Whale

Whales are a diverse group of fully aquatic mammals that live in oceans around the world. They belong to the group of animals known as cetaceans, which also includes dolphins and porpoises. Whales come in many sizes, from the small dwarf sperm whale to the enormous blue whale, which is the largest animal known to have ever lived.

Baleen whales, such as the blue whale and humpback whale, feed on tiny creatures like krill and plankton using special plates called baleen. Toothed whales, like the sperm whale, have teeth and hunt fish and squid. All whales must return to the surface to breathe air through blowholes on top of their heads.

Whales were once hunted for their blubber and other body parts, but international laws now protect most species. However, they still face dangers from getting caught in fishing nets and pollution. People all over the world admire whales, and whale watching has become a popular tourist activity.

Etymology and definitions

The word "whale" comes from the Old English hwæl, which means "large sea fish". This word is not related to the country of Wales.

Sometimes people use the word "whale" to talk about dolphins and porpoises too. Some dolphins, like the orca or killer whale and the melon-headed whale, even have "whale" in their names. There are special groups of whales called "Great Whales", which include big whales like sperm whales and blue whales.

Taxonomy and evolution

See also: List of cetaceans and List of extinct cetaceans

Phylogeny

Whales belong to a group of mammals called Laurasiatheria. They are part of a group known as Cetacea, which also includes dolphins and porpoises. There are two main groups of whales: baleen whales, who use a special sieve-like structure in their jaws to filter food from the water, and toothed whales, who have sharp teeth for hunting.

Evolution

Main article: Evolution of cetaceans

Whales evolved from land-dwelling mammals that are related to even-toed ungulates, such as the Indohyus. About 48 million years ago, these animals began to live in the sea. Over time, they developed features that helped them swim and live underwater, like a streamlined body shape, flukes on their tails, and blowholes on top of their heads. Today, the closest living relatives of whales are hippopotamuses. Whales divided into two main groups, baleen whales and toothed whales, around 34 million years ago.

Biology

Whales are large, fully aquatic mammals with torpedo-shaped bodies. They have non-flexible necks, flippers instead of limbs, and large tail fins. Their skulls are flat with small eye orbits and eyes on the sides of their heads. Whales range greatly in size, from the small dwarf sperm whale to the enormous blue whale, which is the largest creature on Earth.

Whales breathe through blowholes on top of their heads, releasing a spout of air before inhaling fresh air. They have thick blubber for insulation, protection, and energy storage. Their teeth or whalebone (depending on the species) are specially adapted for their diet. Whales use their flippers for steering and their tail fins for propulsion, allowing them to swim at high speeds. They can dive deep by slowing their heart rates and storing oxygen in special body tissues.

Whales have adapted ears for underwater hearing and can produce a variety of vocalizations, including loud songs and clicks used for communication and navigation. Many species display intelligent behaviors such as teaching, learning, and cooperating. They give birth to live young and nurse their calves with rich, fatty milk. Most whales migrate long distances between feeding and breeding grounds. Unlike many animals, whales must stay conscious to breathe, and they have special ways of resting without drowning.

Main article: Cetacean intelligence

See also: Cetacean surfacing behaviour

See also: Right whale § Courtship and reproduction

Further information: Sleep in animals

Ecology

Whales are carnivores, meaning they eat meat. Some whales, like the blue whale, mostly eat tiny creatures called krill, while others, like the sperm whale, prefer squid. Whales usually hunt alone, but sometimes they work together in small groups to catch more food.

When whales die, their bodies sink to the deep ocean and become homes for many sea creatures. This process, called a "whale fall," supports a wide variety of marine life for many years.

Relationship with humans

Whaling

Main articles: Whaling and History of whaling

Whaling has been practiced by humans since ancient times. Early whalers used harpoons to hunt whales from boats. Different cultures, such as the Inuit and the Basques, developed their own whaling traditions. In the 18th and 19th centuries, whaling became a major industry, with whales being hunted for their oil, baleen, and ambergris. Today, a few countries still practice whaling, and some indigenous groups continue to hunt whales for subsistence.

Other threats

Further information: Cetacean bycatch, Cetacean stranding, and Marine mammals and sonar

Whales face several threats from human activities. They can get caught in fishing nets, which can harm or kill them. Pollution, especially from chemicals and plastic, also affects whales. Sonar used by ships can disturb whales and sometimes cause them to strand on shore. Collisions with ships are another danger, especially for species like the North Atlantic right whale.

Conservation

Efforts to protect whales have been underway since the mid-20th century. The International Whaling Commission has set limits on whaling and established sanctuaries to protect whale populations. Some whale species have recovered, while others remain endangered. Climate change poses a new threat to whales, especially those that live in polar regions.

Whale watching

Whale watching has become a popular tourist activity, with millions of people enjoying it each year. This industry provides income for many communities but also requires careful management to avoid disturbing the whales. Whale watching can coexist with conservation efforts when done responsibly.

In myth, literature and art

Further information: Biomusic § Whale song in music

Whales have inspired many cultures and artists throughout history. They appear in myths, religious stories, and works of literature and art. For example, the story of Jonah and the whale is well-known, and whales have been featured in famous books and films. Whales continue to capture the imagination of people around the world.

In captivity

Main article: Cetaceans in captivity

Further information: Beluga whale § Captivity

Some whales, like belugas, have been kept in captivity in aquariums and other facilities. These animals are often caught from the wild, and keeping them in tanks can be challenging. Researchers have also studied whales to understand their abilities, such as with sonar. While captivity can provide opportunities for education, it also raises questions about the well-being of these intelligent animals.