Whales

Humpback Whale - Megaptera novaeangliae

There are approximately 80,000 Humpback Whales found in oceans and seas worldwide. In the North Pacific, about 18,000 to 20,000 have been found, over 12,000 in the North Atlantic and over 50,000 in the Southern Hemisphere. They are a large species, ranging from 12 – 16 meters in length and weighing 36,000 kilograms. It has a distinctive body shape with unusually long pectoral fins and a knobbly-looking head. Its four-chambered heart weighs about 195 kg, about as much as three average adult human beings. Being an acrobatic mammal, it breaches high with almost two thirds of its body out of water, sometimes even twirling around, then slaps the water as it comes back down. Humpbacks have also been known to spyhop, poking its head out of the water to have a look around. Its name ‘humpback’ describes the motion this whale makes in arching its back out of the water in preparation for a dive.

Male Humpback Whales produce beautiful, long and complex songs, lasting for 10 – 20 minutes and for hours at a time. It is thought they use these songs in mating as they sing them only in warm waters. In cold waters, they make rougher sounds, perhaps in order to locate large masses of their feed.

During the winter, these whales mate and produce calves in tropical waters, and then migrate to colder waters during the summer to feed. They travel at 3 – 9 miles per hour, over a distance of 3,100 miles with no rest at all. During their migrations, they cover about 1,000 miles per month. Their courtship rituals take place during the winter months, with competition being fierce. Groups of two to twenty males sometimes gather around a single female and produce a number of behaviours in order to establish the most dominant male whale. Their displays last for several hours, the group size growing and dwindling, as unsuccessful males retreat and others arrive. Behavioural techniques include spyhopping, lob-tailing, tail-slapping and flipper-slapping.

Humpback Whales give birth near the surface of the warm, tropical waters. Females produce offspring every 1 – 3 years of which the gestation period is approximately 11 – 12 months. Born tail first, it weighs about 2.5 tonnes, is about 4.3 meters in length and is nursed with its mothers milk for about 11 months of which it suckles 100 pounds of milk per day. After the first 10 seconds of its life, the newborn instinctively swims to the surface for its first breath, helped along of course by its mother using her flippers.

Their feeding takes place by means of bubble net feeding, whereby a group of whales blow bubbles to entrap their prey. They swim in smaller and smaller circles, then suddenly through the bubbles they swim with mouth wide open, swallowing their encircled and entrapped prey. These bubble rings can measure 30 meters in diameter. Humpbacks feed only in summer and live off their fat reserves during the winter. It hunts fish, such as krill, herring, salmon, mackerel and haddock by both direct attack, or by stunning them by hitting the water with its fins.