Whales are fascinating creatures in many ways. For example, the blue whale is the largest creature that has ever lived, larger than the biggest dinosaur. One of the interesting feats of whales is their ability to stay underwater for a tremendous amount of time. How do they do this?
There are records of whales diving to the depth of over 2,000 feet. That is an enormous accomplishment. At that depth, a man must be contained in a pressurized environment because they’d otherwise be crushed from the pressure. What’s more, whales often spend in excess of a half-hour underwater. There are records of harpooned whales staying underwater for as long as two hours. Whales are air-breathing mammals just like you and me. How do they hold their breath that long?
The answer is that they don’t. When a whale dives, most body functions nearly stop. The heart-rate goes way down, digestion and respiration cease altogether and what little blood flow there is mostly for the brain and muscles. However, they still need oxygen to survive and they don’t have the means of getting it from ocean water. Here is where it gets interesting.
You probably know what hemoglobin is. This is a protein in red blood cells that binds with oxygen and carries the oxygen to every living cell in the body. However, there is a similar protein that is found in all mammals, actually in all vertebrates, called myoglobin. Myoglobin doesn’t have a role in the transport of oxygen, rather, it stores oxygen within muscle tissue. In fact, the medical prefix ‘myo-‘ means “muscle”. It is myoglobin that gives red meat the red color and makes muscles red.
It is myoglobin that allows endurance runners to run as long as they do without collapsing. Hemoglobin simply can’t supply the oxygen needs in a situation like this. So the muscles start using the oxygen stored by myoglobin in the human body, during such high-stress times.
As it turns out, deep-diving whales have a huge amount of myoglobin in the muscles of their body. They have 8 to 9 times more myoglobin than a typical person does. While myoglobin is responsible for the red color of muscle tissue of land animals, a whale has so much myoglobin that the muscles are nearly black in color.
It is from the storage of oxygen in myoglobin that whales are able to stay underwater from 30-120 minutes. A typical human has difficulty holding their breath for 2-4 minutes, for comparison. Being able to refrain from breathing for that long is what allows whales to dive to the depths they are capable of, at pressures that would crush their lungs if they tried doing it with a lungful of air.
Do you agree that this is an amazing adaptation?
Did you previously know about myoglobin and how come whales are able to stay underwater so long?
I knew about myoglobin, but not about whales
I knew about whales, but not myoglobin