CLASSIFICATION: Humpback whales (Megaptera novaeangliae) are baleen whales (Suborder Mysticeti). They are one of 76 cetacean species, and are marine mammals. Kingdom Animalia (animals) Phylum Chordata (vertebrates) Class Mammalia (mammals) Order Cetacean (whales and dolphins) Suborder Mysticeti (baleen whales) Family Balaenopteridae Genus Megaptera Species novaeangliae
GENERAL DESCRIPTION: The humpback whale is a baleen whale that sings amazing songs. It performs complex and cooperative feeding techniques. The humpback has a bulky head with bumpy protuberances (tubercles), each with a bristle. Humpbacks are acrobats of the ocean, breaching and slapping the water. They live in pods and have two blowholes. The name humpback describes the motion it makes as it arches its back out of the water in preparation for a dive.
SIZE: Humpback whales grow to be about 12-15 metres long, weighing 25-40 tons. The females are slightly larger than males, as with all baleen whales. The four-chambered heart of the average humpback whale weighs about 195 kg about as much as three average adult human beings.
LIFE SPAN: Humpback whales have a life expectancy of about 45-50 years, although some researchers suggest it may be double this figure.
SKIN, SHAPE AND FINS: Humpbacks come in four different color schemes, ranging from white to gray to black to mottled. There are distinctive patches of white on the underside of the flukes (tail). These markings are unique to each individual whale, like a fingerprint. The humpback’s skin is frequently scarred and may have patches covered with barnacles. Humpback whales have 14-35 throat grooves that run from the chin to the navel. These grooves allow their throat to expand during the huge intake of water during filter feeding. They have small, round bumps on the front of the head (called knobs or tubercles),and edging the jaws. Humpbacks have huge, mottled white flippers with rough edges that are up to one-third of its body length; these are the largest flippers of any whale. The humpback’s genus, Megaptera, means “huge-wings,” referring to its flippers. The flippers may have barnacles growing on them. The deeply notched flukes (tail) are up to 3.7 metres wide (12 feet). Humpbacks have a small dorsal fin toward the flukes.
DIET AND BALEEN: Humpback whales (like all baleen whales) are seasonal feeders and carnivores that filter feed tiny crustaceans (krill- mainly Euphausia superba, copepods, etc.), plankton, and small fish (including herring, mackerel, capelin, and sandeel) from the water. They are gulpers (not skimmers); filter feeders that alternatively swim then gulp a mouthful of plankton or fish. Concentrated masses of prey are preferable for this method of feeding. An average-sized humpback whale will eat 1000-1500 kg of plankton, krill and small, schooling fish each day during the feeding season in cold waters (about 120 days). Humpbacks cooperate in hunting and have developed a method of rounding up highly concentrated masses of prey that is called bubble-net feeding. The hunting members of a pod form a circle 3-31 metres across and about 15 metres under the water. Then the humpbacks blow a wall of bubbles as they swim to the surface in a spiral path. The cylindrical wall of bubbles makes the trapped krill, plankton, and/or small fish move to the surface of the water in a giant, concentrated mass. The humpbacks then eat a large, hearty meal. The humpback whale has about 330 pairs of dark gray baleen plates with coarse gray bristles hanging from the jaws. They are about 0.6 metres long and 34 cm wide.
SOCIAL GROUPS: Humpbacks travel in large, loose groups. Most associations between humpbacks are temporary, lasting at most a few days. The exception is the strong and lasting bond between mother and calves.
DIVING, BREACHING, SPY HOPPING, AND LOB TAILING: Humpback whales can dive for up to 40 minutes, but usually last only up to 5-15 minutes. Humpbacks can dive to a depth of 150-210 metres. Humpbacks are very acrobatic, often breaching high out of the water and then slapping the water as they come back down. Sometimes they twirl around while breaching. Breaching is likely to be largely for communication, as the sound of a breaching whale travels a long way underwater,but may also be purely for play or be used to loosen skin parasites. Spy hopping is another humpback activity in which the whale pokes its head out of the water for up to 30 seconds to look around. Humpbacks also stick their tail out of the water into the air, swing it around, and then slap it on the water’s surface; this is called lob tailing. It makes a very loud sound. The meaning or purpose of lob tailing is unknown, but may be done as a warning to the rest of the pod. Humpbacks lob tail more when the seas are rough and stormy. Slapping a fin against the surface of the water is often seen in courting behaviour.
SPOUTING – BREATHING: Humpback whales breathe air at the surface of the water through two blowholes located near the top of the head. They spout (breathe) about 1-2 times per minute at rest, and 4-8 times per minutes after a deep dive. Their blow is a double stream of spray that rises about 3 metres (10-13) feet above the surface of the water.
SPEED: Humpback whales normally swim 4.8-14 kph but can go up to 24-26.5 kph in bursts when in danger. Feeding speeds are slower, about 2 kph.
VOCALIZATION: Humpback whales are the noisiest and most imaginative whales when it comes to songs. They have long, varied, complex, eerie, and beautiful songs that include recognizable sequences of squeaks, grunts, and other sounds. The songs have the largest range of frequencies used by whales, ranging from 20-9,000 Hertz. Only males have been recorded singing. They sing the complex songs mostly in warm waters, possibly to attract females or to ward of other males. In cold waters, they make rougher sounds, scrapes and groans, perhaps used for locating large masses of krill (the tiny crustaceans that they eat).
HABITAT AND RANGE: Humpback whales live at the surface of the ocean, both in the Open Ocean and shallow coastline waters. When not migrating, they prefer shallow waters. They migrate from warm tropical waters where they breed and calve to polar waters where they eat. There are three separate populations of humpbacks, those living in the North Pacific Ocean, those in the North Atlantic Ocean, and those roving the oceans of the Southern Hemisphere.
MIGRATION: Humpback whales take long seasonal migrations. They mate and calve in tropical waters during the winter and then travel to cold polar waters during the summer to feed. During the summer in the warm waters, adults do not eat, but live off their layer of blubber (fat); the young calves feed on rich mother’s milk. Humpbacks migrate at 5-14 kph. They have incredible powers of endurance, travelling up to 8,000km each way during their annual seasonal migration, with almost no rest along the way. During migrations, they cover over 1,500 klm per month.
REPRODUCTION: Humpback whale breeding occurs mostly in the winter to early spring while near the surface and in warm, tropical waters. The gestation period is about 11-12 months and the calf is born tail first (this is normal for cetaceans) and near the surface in warm, shallow waters. The newborn instinctively swims to the surface within 10 seconds for its first breath; its mother, using her flippers, helps it. Within 30 minutes of its birth, the baby whale can swim. The newborn calf is about 4.3 metres and weighs about 2.5 tons. Twins are extremely rare (about 1% of births); there is usually one calf. The baby is nurtured with its mother’s milk and is weaned in about 11 months. The mother and calf may stay together for a year or longer. Calves drink 200 litres of milk each day. Humpback whales reach puberty at 4-7 years old and maturity at 15 years. A calf is born to a female every 1-3 years.
POPULATION: Humpback whales were targeted by commercial whaling. However in recent years their populations have recovered enough for them to be removed from the ‘Threatened’ category of the IUCN red list.