Megaptera novaeangliae - Whale - Humpback whale - Who is the humpback whale and how does it live
THE MEGATTERA WHALE
Common name: humpback whale
- Body length: female: up to 14 m; male: up to 17 m
- Weight: 35 - 45 t
- Lifespan: up to 70 years
- Sexual maturity:45 years
HABITAT AND GEOGRAPHICAL DISTRIBUTION
The humpback whale, scientific name Megaptera novaeangliae of the family Balaenopteridae (alternative Balaenopteridae) is considered a cosmopolitan species present in all ocean basins from polar waters to tropical waters, from the Atlantic Ocean to the Pacific Ocean, including the Bering Strait.
They are cetaceans that follow the rhythm of the seasons, spending spring, summer and autumn in the polar seas in search of food, while with the arrival of winter they migrate to reproduce in tropical warm waters. The groups of humpback whales that spend the summer in the waters of the North Atlantic generally migrate to the waters of the West Indies and south-central Africa; those, on the other hand, which normally live in the North Pacific, usually overwinter in the warm waters of Mexico and Central America.
Humpback whales have also been spotted in the Mediterranean Sea but are considered only as guests, as they do not stop, they are just passing through.
CHARACTER, BEHAVIOR AND SOCIAL LIFE
The humpback whale is a social animal that lives in small groups that migrate seasonally from the pole where they go to feed, to tropical waters to mate and reproduce. They are therefore migratory animals: in spring, summer and autumn they live in the waters of the poles and spend time feeding while in winter they go to the warm waters of the tropics where they mate and then give birth to their young.
It has been observed that the humpback whale tends to give violent blows in the water with its pectoral fins and to make great dives by lifting itself out of the water and then throwing itself back on its back (see video on the side). It is not known exactly the meaning of this ritual, perhaps they are signals for the other members of the group.
The humpback whale with its young can also become aggressive when another whale alien to its group approaches.
The humpback whale is easily identified with respect to other whales due to its pinniform forelimbs and the presence of a small hump in front of the dorsal fin.
The body is usually dark blue or slate gray in both the dorsal and ventral parts. The ventral part can also be flecked with white or dappled.
Another peculiarity of the humpback whale is the throat provided with numerous skin folds (about 12-36) along the length of the body that allow the humpback whale to expand the throat to contain more food. They are also equipped with small nodules (tubercles) of a few centimeters in diameter that cover the lower jaw and the head. Each tubercle has a gray hair that is thought to have sensory functions such as the whiskers of cats.
The pectoral fins are very large and are about 1/3 the length of the body long and have an irregular and gnarled edge and are white in the Atlantic humpback whales while they are black above and white below in those of the Pacific Ocean and the hemisphere. southern. The caudal fin is horizontal, with serrated edges and white below with different designs depending on the individual.
During the migrations they keep an average pace of 3-14 km / h but can also reach 27 km / h. In general, mothers with babies are much slower than those traveling alone.
The humpback whale has two blowholes that are used by the whale to breathe. During the exhalation from the vents gushes a jet of water that can reach a height of 3 m. It can stay submerged for up to twenty minutes.
The eyes are small, suitable to withstand the great sea pressures.
They are cetaceans completely devoid of teeth (on the contrary, for example of the orcas, the latter in fact belong to the suborder of the Odontocetes) but provided with baleen. These are dark-colored horny laminae, which are located on the sides of the jaws of a horny consistency, each measuring about 65 cm and appearing as a sort of fringe.
Humpback whales are animals that communicate with each other with gurgling, screeching, moaning. Beyond that, body language is also very important in fact sometimes they jump out of the water and then dive causing a lot of noise and splashes; other times they beat their tails in the water. It is not known precisely what the meaning of this gesture is but they could be signals to the other members of the group.
A humpback whale needs about a ton of food a day to store enough fat to cope with a winter fast.
When hunting, she can be alone or in a group, preferring schools of small fish and krill (1).
The humpback whale uses different fishing techniques:
- when the food is abundant and sees a shoal on the surface it approaches from below or sideways with the mouth open ingesting water and fish: the water is expelled through the baleen while the fish is swallowed with the help of the tongue;
- foam technique: the humpback whales swim on the surface in a circle hitting the water not the fins thus creating foam that scares the fish that consequently gather on the surface; at that point the humpback whales quickly dive to re-emerge with their mouths open among the fish;
- the bubble technique: two humpback whales see for example a shoal of anchovies; they rise from the bottom of the sea towards the surface with a spiral movement causing numerous air bubbles which, rising to the surface, surround the anchovies. These frightened ones cluster on the surface and at that point the humpback whales head towards the reef not their mouths wide open (see video below).
These are just some of the techniques adopted and are not to be considered in the strict sense that is to say that they are often combined according to the situations and needs.
REPRODUCTION AND GROWTH OF SMALL
The mating of the humpback whale occurs in tropical warm waters as well as the birth of the young.
An important aspect is courtship. It has been observed that a male sings a kind of song that can be heard even several kilometers away. It is not certain if this song serves to attract the female, it has only been noted that when the female approaches, the male stops singing.
Fights between males over a female are not uncommon: the two males face each other head-on and violently flap their fins.
The gestation of a humpback whale lasts about a year at the end of which only one small 4-5 m long is born that is suckled by the mother continuously for about 5-6 months sucking about 550 liters of milk per day. After this period he is weaned but continues to remain with his mother for about a year. The males do not participate in any way in the rearing of the young.
Sexual maturity is reached around 4-5 years and generally the female enters estrus every two to three years.
STATE OF THE POPULATION
The humpback whale is listed on the 2009 IUNC Red List as low risk of extinction LEAST CONCERN (LC) as recent estimates have evaluated a number of specimens equal to 60,000 individuals, therefore above the criteria necessary to classify it as vulnerable as well.
The humpback whale has been protected from commercial hunting in the North Atlantic by the IWC (International Whaling Commission) since 1955, in the global South since 1963 and in the North Pacific since 1966. The latest commercial catches date back to 1968. Despite being a species that has been heavily hunted (to obtain oil for lighting or as a lubricant, flesh and bones to obtain fertilizer) today its population is in clear recovery. They also enjoy additional protections, having been established several sanctuaries in some countries of the world.
The species is listed in Appendix I of CITES (Convention on International Trade in Endangered Species of Fauna and Flora, known simply as the "Washington Convention" which includes endangered species and the trade in specimens of these species is allowed only in exceptional cases) and in Appendix I of the CMS (Convention on the Conservation of Migratory Species of Wildlife, also known as the Bonn Convention, which lists migratory species that have been classified as endangered in whole or in part significant of their area and against which States must work to protect the conservation or restoration of the habitats in which they live, also mitigating the obstacles to their migration).
Today only a few specimens are hunted in the world. Japan, the largest whale hunter, has suspended humpback whale hunting for 2009.
Another major threat to the humpback whale is ongoing activities along the coasts of Brazil, Gabon, Angola, Mozambique and Madagascar where a number of offshore oil and gas programs are taking place, with potentially impacts. negative effects on the whole ecosystem.
Often the humpback whale is injured by ships or boats as well as accidentally caught with fishing nets.
The name megaptera comes from the Greek mega "Big" e pteron «Wings» due to the pectoral fins which look like wings as they are very long (almost a third of the length of the body), the longest of all cetaceans.
To hear the noises emitted by this animal, go to the article: The sounds made by the humpback whale
- It is a large concentration (up to tens of thousands per cubic meter of water) of small marine crustaceans similar to shrimps (belonging to the order of the Euphausiacea) which are found in the spring - summer period in the glacial seas and which constitute the food base of different whale species. Krill is also exploited as a food resource in some countries, such as Russia and Japan which actively fish for it, unfortunately stealing a precious food from the survival of many whales and for this reason many international organizations and bodies are trying to regulate this fishing around the world. .