Whales

Ever got wet by the smashing tail of a humpback whale?

An acrobatic animal known for breaching and slapping the water with its tail and pectoral fins, it is popular with whale watchers especially around Guinjata Bay from June up to November. (It’s so loud it even wakes you up at night.)

Humpback whale breaching at Guinjata Bay

Humpback whale breaching at Guinjata Bay

The humpback whale is a species of baleen whale. The larger species, adults range in length from 12–16 meters and weigh approximately 36,000 kilograms. The humpback has a distinctive body shape, with unusually long pectoral fins and a knobbly head.

Males produce a complex song lasting 10 to 20 minutes, which they repeat for hours at a time. Its purpose is not clear, though it may have a role in mating. You will especially here this song while on dives or even on ocean safaris.

Diving with whales in the Indian Ocean in Mozambique, Africa

Diving with whales in the Indian Ocean in Mozambique, Africa

Humpback whales typically migrate up to 25,000 kilometers each year. Humpbacks feed only in summer, in polar waters, and migrate to tropical waters to breed and give birth in the winter. During the winter, humpbacks fast and live off their fat reserves. Their diet consists mostly of krill and small fish. Humpbacks have a diverse repertoire of feeding methods, including the bubble net feeding technique.

A humpback whale can easily be identified by its stocky body with an obvious hump and black dorsal coloring. The head and lower jaw are covered with knobs called tubercles which are hair follicles, and are characteristic of the species.

The fluked tail, which it lifts above the surface in some dive sequences, has wavy trailing edges. The long black and white tail fin, which can be up to a third of body length, and the pectoral fins have unique patterns, which make individual whales identifiable. The two most enduring mention the higher maneuverability afforded by long fins, and the usefulness of the increased surface area for temperature control when migrating between warm and cold climates.

The dorsal fin is visible soon after the blow when the whale surfaces, but disappears by the time the flukes emerge. Humpbacks have a 3 meters heart-shaped to bushy blow, or exhalation of water through the blowholes. And can be visibly seen around Guinjata Bay, and Toffo area and up to as far as the equator. Because humpback whales breath voluntarily, the whales possibly shut off only half of their brains when sleeping.

Newborn calves are roughly the length of their mother’s head. At birth, calves measure 6 meters and weigh around 2 tons. The mother, by comparison, is about 15 meters. They nurse for approximately six months, and then mix nursing and independent feeding for possibly six months more. Humpback milk is 50% fat and pink in color.

Humpback Whale - Closeup eye to eye with Guinjata Dive Centre Mozambique

Humpback Whale – Closeup eye to eye with Guinjata Dive Centre Mozambique

Females reach sexual maturity at the age of five, achieving full adult size a little later. Males reach sexual maturity at approximately seven years of age. Humpback whale lifespan range from about 45–100 years. Fully grown, the males average 13–14 meters. Females are slightly larger at 15–16 meters. The female has a hemispherical lobe about 15 centimeters in diameter in its genital region. This visually distinguishes males and females. The male’s penis usually remains hidden in the genital slit.

The humpback social structure is loose-knit. Typically, individuals live alone or in small, transient groups that disband after a few hours. These whales are not excessively social in most cases. Groups may stay together a little longer in summer to forage and feed cooperatively. Longer-term relationships between pairs or small groups, lasting months or even years, have rarely been observed. Some females possibly retain bonds created via cooperative feeding for a lifetime. The humpback’s range overlaps considerably with other whales and dolphin species

Courtship rituals take place during the winter months, following migration towards Guinjata Bay, Jangamo and Tofo area to the equator from summer feeding grounds closer to the poles. Males gather into “competitive groups” and fight for females. Behaviors include breaching, spy hopping, lob tailing, tail slapping, fin slapping, peduncle throws, charging and parrying. Whale songs are assumed to have an important role in mate selection; however, they may also be used between males to establish dominance.

Females typically breed every two or three years. The gestation period is 11.5 months, yet some individuals have been known to breed in two consecutive years. The peak months for birth are January, February, July, and August, with usually a one- to two–year period between humpback births.
Both male and female humpback whales vocalize, but only males produce the long, loud, complex “songs” for which the species is famous. Humpbacks may sing continuously for more than 24 hours. Whales have no vocal cords, so whales generate their songs by forcing air through their massive nasal cavities.

Whales within a large area sing the same song. All North Atlantic humpbacks sing the same song, and those of the North Pacific sing a different song. Each population’s song changes slowly over a period of years without repeating.

Diving with humpback whale in Mozambique

Diving with humpback whale in Mozambique

Scientists are unsure of the purpose of whale songs. Only males sing, suggesting one purpose is to attract females. However, 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. Some scientists have hypothesized the song may serve an echo locative function. During the feeding season, humpbacks make altogether different vocalizations for herding fish into their bubble nets.

Humpback whales have also been found to make a range of other social sounds to communicate, such as “grunts”, “groans”, “thwops”, “snorts” and “barks”.
The worldwide population is at least 80,000 humpback whales, with 18,000–20,000 in the North Pacific, about 12,000 in the North Atlantic, and over 50,000 in the Southern Hemisphere.

Humpback whales are generally curious about objects in their environments. Some individuals, referred to as “friendliest”, approach whale-watching boats closely, often staying under or near the boat for many minutes. Because humpbacks are often easily approachable, curious, easily identifiable as individuals, and display many behaviors, they have become the mainstay of whale watching trip run from Guinjata Dive Center daily.

Humpback Whale breaching the surface in Guinjata Bay

Humpback Whale breaching the surface in Guinjata Bay

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