Humpback whales commonly grow to a length of close to 50 feet, and by the time they are adults, they weigh roughly one ton per foot of body length. Yet with as few as three beats of its tail an adult humpback is able to launch itself almost completely out of the water in a behavior known as breaching. It is difficult to comprehend how powerful and well adapted for life in the oceans humpbacks must be to accomplish this feat. Yet, if you ask anyone who has spent time observing humpbacks, they will almost certainly tell you that the real power of these magnificent creatures is their ability to capture the hearts and minds of so many people. This phenomenon is experienced by ocean goers that are lucky enough to enjoy a sighting, something that happens relatively often in California, Hawaii, Mexico’s Sea of Cortez and Revillagigedo archipelago, and numerous other locales.
Their Place in the World of Whales
Worldwide, there are approximately 80 species of whales. With regard to their classification, these marine mammals are described in the order Cetacea, a group that is divided into two suborders; Odontoceti, the toothed whales, and Mysticeti, the baleen, or filter feeding, whales.
The 67 species of toothed whales, a group that includes species such as the sperm whale and orca, prey chiefly upon fishes and other mammals. The 13 species of baleen whales, a group that includes the humpback, utilize hundreds of strong, elastic, horny plates made of keratin that hang from their upper jaw to strain seawater for tiny planktonic organisms, some small fishes, and crustaceans. The plates are also known as baleen.
Like other baleen whales, humpbacks only have teeth during their embryonic stage. As adults, they are equipped with as many as 400 baleen plates.
Species Overview
Mature humpbacks typically range in length from 35 to 48 feet, with the average full-grown female being slightly longer than the average male. The most easily seen distinguishing feature of both sexes is their long pectoral flippers. These fins grow to 15 feet in length, making them close to one-third the length of the bodies of the adults.
The significance of their long pectoral fins as an identifying characteristic is reflected in their taxonomic name, Megaptera novaeangliae. The genus name is derived from the Greek words mega meaning giant and ptera meaning wing, an obvious reference to their long pectoral flippers. The species name, novaeangliae, is a Latin derivation from French words meaning New England. The humpback population in the waters off New England was well known to Europeans by the mid-1750s.
The body of a humpback whale is generally stocky with a smallish, somewhat knobby dorsal fin that varies in shape. While calves exhibit noticeably lighter hues, the bodies of adults are typically dark gray to bluish black. However, individual animals have widely varying amounts of white on their pectoral flippers and underbelly. The individual variations are so distinctive that markings on the underside of the tail flukes can be used to identify individuals in the same way that fingerprints can be used to identify humans.
Their broad head looks somewhat rounded when viewed from above, but unless the throat pleats have been expanded, the head of these behemoths have a surprisingly slim profile. Wart-like bumps called tubercles that are enlarged hair follicles are present on both the upper and lower jaw.
Like other rorqual whales, humpbacks are equipped with 25 to 50 expandable pleats on the underside of the throat. The pleats allow the whales to greatly enlarge their throat in accordion-like fashion when feeding. Mature males also expand their the throat to make themselves appear bigger when they compete with each other, and when trying to woo females. Females likely look with favor upon larger males, as size can be an indication of fitness, and therefore, reflects the worthiness of a male as a potential mate.
Humpbacks, like all mammals, breathe air. The air is drawn in and expelled through openings known as blowholes located on the top of the head. Like all filter feeding whales, humpbacks posses a pair of blowholes. All toothed whales have a single blowhole.
The reproductive organs of both sexes are internal. Females can be distinguished from males by noting the presence of a “bump”” called the “hemispherical lobe” located on the underside of the body between the umbilicus, the area on the body where the umbilical cord was attached, and the anus. The female’s mammary slits are found just forward of the hemispherical lobe.
Distribution
Humpbacks inhabit all of the world’s major oceans, although they are not known in the eastern Mediterranean or the Baltic Sea. Worldwide there are four distinct major populations. They are the North Atlantic, North Pacific, Southern Oceans, and Indian Ocean populations.
DNA studies have revealed that these populations do not interbreed, nor have they for thousands of years. However, the separated populations share many common traits and behaviors including similar migration patterns, with the exception of the Indian Ocean population. Indian Ocean humpbacks are unable to migrate due to the large landmass that forms the northern coastline of the Indian Ocean.