Humpback Whale

"We sent whalesong into interstellar space because the creatures that sing these songs are superlative beings that fill us with awe, terror, and affection. We have hunted them for thousands of years and scratched them into our mythologies and iconography. Their bones frame the archways of medieval castles. They’re so compelling that we imagine aliens might find them interesting — or perhaps understand their otherworldly, ethereal song."
~ Nick Pyenson, Spying on Whales: The Past, Present, and Future of Earth's Most Awesome Creatures

Humpback whales are members of the Balaenopteridae family, the largest group of baleen whales which diverged from other baleen whales in the late Miocene, some 6-10 million years ago. Also known as rorquals (from the Norwegian word røyrkval), members of this family are slender and streamlined with a dorsal fin situated about two-thirds of the way back, and most have narrow, elongated flippers. A few other rorquals are the blue whale, fin whale, sei whale, and minke whale. Most members of family Balaenopteridae have a series of longitudinal folds of skin running from below the mouth back to the navel. These folds allow the mouth to expand considerably when gulping huge mouthfuls of water (or sediment, in the case of the gray whale). The humpback whale gets its common name from the distinctive hump on its back. It’s scientific name, Megaptera novaeangliae, refers to its wing-like pectoral fins and the location where European whalers first encountered them, New England.

Adult female humpbacks can reach over 55 feet in length and weigh up to 40 metric tons. Males are typically a bit smaller. Calves are born around 15 feet long and weigh about 1,500 pounds. Their backs are primarily black and undersides have various amounts of black and white. Whales in the Southern Hemisphere tend to have more white markings, particularly on their flanks and bellies, than those in the Northern Hemisphere. Flippers can also vary from all white, to black on top with white on bottom and are each around one-third of the body length. The short dorsal fin varies in size from nearly non-existent to somewhat long and curved. Tail flukes can be up to 18 feet wide. They are serrated along the trailing edge, and pointed at the tips. The fluke’s pigmentation patterns, size, and/or prominent scars are unique to each animal. They are distinctive enough to identify individuals. The mouth is lined with baleen plates, which can number up to 800. Forward of the blowhole on both the upper and lower jaw, as well as along the leading edge of the flippers, are rounded bumps, called tubercles – the outermost components of a sensory system we don’t know much about. They range in diameter from 2-4 inches and are just under 3 inches tall. At the center of each tubercle is a funnel-shaped pit, and usually in the center of this pit is a single hair (some tubercles may have no hair, and some up to two). The tubercles are rich in nerves, each having an estimated 150-350 nerve endings, suggesting a rich sensory perception of the whale’s surroundings.

Humpbacks live in all oceans around the world. They hang out in disorganized pods and can travel the globe within their lifetime. Humpbacks make some of the longest migrations of any whale, traveling thousands of miles each year. In the North Pacific, some humpback whales make a 3,000-mile trip in as few as twenty-eight days. They migrate between colder, more-productive feeding grounds and warm, shallow waters for calving. The prey of humpback whales are microscopic compared to their own gigantic bodies. They gulp huge mouthfuls of seawater and plankton, tiny crustaceans like krill and other small schooling fish. Using their baleen plates, they then strain out the water. An adult humpback whale can consume nearly 3000 pounds of plankton each day. They use several techniques to help them herd and disorient prey, including bubbles, sounds, the seafloor, and even their pectoral fins. One specific feeding method, called bubble net feeding, involves using curtains of air bubbles to condense prey. A group of whales swim in a shrinking circle while blowing air from their blowholes, capturing the prey above them in a cylinder of bubbles. Once the fish are corralled, they are pushed toward the surface and devoured in several massively efficient gulps. Different groups of humpback whales use other bubble structures in similar ways; there appears to be some regional specialization in bubble-feeding behaviors among populations. In the southern hemisphere, humpbacks have been recorded foraging in large compact gatherings numbering up to 200 individuals. They are the only baleen whales known to utilize bubble-net feeding. They feed only during certain months of the year prior to calving season. Adult humpbacks are so large that only a few other creatures, including orcas and the great white shark, are known to attempt to feed on them. Humpbacks often wear scars of these battles.

Male humpbacks produce complex songs during the winter breeding season, ranging in frequency from 4-100 hertz (Hz), with harmonics reaching up to 24 kHz or more. (The widely accepted range of human hearing is 20 Hz to 20,000 Hz (20 kHz), though many adults top out at 14-15 kHz. 20-80 Hz is our true low end. In fact, the bottom half of that range (20-40 Hz) is felt more than heard. The upper half (40-80 Hz) is where the lowest note of the four-string bass comes into play. 80-160 Hz is commonly considered the bass range. The guitar enters the spectrum here. 10 kHz is very shrill, and there’s plenty of YouTube videos for that experience). Humpback vocals can travel several miles. Males typically sing for 4-33 minutes, depending on the region, though some have been recorded vocalizing for as long as seven hours. The whale repeats itself while hanging motionless in the water, head down. The function of these songs has been debated, but they may have multiple purposes, including attracting females, asserting dominance, and locating other whales. Songs can evolve over time as a result of contact between whales. One whale hears another, and incorporates part of that song into his own, which he then spreads to the next whale. Apparently, all males sing the same basic song, with minor changes. Humpbacks do make an assortment of other vocalizations besides singing – including snorts, grumbles, “thwops,” cries, shrieks, and barks – to communicate between individuals and groups. They are very active at the surface, performing behaviors such as breaching, tail slapping, and flipper slapping. These may be forms of play and communication and/or for removing parasites, or even possibly for regulating their body temperature. The species is a slower swimmer than other rorquals, cruising at 5-10 mph. Though when threatened, they might speed up to 17 mph.

Humpback whales can live 100 years. They reach sexual maturity somewhere between 4 and 10 years, around 41 feet in length. They are a promiscuous species, with both sexes having multiple partners. Males will frequently trail both lone females and cow–calf pairs. These are known as escorts, and the male that is closest to the female is known as the principal escort. He’s in charge of fighting off other suitors. The other trailing males, called secondary escorts, follow further behind and get to just watch the conflicts like a reality TV show. Calves are born after an 11- to 12-month gestation period and measure about 13 to 16 feet in length. They suckle for up to a year but can eat adult food in six months. Females produce a single calf every 2 to 3 years on average.

Before a final moratorium imposed on commercial whaling by the International Whaling Commission in 1985, all populations of humpback whales were greatly reduced, most by more than 95 percent. Humpbacks were hunted as early as the late 16th century. They were often the first species to be harvested in an area due to their distribution near coastlines during calving season. The United States listed all humpback whales as endangered under the Endangered Species Conservation Act in 1970. Before then, North Atlantic populations dropped to as low as 700 individuals. NOAA Fisheries worked worldwide to identify and apply protections for humpback whales – with happy results. Megaptera novaeangliae was most recently assessed by the IUCN Red List of Threatened Species in 2018, and as a whole, was classified as Least Concern, though some populations are still considered depleted, and as such remain protected under the Marine Mammal Protection Act and the Endangered Species Act.

Some threats still exist. The impacts of climate change on whales are as yet unknown, but it is considered one of the largest threats facing high latitude regions where many humpback whales forage. The timing and distribution of sea ice coverage is changing dramatically. Any resulting changes in prey distribution could lead to changes in foraging behavior, nutritional stress, and diminished reproduction for humpback whales. Additionally, changing water temperature and currents could impact the timing of environmental cues important for navigation and migration. Other threats include vessel strikes, entanglement by fishing gear, human-caused noise and traffic disturbance, and coastal habitat destruction. Like other cetaceans, humpbacks can be injured by excessive noise. In the 19th century, two humpback whales were found dead near a site of repeated oceanic sub-bottom blasting, with injuries and fractures in their ears.

Because humpback whales are often found close to shore and are often active, jumping out of the water and slapping the surface with their pectoral fins or tails, they tend to be popular whale watching attractions. There are several areas in the United States where they are the central attraction for the whale watching industry. Humpback whales are uncommon visitors to the Gulf of Mexico, with only 19 sightings between 1966 and 2015 – so consider yourself doubly lucky if you catch a glimpse.

Where I learned about humpback whales, and you can too!

World Register of Marine Species
www.marinespecies.org/aphia.php?p=taxdetails&id=137092#notes

NOAA Fisheries
www.fisheries.noaa.gov/species/humpback-whale

Whale & Dolphin Conservation
us.whales.org/whales-dolphins/species-guide/humpback-whale/

American Oceans
www.americanoceans.org/species/humpback-whale/

IUCN Red List
www.iucnredlist.org/species/13006/50362794

National Library of Medicine
www.ncbi.nlm.nih.gov/pmc/articles/PMC5884691/

ResearchGate
www.researchgate.net/publication/269519644_Short_Note_Tubercles_What_Sense_Is_There
www.researchgate.net/publication/293325880_Humpback_whale_Megaptera_novaeangliae_occurrence_in_the_Gulf_of_Mexico

Sonic Bids
blog.sonicbids.com/understanding-frequencies-how-to-describe-what-youre-hearing-to-your-sound-tech

Wikipedia
en.wikipedia.org/wiki/Humpback_whale
en.wikipedia.org/wiki/Rorqual