Whales

Everything about these animals is huge. They can grow up to 33 metres long and weigh up to 190,000 kilograms. That's about as much as 30 elephants or 2,500 people. Their tongue alone weighs around 4,000 kilograms, and their stomach can hold 2,000 kilograms. A blue whale's mouth can hold 80,000 litres of water.

Blue whale calves are already seven metres long at birth and drink 250 to 500 litres of their mother’s milk each day. A blue whale’s heart is as big as a small car, and children could swim through its main artery. Their calls are louder than a jet taking off. They use these calls to communicate with other blue whales hundreds of kilometres away.

Blue whales are the largest animals on Earth and probably the largest ever to have lived on our planet. Some dinosaurs were gigantic too, but even the largest of them were much smaller and lighter than blue whales. These enormous animals can only live in water. On land, their hearts and lungs would be crushed by the weight and mass of their own bodies.

When they surface, they exhale stale air, sending a spout of water about 10 metres into the air. Their bodies are long and streamlined. Blue whales have a small dorsal fin, a broad tail fin and very long, narrow pectoral fins. Their backs are pale blue to grey, while their bellies are usually white or yellowish. 

They travel through the seas at speeds of up to 30 km/h. They can stay underwater for up to 20 minutes.

Blue whales are the largest whales on Earth. But they are just one of about 90 species. These are divided into two suborders: baleen whales and toothed whales.

Baleen whales are so called because about 600 fine plates of keratin, known as baleen, hang from their upper jaws. When a baleen whale is feeding, it takes a large amount of water into its mouth, along with as much krill and other small organisms as possible. Krill are small crustaceans that drift through the ocean in enormous swarms. The whale then closes its jaws and pushes the water out with its tongue. The krill gets caught in the whale’s baleen and is swallowed. A blue whale can filter up to 3.6 tonnes of krill from the water each day.

There are 14 other species of baleen whale on Earth. In addition to the blue whale, these include the humpback, fin, bowhead, sei and gray whales. Baleen whales are found in all the oceans. They feed in the cold waters of the Northern and Southern Hemispheres, migrating to warmer waters only at certain times. There they mate and give birth to their young.

Gray whales, for example, spend most of the year in the Arctic. However, their calves are born off the coast of Mexico or in warmer parts of the Pacific. About three months after giving birth, mothers and calves begin their journey back to the Arctic. Gray whales travel more than 10,000 kilometres in a year.

Whales breathe with lungs, not gills. So they have to surface from time to time to breathe. Baleen whales have two blowholes on top of their heads, through which they exhale stale air and inhale fresh air. The calls of the largest whales can be heard hundreds of kilometres away. Humpback whale songs are unique. All these sounds apparently help the animals communicate with one another.

There are about 70 species of toothed whales, including the many species of dolphins. Toothed whales have no baleen; instead, they have varying numbers of teeth. They have only one blowhole. The largest toothed whales are the sperm whale and the killer whale, also known as the orca.

Sperm whales have enormous, slightly rectangular heads. Large males can grow to over 20 metres long and weigh more than 50 tonnes. Sperm whales feed mainly on squid, cod, tuna and monkfish. Remains of giant squid, which live in the deep sea, have also been found in their stomachs. Sperm whales can dive to depths of up to 1,000 metres in search of prey.

Orcas grow to about 8 to 9 metres long and weigh around 6 tonnes. Their skin is strikingly black and white. They hunt fish, seals, seabirds, squid and sea turtles, and sometimes dolphins too. They join forces in groups when hunting.

Toothed whales also include belugas, for example, which are 3 to 6 meters long. They are closely related to the slightly smaller narwhals. Male narwhals develop a tusk that can grow up to three meters long and weigh eight to ten kilograms.

The smallest whales are harbour porpoises, which grow up to 2.5 metres long and weigh up to 200 kilograms. They are also found in the North Sea and the Baltic Sea.

Whales are not fish but mammals. All whale species give birth to live young, which their mothers nurse for several months after birth. Before giving birth, female whales usually migrate to warmer waters.

The amount of time that young animals develop inside their mothers varies greatly. The size they are at birth also varies. Blue whale mothers, for example, have their first calf at around five or six years of age. The calves grow inside their mothers for eleven months. At birth, they are seven meters long and weigh about 2,500 kilograms—roughly as much as 800 human babies. For the first 6 to 7 months of their lives, they feed on their mother’s milk.

Female sword whales have their first calf at 6 to 10 years of age. Calves are 2 to 2.5 meters long at birth and weigh around 200 kilograms. Female sword whales often go several years between births, so they have an average of 5 to 6 calves over their lifetime.

In earlier centuries, whales were hunted ruthlessly. When ships still sailed the world’s oceans under sail, whaling ships from Europe sailed to Greenland in the North Sea, where many whales were found. When a whale was spotted, the sailors lowered a rowboat into the water, and six to eight men pursued the animal.

They inflicted serious wounds on the whale with harpoons and lances until it eventually bled to death. The dead body was then dragged alongside the whaling ship. Out on the open sea, the crew boiled down the thick layers of blubber to make a substance known as whale oil.

Whale oil was used to keep lamps burning, as there was no electricity in those days. It was also used to make soaps, ointments, soups, margarine and leather care products. Whaling was a profitable business for ship owners. The captains and crews also earned good money. Their work was very dangerous, however. As ships and their equipment became more modern, many whales lost their lives. During the 20th century, whalers killed around three million whales—about 30,000 a year.

Since 1986, whaling has been largely banned under an international agreement. However, some exceptions have been allowed, and several countries have not signed the agreement. It is estimated that around 1,500 large whales are killed each year today, along with many more small whales and dolphins.