The Humpback Whale (Megaptera novaeangliae) is a marine mammal that is part of the Balaenopteridae family. This cetacean is distinguished by its long pectoral fins, which can measure up to 4.6 meters. In addition, in its jaw and head it has dermal tubercles. These are sensory hair follicles, typical of this species.
It has a robust body, with the dorsal part black, while the ventral is mottled in black and white. Its tail is flattened, which, when plunging into the depths, rises above the ocean surface.
The Megaptera novaeangliae it has ventral folds, which go from the jaw to the middle part of the belly. These allow the throat to expand during feeding.
The humpback whale is distributed in all oceans, inhabiting from the pole to the tropics. It is located in deep waters, although at times it could approach the coasts. Their diet is made up of krill and small fish. To capture them, he uses various techniques, among which are the cloud of bubbles and vertical swimming..
Males are characterized by vocalizing songs that are frequently repeated in the breeding areas, which could be associated with courtship and mating..
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The humpback whale has a short, robust, rounded body. It has between 12 and 36 ventral folds, located from the chin to the navel. The space between each fold is greater than in other balenoptera.
In the genital area, the female has a hemispherical lobe that measures about 15 centimeters. This allows to visually distinguish the female from the male. In relation to the penis, it is usually hidden within the genital cleft.
Unlike other baleen whales, Megaptera novaeangliae It has narrow and very long pectoral fins, with a length of 4.6 meters. This particular feature offers greater maneuverability in swimming and expands the body surface area, thus contributing to internal temperature control..
As for the dorsal fin, it could measure up to 31 centimeters in height. The tail is serrated on the trailing edge and is approximately 5.5 meters wide. At the top it is white, while ventrally it is black.
Dermal tubercles are on the jaw, chin, and rostrum. Each of these has a sensory hair, which is between 1 and 3 centimeters long. Likewise, these structures are found on the leading edge of each pectoral fin, and may be related to the detection of prey.
These measure from 46 centimeters, in the area of the forehead, to 91 centimeters, those located towards the posterior region. These structures are superimposed and are formed of keratin, which at the end of the beard becomes fine fringes, which hang down from the jaw..
The humpback whale's epidermis is, on average, 10-20 times thicker than that of land animals. In addition, it lacks sweat glands..
This species has a layer of fat that could exceed, in some parts of the body, 50 centimeters. Said coating serves as an insulating element against low water temperatures. In addition, it is an energy reserve and contributes to the buoyancy of the animal.
The humpback whale exhibits sexual dimorphism, with the females being larger than the males. This difference in body constitution could be the product of evolution, due to the immense energy demand required by the female during pregnancy and lactation..
Thus, it can have a length of 15 to 16 meters, while the male measures between 13 and 14 meters. Regarding body mass, it is in the range of 25 to 30 metric tons. However, species of up to more than 40 metric tons have been recorded.
As in the vast majority of Antarctic balenoptera, humpback whales that live in the northern hemisphere tend to be smaller than those in the south..
At the end of this video you can see the size of a humpback whale specimen:
The dorsal region of the body is black, while the lower area is mottled in black and white. The fins can be from white to black. The color pattern of the dorsal fins is individual, so it can be used as a reference to differentiate a species from the rest of the group..
The coloration may vary depending on the area you inhabit. Thus, those located in the South, with the exception of South Africa and South Georgia, tend to be whiter than those in the North..
Because light and sound travel differently in water compared to air, the humpback whale has developed adaptations in some of the sense organs.
The humpback whale's eye structure makes it sensitive to light, which is a huge advantage, considering the dark conditions in its natural habitat. Likewise, the lack of cones could be an indication that this species lacks color vision..
The Megaptera novaeangliae It does not have external ears, however, it has an internal system of bones and air sinuses that are responsible for the transmission of sound waves.
Animal Kingdom.
Subkingdom Bilateria.
Chordate phylum.
Vertebrate Subphilum.
Tetrapoda superclass.
Mammal class.
Subclass Theria.
Infraclass Eutheria.
Order Cetacea.
Suborder Mysticeti.
Balaenopteridae family.
Genus Megaptera.
Species Megaptera novaeangliae.
Experts indicate that this philopatry responds to eating patterns, where adults return to the feeding areas they used with their mother.
In the northern hemisphere it is found in the North Atlantic, Newfoundland, in the Gulf of Maine and in that of San Lorenzo Also, it lives in West Greenland, north of Norway and in Iceland. The main place of reproduction is in the West Indies and in the Caribbean, from Cuba to Venezuela, with a small grouping in the islands of Cape Verde.
During the summer, this species ranges from the Gulf of Maine to Norway and the British Isles. To the north, it inhabits the Greenland Sea, the Barents Sea and the Davis Strait.
On the other hand, it is difficult to spot it in the south and center of the North Sea and in the Baltic Sea. It was previously rare to find this whale in the Mediterranean Sea, but that is changing. Since 1990 the population in that area has increased, but still these are not considered stable.
Specialists have noted the existence of an exchange of Megaptera novaeangliae between areas of the western and eastern Atlantic, so in the winter they could remain in more northern and colder waters.
In this ocean, the summer range covers from the Gulf of Alaska to southern California, northeastern Japan, the Bering Sea, the Kamchatka chain, and the Aleutian..
Regarding the wintering areas, these are: Bonin Island (Asia), the Ryukyu Islands (Okinawa), the northern Philippines, the Mariana Islands, Hawaii, the Gulf of California, Colombia, Panama and Costa Rica. The movements between these areas are scarce, so the populations remain genetically differentiated.
The Central American winter terrain surpasses the range of those that inhabit the south. However, this is temporary, as southern humpback whales occupy the space in the southern winter..
The humpback whales of this hemisphere were divided into several populations, between 5 or 6. Each of these corresponds to a group that migrates to the southern coastal waters. During the summer, this species abounds in Antarctica, without entering the ice zone.
On the other hand, in the winter, they are added near the Atlantic, Pacific and Indian coasts. As for the wintering areas, they can be located around a group of islands. Also, they may be dispersed, as is the case along the western coast of South Africa and the southern coast of West Africa..
Megaptera novaeangliae migrates to the coastal area in eastern Australia. Likewise, it usually lives in the winter on the Great Barrier Reef or on the reefs of the Coral Sea. In Oceania, it is found in Fiji, New Caledonia, Tonga, the Cook Islands, and in French Polynesia.
There is a resident population in the Arabian Sea, in which it is found throughout the year. That range includes Iran, Yemen, Pakistan, Oman, Sri Lanka, and India. Currently, this species shows regular in the Persian Gulf, where it was previously considered a wandering population..
The humpback whale migrates between the southern and northern latitudes, in accordance with the seasons. This mobilization is associated with reproduction and feeding.
Thus, it regularly leaves the cold waters, in which it feeds in autumn, summer and spring, and goes to tropical waters, to reproduce..
The path that this species takes during migration can cover long distances. Thus a Megaptera novaeangliae recorded in 2002 in the Antarctic Peninsula, it was later identified in American Samoa, which implies an approximate distance of 9,426 km.
This trip is done at an average speed of 1.61 km / h, taking periodic breaks. For example, those traveling along the east coast of Australia, on their way to the feeding ground in Antarctica, make stops in the warm waters of Hervey Bay in Queensland..
This type of transoceanic displacement has also been evidenced in the northern hemisphere. Specialists have found genotype matches between the species that live in Colombia and those of French Polynesia. This shows the migration of the whale between those two continents..
During migrations, researchers have described segregation by reproductive class and age. Thus, in the southern hemisphere displacement, lactating females and their young are the first group to leave the Antarctic foraging zone..
Approximately 12 days later the young whales leave and between 20 and 23 days the females and mature males. Pregnant females migrate last, around 31 days after the movement has started.
On the return trip, the pregnant females, together with the young, leave the tropical waters first. Approximately 10 days later the males leave and at 16 days, the young and their mothers.
Previously, the displacements were associated exclusively with the photoperiod and the movement of the dams. However, recent studies indicate that these are due to a combination of elements
These factors include the female's hormonal status, body condition, seawater temperature, food availability, and photoperiod..
The population of Megaptera novaeangliae it has varied over time. Thus, in 1988, this species was considered in serious danger of extinction. However, in 1996 there was a remarkable recovery and the IUCN classified it as vulnerable..
In 2008, said protectionist organization changed its status to Least Concern. This is because most populations have recovered, although some populations in the United States are at risk of extinction..
Years ago, commercial hunting of this species depleted their populations. However, this situation changed, thanks to its legal protection. Thus, there are substantial increases in the North Pacific, the Southern Hemisphere and the North Atlantic..
One of the main problems afflicting the humpback whale is its accidental capture, since it becomes entangled in fishing gear. This could seriously injure your body or cause you to drown..
Other threats are collisions with boats and noise pollution, which cause a large number of deaths..
This species, like the rest of the cetaceans, orients itself using its auditory sense. When exposed to high noise levels, they can suffer damage at the level of the ear, leading to disorientation and possible collision with ships..
Some of the polluting activities are gas and oil exploitation, explosives tests and active sonars. Also, the noise of the engines of the boats can have serious consequences for this animal.
Since 1955, globally, the humpback whale has been protected from commercial hunting. Adding to this, in various nations there are protected natural areas, such as sanctuaries.
What's more, Megaptera novaeangliae It is included in Appendix I of CITES, so its capture for commercialization is prohibited, with the exception that this is for other purposes, such as scientific research..
The National Oceanic and Atmospheric Administration established speed restrictions for vessels to prevent them from colliding with whales. Likewise, it works hard to develop methods that prevent whale entanglement in fishing nets..
The female reaches sexual maturity at 5 years, when it measures between 11 and 13 meters in length. As for the male, they are mature at 7 years, a stage in which they have an approximate length of 10 to 12 meters.
Although a male is sexually mature, specialists indicate that it is highly unlikely that he will be able to reproduce successfully until he is physically mature. This could happen between the ages of 10 and 17.
The sexually mature male exhibits an increase in the weight of the testes and in the rate of spermatogenesis. On the other hand, in the female, the weight of the ovaries remains relatively constant. Generally, ovulation occurs only once in each mating period..
The humpback whale has a polygamous mating system, where males compete for access to females in heat. During copulation, the female and the male swim in a line, to then participate in the rolling and flipping movements of the tail..
Following this, the pair dive and emerge vertically with their ventral surfaces in close contact. Then they fall back into the water.
Mating occurs during the winter migration stage, in search of warmer waters. As for gestation, it lasts approximately 11.5 months and birth occurs in the subtropical and tropical waters of each hemisphere..
The newborn is between 4 and 5 meters in length and weighs around 907 kilograms. This is breastfed by the mother, who provides him with a milk that contains high proportions of protein, fat, water and lactose. This makes it a nutritious food, which contributes to its rapid growth..
The time at which the calf is weaned and independent can vary. However, generally the calf begins to stop being breastfed around 5 or 6 months and at 10 months they already eat alone and are separated from their mother.
There is probably a transitional stage between feeding based on breast milk and solid food. In this period, beards increase in size.
By the time the calf is one year old, it has already doubled in size. After this time, the growth rate decreases, but the head area increases, taking into account the rest of the body..
The humpback whale is a widespread and opportunistic feeder. The basis of their diet is made up of euphausiids (krill) and small fish, including the Japanese sand eel (Ammodytes spp.), the capelin (Mallotus villosus), herring (Clupea spp.) and mackerel (Scomber scombrus).
Those that inhabit the southern hemisphere, feed on various species of krill (Euphausia superba). Specialists estimate that this mammal consumes between 1 and 1.5 tons per day of this crustacean.
In the Pacific Ocean, the most consumed prey are the Pacific saury and the atka mackerel (Atka makerel). Also, the Megaptera novaeangliae of the Bering Sea and the North Pacific it usually feeds on krill, herring, capelin, mackerel and sandeel (Ammodytes americanus).
The humpback whale introduces large amounts of prey and water into its mouth, then closes it, expelling the water. At the same time, the food gets caught in the beards and is swallowed.
In this process, the tongue plays an important role, since it contributes to both the expulsion of water and the swallowing of food.
Specialists in the field have identified five eating behaviors. These are:
The Megaptera novaeangliae rises to the surface and swims in circles. In doing so, it strikes the water with its fins, thus forming a foam ring, which surrounds the prey..
Subsequently, he plunges under the ring, opens his mouth, and rises up in the center. This way you can capture the prey that are inside the ring. Then, they dive under the ring and resurface in the center with their mouths open, allowing them to capture the prey within the ring..
Another way to catch their food is while swimming vertically, through groups of plankton or fish. Sometimes he can make a variation, ramming the grouping sideways.
When this whale exhales underwater it creates clouds of bubbles, which form large interconnected masses. They drag a large number of prey. The humpback whale slowly swims to the surface, through the inner part of the cloud that formed.
After shallow diving and hitting the water several times, the whale repeats the same maneuver. This strategy allows the fish to be confused or immobilized, thus facilitating their capture..
This is formed when the Megaptera novaeangliae he is swimming underwater in the shape of a circle, while exhaling air. The column can produce rows, circles or semicircles, which concentrate the prey.
In this technique, the humpback whale hits the surface of the sea with its tail one to four times. In this way it creates a network of bubbles that corners the fish. Then, said marine mammal enters the center of the turbulence and feeds.
In this video you can see how the humpback whale eats:
This species performs acrobatic jumps, coming out of the water with the body oriented upside down. Then he arches his back back and returns to the ocean, making a loud sound when he enters the water..
Another movement that characterizes the Megaptera novaeangliae it's when you do a deep dive. To do this, it hugs its back and rolls abruptly forward, exposing its tail out of the water..
The humpback whale is the most vocal of all the species in its genus. This cetacean does not have vocal cords, so the sound is produced by a very similar structure located in the throat.
Only the male vocalizes songs, which are long and complex. Each consists of a variety of low-register sounds, varying in frequency and amplitude. All species in the Atlantic sing the same melody, while those that live in the North Pacific emit a different one..
The purpose of these songs could be to attract the female. However, often other males tend to approach the one who is vocalizing, so if this situation occurs it could end in conflict. Likewise, some scientists propose the hypothesis that it fulfills an eco-locative function.
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