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The tail of a sperm whale (Physeter macrocephalus), raised in a deep dive -- beyond it is another whale at the surface. Great whalewatching on a trip with Sea of Whales Adventures!
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This is a video composed of 87 still photos, many taken in continuous mode at about 7 per second. Not a pretty video, but an interesting experiment. I used iMovie.
Humpback whales are rorquals (Balaenopteridae, a family that includes the blue, fin, Bryde's, sei, and minke whales). The rorquals are believed to have diverged from the other families of the suborder Mysticeti as long ago as the middle Miocene. The sole member of its genus, the humpback was first identified as baleine de la Nouvelle Angleterre off the coast of New England by Mathurin Jacques Brisson in his Regnum Animale of 1756. The common name is derived from the curving of their backs when diving. The generic name Megaptera comes from the Greek mega-/μεγα- ("giant") and ptera/πτερα ("wing") and refers to their large front flippers.
Genetic research in mid-2014 by the British Antarctic Survey confirmed that the separate populations in the North Atlantic, North Pacific, and Southern Oceans are more distinct than previously thought. Some biologists believe that these should be regarded as separate, independently evolving subspecies.
Humpbacks have a stocky body, obvious hump, and black dorsal colouring. The head and lower jaw are covered in tubercles, knobby hair follicles characteristic of the species. Humpbacks have 270-400 dark baleen plates on each side of their mouths. The plates measure from 46 centimetres in the front to almost a metre in the back. About 14-22 wide ventral grooves run from the lower jaw to the umbilicus. The female has a hemispherical lobe about 15 centimetres in diameter in her genital region. Fully grown males average 13-14 metres and females are slightly larger at 15-16 metres; one large recorded specimen was 19 metres long and had pectoral fins measuring 6 metres each. Body mass is typically around 25-30 metric tons, with large specimens weighing over 40 metric tons.
The long black and white tail fin can be up to a third of body length. The varying patterns on the tail flukes distinguish individual animals. During a study using data from 1973 to 1998 on whales in the North Atlantic, a photographic catalogue of all known North Atlantic whales was developed; it's maintained by the College of the Atlantic. Several hypotheses attempt to explain the humpback's pectoral fins, proportionally the longest fins of any cetacean, such as higher maneuverability and increased surface area for temperature control when migrating between warm and cold climates.
Whales produce a three-metre-long, heart-shaped blow through the blowholes. They don't generally sleep at the surface but must continue to breathe: it's possible that only half of their brain sleeps at one time, allowing the other half to manage the surface/blow/dive process.
The lifespan of rorquals ranges from 45 to 100 years. Females reach sexual maturity at age five, achieving full adult size a little later. Males reach sexual maturity around seven years of age. Courtship rituals take place during the winter months, following migration toward the equator from summer feeding grounds closer to the poles. Competition is usually fierce. Unrelated males, or "escorts," frequently trail single cows and cow-calf pairs. Males gather into "competition groups" around a female and fight for the right to mate with her. Groups shrink and grow as unsuccessful males retreat and others arrive. Behaviors include breaching, spy-hopping, lob-tailing, tail-slapping, pectoral fin-slapping, peduncle throws, charging, and parrying.
Both male and female humpback whales vocalize, but only males produce the long, loud, complex song for which the species is famous. Each song consists of several sounds in a low register, varying in amplitude and frequency and typically lasting from 10 to 20 minutes. Individuals may sing continuously for more than 24 hours. Cetaceans have no vocal cords, instead forcing air through their massive nasal cavities (blowholes).
Whales within a large area sing a single song: all North Atlantic humpbacks sing the same song, while those of the North Pacific sing a different song. Each population's song changes slowly over a period of years without repeating. Many of the whales observed to approach a singer are other males, often resulting in conflict: singing may, therefore, be a challenge to other males as well as a way to impress females. Some scientists have hypothesized the song may serve an echolocative function. During the feeding season, humpbacks make unrelated vocalizations to herd fish into their bubble nets and they use other sounds to communicate, such as grunts, groans, "thwops," snorts, and barks.
Females typically breed every two or three years. The gestation period is 11.5 months. The peak months for birth are January, February (northern hemisphere), July, and August (southern hemisphere). Females wait for one to two years before breeding again. Recent research on mitochondrial DNA reveals that groups living in proximity to each other may represent distinct breeding pools.
A newborn calf is roughly the length of its mother's head. At birth, calves measure six metres and two tons. They nurse for about six months, then mix nursing and independent feeding for around six months more. Humpback milk is pink and 50% fat.
Humpbacks have a loosely knit social structure: individuals usually live alone or in small, transient groups that disband after a few hours. Groups may stay together longer in summer to forage and feed cooperatively. Longer-term relationships of months or even years between pairs or small groups have occasionally been observed, and some females might create lifelong bonds through cooperative feeding.
Humpbacks inhabit all major oceans, in a wide band running from the Antarctic ice edge to 77° N latitude. The four distinct tribes are the North Pacific, Atlantic, Southern Ocean, and Indian Ocean populations. Whales were once uncommon in the eastern Mediterranean or the Baltic Sea but have increased their presence in both waters as global populations have recovered. They have also returned to Scotland, Skagerrak, and Kattegat, as well as Scandinavian fjords such as Kvænangen, where they had not been observed for decades. Since November 2015, Hachijo-jima has been recognized as the northernmost breeding ground in the world.
Humpbacks typically migrate up to 25,000 kilometres each year. A 2007 study identified seven individuals wintering off the Pacific coast of Costa Rica as having traveled from the Antarctic—around 8,300 kilometres. Identified by their unique tail patterns, these animals made the longest mammalian migration ever documented.
The humpback's range overlaps with other whale and dolphin species. Humpbacks are friendly and interact with other cetaceans such as bottlenose dolphins and right whales. These behaviors have been recorded in all oceans, and humpback whales regularly appear in mixed groups with other species, such as the blue, fin, minke, gray, and sperm whales. Humpback and southern right whales demonstrating what were interpreted to be mating behaviors have been observed off the Mozambique and Brazilian coasts. A male humpback whale was seen singing to a fin whale at Rarotonga in 2014, and another individual was observed playing with a bottlenose dolphin in Hawaiian waters. Incidents of humpback whales protecting other species of animals such as seals and other whales from killer whales have also been documented.
Humpbacks feed primarily in summer and live off fat reserves during winter, when they feed only rarely and opportunistically. The humpback is an energetic hunter, taking krill and small schooling fish such as herring, salmon, capelin, and American sand lance, as well as Atlantic mackerel, pollock, and haddock in the North Atlantic. Pleated grooves in the whale's mouth allow water to easily drain out, filtering out the prey. The humpback has the most diverse hunting repertoire of all baleen whales, sometimes stunning prey by hitting the water with pectoral fins or flukes. Its most inventive technique is known as bubble net feeding, in which a group of up to a dozen whales swims in a shrinking circle below a school of prey and traps it in a cylinder of bubbles. The ring can start out about 30 metres in diameter. Some whales blow the bubbles, some dive deeper to drive fish toward the surface, and others herd prey into the trap by vocalizing. The whales then all suddenly swim up, swallowing thousands of fish.
The technique of lobtail feeding, observed in the North Atlantic, involves slapping the surface of the ocean with the tail up to four times before creating the bubble net. Based on network-based diffusion analysis, researchers believe that these whales learned the behavior from other whales in the group over a period of 27 years in response to a change in the primary form of prey.
Visible scars indicate that killer whales can prey upon juvenile humpbacks. Mothers and (possibly related) adults escort neonates to deter such predation. It's believed that orcas turned to other prey when humpbacks suffered near-extinction during the whaling era but are now resuming their former practice.
Humpback whales were hunted by humans on a commercial level as early as the 18th century. By the 19th century, many nations (the United States in particular) were hunting the animal heavily in the Atlantic and to a lesser extent in the Indian and Pacific oceans. The explosive harpoon introduced in the late 19th century, along with the extension of hunting into the Antarctic ocean from 1904, drastically reduced whale populations. During the 20th century, over 200,000 humpbacks were taken, reducing the global population by over 90%. North Atlantic populations dropped to as low as 700 individuals.
In 1946, the International Whaling Commission (IWC) was founded: they imposed hunting regulations and seasons. To prevent extinction, IWC banned commercial humpback whaling in 1966, by which time the global population had been reduced to around 5,000 animals (around 90% having been exterminated). The Soviet Union deliberately under-recorded its catches; the Soviets reported catching 2,820 whales between 1947 and 1972, but the true number was over 48,000.
As of 2004, hunting was restricted to a few animals each year off the Caribbean island of Bequia in the nation of St. Vincent and the Grenadines. The take is not believed to threaten the local population. Japan's announcement that it planned to kill 50 humpbacks in the 2007/08 season under its JARPA II "research" program sparked global protests and a visit to Tokyo by the IWC chair, and the Japanese whaling fleet agreed to take no humpback whales during the two years it would take to reach a formal agreement. In 2010, the IWC authorized Greenland's native population to hunt a few humpback whales for the following three years.
In Japan, humpback, minkes, sperm, and many other smaller Odontoceti, including critically endangered species such as North Pacific right, western gray, and northern fin whales, have been targets of illegal captures. Humpback meat can be found on the markets. Harpoons are used to hunt dolphins or intentionally drive whales into nets, reporting them as cases of entanglement. Unknown numbers of humpbacks have been illegally hunted in the Exclusive Economic Zones of anti-whaling nations such as off Mexico and South Africa.
Because they're easily approachable, curious, identifiable as individuals, and display many interesting behaviors, they have become the mainstay of whale tourism around the world. Analyses of whale songs in the 1960s led to worldwide media interest and convinced the public that whales were highly intelligent, aiding the anti-whaling advocates. Humpbacks are popular with whale-watchers because of their distinctive surface behaviors: they frequently breach, throwing two-thirds or more of their bodies out of the water and splashing down on their backs. Some humpbacks, referred to as "friendlies," often stay under or near whale-watching boats for many minutes.
While whaling no longer threatens the species, individuals are vulnerable to collisions with ships, entanglement in fishing gear, and noise pollution. Like other cetaceans, humpbacks can be injured by excessive noise. In the 19th century, two humpback whales were found dead near sites of repeated oceanic sub-bottom blasting, with traumatic injuries and fractures in the ears.
The species was listed as vulnerable in 1996 and endangered as recently as 1988. In August 2008, the IUCN changed humpback's status from "vulnerable" to "least concern," although two subpopulations remain endangered. Most monitored stocks have rebounded since the end of commercial whaling and now reach around 80,000 worldwide. Though the North Atlantic stocks are believed to be approaching pre-hunting level, the species is still considered endangered in some countries, including the United States.