowly drifts upward, the gas inside its lungs expands because the pressure of the water decreases. This could make the whale too light and force it to rise towards the surface."Releasing bubbles would enable them to counteract the expanding diving gas and achieve neutral buoyancy," the study read.Researchers also discovered that before starting a resting dive, sperm whales carry less air in their lungs compared with when they dive deep to hunt for food.However, scientists say there could be another reason for the bubbles. They also believe that bubbles may help whales release extra gases like carbon dioxide or nitrogen that build up in their bodies during long dives."We cannot rule out the possibility that releasing bubbles is related to the offgassing of excess CO2 or N2 from tissues into the lungs, so this behaviour could also have implications for metabolic gas exchange," the study read.
