Known for their mystical songs, global travel and impressive gymnastics, humpback whales (Megaptera novaeangliae) are one of the ocean's most captivating and complex giants. While they aren't as big as the blue whale, the largest animal on the planet, humpback whales are still quite the whoppers, growing up to 60 feet (18.3 meters) long and weighing up to 40 tons (36 metric tons). That's about the length of one city bus but the weight of two.
The hump that forms under their small dorsal fin when they breach — the act of throwing part or all of their bodies out of the water — gives them their recognizable name. They have a uniquely huge tail and pectoral fins, their backside is black and their underbelly is a varying mix of both black and white. What appear from a distance to be decorative lines on their underside are actually ventral pleats. These pleats fold open and allow the whale's throat cavity to expand so they can scoop up copious amounts of water (and thus their prey) when they feed.
Humpback whales are one of 14 species of baleen whales, a type of whale that has baleen plates — long, bristly hairs made of keratin attached to their upper jaw — instead of teeth. Despite their massive size, humpback whales like to chow down on much smaller sea creatures — plankton, krill, anchovies, cod, sand lance and capelin. They gulp in enough water to fill a swimming pool, and then when they expel it, the baleen plates filter out those tiny, tasty creatures.
If you're imagining a diver getting scooped up in all that water, never fear. These massive whales aren't built to swallow large animals. While their esophagus stretches a little when they swallow a meal, their throat (and those of most whale species) isn't any wider than a human fist. And if you end up in their mouth by mistake, you'd promptly be spit out.
Such was the case for dive tour operator Rainer Schimpf when he accidentally found himself inside the mouth of another baleen whale, the bryde whale. He shares in this video that the experience was a unique and special moment, but it definitely wasn't a whale of a time:
Humpback whales can be found in all oceans around the globe, in part due to having one of the longest migration patterns of all mammals. Humpback populations spend part of the year feeding and fattening up in colder waters and then head south to tropical or subtropical waters to focus on mating. Females generally produce a single calf every two to three years on average, which might not seem like much, but they'll stick around for approximately 80 to 90 years.
They're the Acrobats of the Ocean
Humpback whales tend to live closer to shore and their propensity to slap the water and breach the surface makes them a frequent and awe-inspiring sight for whale watchers. Ed Lyman, a Natural Resource Management Specialist at the Hawaiian Islands Humpback Whale National Marine Sanctuary, shared in an email interview that scientists believe these acrobatics likely serve more than one purpose.
"First, it may be a grooming or cleaning mechanism. You throw all or most of 40 tons (in the case of a typical adult humpback whale) of your body out of the water and come crashing back down, you are very likely to remove loose skin, parasites and in general any bio-fouling. Doing so reduces drag and helps maintain the animal's hydrodynamic form (it reduces your energy budget)," he explains.
Other possibilities include the sound of the splash as a means of communication and the movement/sounds as breeding signals. Lyman says "... throwing one's body out of the water could be a display behavior, representing aggression or competitiveness.... [W]e sometimes see the whales exhibit breaching behavior or lesser extents of throwing their bodies out of the water as part of their breeding behavior displays."
But what's life without a little play. "It may just be fun. When we see calves breaching in sanctuary waters we tend to lean toward this interpretation. Though this applies to adults as well," Lyman says.
Males Have Some Serious Singing Skills
Humpbacks are master communicators — the males compose grunts and whines into complex songs that travel great distances underwater. Researchers are still debating the exact purpose of the music, but Marc Lammers, Ph.D., a research ecologist with the Hawaiian Islands Humpback Whale National Marine Sanctuary, shares in an email interview: "Generally speaking, male humpback whale song is considered to be a mating display, as it is correlated to the breeding season."
But he says the biggest question is who exactly the males are serenading. While it's possible that females choose their mates based on their song, there is little evidence so far. "There is more behavioral evidence to suggest that other males pay close attention to the singing of their competitors. As a result, several researchers (myself included) believe that song may help to mediate male-male interactions by potentially communicating the competitive fitness of a singer to potential competitors," Lammers says.
It's definitely not about who has the best lyrics. Lammers explains that males within each population sing the same song, with a little room for improvisation, of course. But just as we humans have different voice characteristics, so do the whales. "It's that individual variability that may carry important information about a male's fitness, and therefore its ability to compete for a female, that other males (and possibly females) may be listening for," he says.
The Humpback Whale Population Is Making a Comeback
Due to years of commercial whaling, the entire humpback population was listed as endangered in 1970. But things started looking up in 1985 when the International Whaling Commission's final whaling moratorium on commercial harvest took effect. Today they still sometimes get caught in fishing gear or collide with boats, but their population is thankfully increasing — only four out of the 14 distinct populations are still listed as endangered. With continued conservation, the gentle giants will continue to sing, splash about and amaze us all.