Buzz
By Chris Gayomali
Marine mammals boast numerous remarkable traits that allow them to thrive underwater, such as flippers and a layer of insulating blubber. Whales also possess eyes that can see in black and white, a useful feature in the deep, light-deprived waters where sunlight is scarce.
One of the most remarkable features of whales is their extraordinary ability to hold their breath for as long as an hour. Scientists believe this is due to their high levels of myoglobin, a molecule found in blood that helps muscles retain oxygen. While myoglobin is responsible for the red color of meat in creatures like cows and humans, seals and whales have an exceptionally high concentration of this molecule, which gives their tissues a black appearance.
Zoologist Michael Berenbrink, a researcher at the University of Liverpool, found this quite unusual. "At high enough concentrations, [proteins] tend to stick together," Berenbrink tells BBC News. When too many proteins clump together, they become ineffective—essentially dead weight.
So, how do the densely packed myoglobin molecules in marine mammals avoid sticking together? BBC News reports:
The research team isolated pure myoglobin from the muscles of various mammals—from the land-dwelling cow to the semi-aquatic otter, and even elite divers like the sperm whale. Under the leadership of Scott Mirceta, this thorough study traced myoglobin's evolution in deep-diving mammals over a span of 200 million years. The findings revealed that the best breath-holding divers evolved a special non-stick version of myoglobin. [BBC News]
The solution, it seems, is that marine animals' myoglobin is positively charged, similar to one end of a magnet. Instead of sticking together, the molecules repel one another, keeping the blood fluid and well-lubricated.
The whale's ability to hold its breath represents an evolutionary advantage: (1) The high concentration of myoglobin lets it stay underwater longer between breaths, and (2) the positive charge of the myoglobin prevents the proteins from clumping and harming the animal. Researchers suggest that mimicking this natural process could influence medical practices, especially in the area of human blood transfusions.
Berenbrink and his team even went as far as reconstructing the myoglobin sequences of the whale's ancestors to identify when this evolutionary trait might have developed. "If you give me a myoglobin sequence, I can tell you if the animal is a good diver or not," Berenbrink explains to Nature:
By using the reconstructed sequences from various animals to estimate the electric charge of their myoglobin, alongside data on the animal's body mass, the team concluded that an early whale ancestor—the land-dwelling, wolf-sized Pakicetus—could only stay submerged for about 90 seconds. However, the larger, six-ton Basilosaurus, which appeared roughly 15 million years later, could remain underwater for around 17 minutes. Many modern whales can stay submerged for over an hour. [Nature]
More from The Week...
3D Printed Batteries the Size of a Grain of Sand
*
Do Synthetic Fossil Fuels Have a Place in the Future?
*
Everything You Need to Know About Investing in Gold
