By Dr. Becker
Young humpback whales frequently jump out of the water and slap the surface on the way back down. The behavior, known as breaching, displays the animals’ physical prowess but its purpose remains a mystery.
It’s been suggested that whales may breach to remove parasites from their body, communicate with other whales, to get a glimpse above the surface or simply for fun. One peculiarity, however, is that very young humpback whales often engage in extended breaching sessions, a behavior that is not observed among adult whales.
Researchers from California State University, Channel Islands, decided to investigate and revealed the extensive breaching may actually be a form of exercise.1
Young Whales May Breach for Exercise
Female whales only have a limited amount of energy to devote to feeding their growing calves, which raised questions of why young whales would engage in frequent breaching (which requires considerable energy) for “no good reason.”
Researchers took muscle tissue samples from 18 stranded baleen whales and analyzed stores of myoglobin, a protein-containing compound that stores oxygen in muscle cells (similar to hemoglobin in humans).
Whales depend on elevated levels of myoglobin in their muscles to make extended dives. It allows them to store ample oxygen in their muscles to be used during deep dives. Young calves, however, have only about 20 percent of the myoglobin stores of adult whales, the researchers found.
Myoglobin levels are known to increase as whales mature, but it turns out, these levels are also positively influenced by exercise. Study co-author Rachel Cartwright, Ph.D. told Seeker:2
“This study provides a functional explanation for these high activity levels; this intense exercise drives development of oxygen stores in the muscle tissue, allowing young whales to build their breath-holding capacity and make sustained, extended dives.”
Young Whales May Be Especially Vulnerable to Changing Marine Environments
Whales’ ability to hold their breath for extended periods gives them a distinct advantage when it comes to foraging for krill and small fish. An adult humpback whale can dive to depths of 500 to 700 feet and stay underwater for up to 30 minutes (though most dives last only about 15).3
Young whales have not yet developed the ability for such extended dives, and therefore must depend on food closer to the surface (after being weaned from their mother’s milk). This means young whales may be particularly vulnerable to changes in their marine environment. According to the study:
“Based on recent simulations of mysticete [baleen whale] dive capacities these factors may prove to be very pertinent in discussions of breath-hold capacity and the associated foraging tactics used by both young and mature mysticetes.
… For now, as marine resources enter a period of unprecedented change, these results bring focus to the physiological constraints on diving and foraging in young and maturing mysticetes, allowing informed insight into their resilience to the impending challenges facing marine fauna.”
Do Other Animals Exercise to Get Fit?
It’s unknown if animals other than humans engage in physical activity for the sole purpose of getting and staying fit. Doing so could promote agility, speed and strength that could offer a survival advantage, but they would have to offset the intensive energy demands of the exercise to be useful.
Lewis Halsey, Ph.D. of the University of Roehampton suggested that animals may prioritize fitness depending on their environment.4
"Barnacle geese appear to get fit for certain predictable, planned events such as migration and yet miraculously seem able to do so with little or no voluntary exercise. So their bodies seem to trigger increased fitness from within — they get fit automatically when they need to.”
Whether or not other animals put in effort to maintain their speed and other elements of fitness remains to be seen. Halsey continued:6
"If animals are undertaking activities solely or partly to keep fit, this opens up a significant new facet to our understanding and interpretation of animal behavior. No one has previously observed animal behaviors and thought 'this behavior could be associated with keeping fit.'”
Humpback Whales Are Incredible Creatures
The fact that young humpback whales may breach frequently to build up their myoglobin stores is not surprising when you learn some of their other amazing feats. Humpback whales are a type of baleen whale (along with gray whales and blue whales), which are known as the “great whales.”
Humpback whales have long been given the title of longest-migrating mammal, as they travel up to 10,190 miles round trip from the cold waters near Antarctica to the warm, tropical waters of the Pacific. However, this distinction was recently handed over to the gray whale, which was found to travel nearly 14,000 miles round trip.
Another distinctive feature is their ability to sing complex “songs” that may be heard up to 20 miles away. The songs are used to communicate, likely as part of mating behavior, but even the way they’re produced is fascinating. According to the Sea Shepherd Conservation Society:7
“Researchers still are not sure exactly how humpbacks produce their sounds. They don't have vocal cords, so they probably sing by circulating air through the tubes and chambers of their respiratory system — but no air escapes during the concerts and their mouths don't move.”
Humpbacks can not only learn songs from one another, but they also learn and imitate hunting behaviors of those in their social circle. They’ve also been caught on camera showing joy and appreciation after being rescued from fishing nets. And in case you were wondering, humpback whales don’t actually have “humpbacks.” They were named for the shape of their back (dorsal) fin as well as the way they arch their back into a “hump” when preparing to dive.8