Toothed whale

Toothed whales, also called odontocetes, are a group of marine animals that includes dolphins, porpoises, beaked whales, and sperm whales. There are 73 different species of toothed whales. They are one of two main groups of whales, the other being baleen whales, which have baleen plates instead of teeth. Scientists believe these two groups separated about 34 million years ago.

Toothed whales vary greatly in size, from the small vaquita, which is about 1.4 meters long, to the massive sperm whale, which can reach 20 meters. They have streamlined bodies and flippers, and some can swim as fast as 30 knots. Their teeth are cone-shaped, perfect for catching fish or squid. These whales have excellent hearing that works both in air and water, so some can even survive without sight. Many toothed whales can dive deep, and almost all have a thick layer of fat called blubber to stay warm, except for river dolphins.

Toothed whales live in many parts of the world's oceans, though some species, like the vaquita, are found only in certain areas. They mainly eat fish and squid, but some, like the orca, also eat mammals such as seals. Females care for their calves, which are usually born in spring or summer, and in social species, the whole group helps raise the young.

In the past, whales were hunted for their products, but now international laws protect them. Many toothed whales are very intelligent. They still face dangers such as getting caught in fishing nets and pollution in the water. For example, the baiji, a type of whale, is almost gone because of pollution in the Yangtze River. Whales often appear in stories and movies, like in Herman Melville's Moby-Dick. Today, whale watching has become a popular form of tourism around the world. Some small toothed whales, mainly dolphins, are kept in special places where they perform tricks for people.

Taxonomy

Further information: List of cetaceans and List of extinct cetaceans

Research history

See also: Cryptid whale and Whale § In myth, literature and art

In the past, people thought whales were fish because they looked similar. But even early scientists noticed that whales had many features like land animals, such as blood and lungs. Over time, scientists learned more about whales, especially from studying dolphins that lived close to shore.

Evolution

Further information: Evolution of cetaceans

Toothed whales and baleen whales both came from land animals that walked on four legs. Their ancestor lived about 54 million years ago, and these animals began living in the sea around 49 million years ago. Toothed whales and baleen whales started to differ about 34 million years ago because of changes in the ocean.

Toothed whales developed a special skill called echolocation, which helps them find food even in the deep sea where there is no light. They make clicks that bounce off objects and return to them, helping them navigate and hunt. This ability allowed them to explore deeper waters and find new food sources.

Biology

Toothed whales have bodies shaped like torpedoes, with necks that don't bend easily. They have flippers instead of arms and legs, and no outer ears. Most have large heads, except for sperm whales. Their skulls are small, with eyes on the sides of their heads.

Toothed whales range in size from the small vaquita, about 4.5 feet long, to the huge sperm whale, which can be 20 meters (about 66 feet) long. They usually have teeth, unlike baleen whales, which have baleen instead. Some toothed whales, like dolphins, have many teeth, while others, like narwhals, have just one long tusk.

Toothed whales breathe by pushing air out of a blowhole on top of their heads, creating a spray of water vapor. This spray helps people identify different kinds of whales. They also have a thick layer of blubber under their skin, which helps keep them warm and safe.

Toothed whales can swim very fast, some reaching speeds of up to 35 kilometers per hour (about 22 miles per hour). They use their tail fins to move through the water and their flippers to steer. Many can dive deep into the ocean, holding their breath for long periods by slowing their hearts and storing oxygen in their muscles.

Toothed whales can see well underwater, even though their eyes are small. They can also use a special ability called echolocation to find their way and locate food. They make clicks and other sounds and listen for the echoes that bounce back from objects. This helps them "see" with sound, even in dark or murky water.

Main article: Animal echolocation § Toothed whales

Life history and behaviour

Intelligence

Main article: Cetacean intelligence

See also: Cetacean surfacing behaviour

Toothed whales are very smart animals. They can talk to each other, teach, learn new things, work together, and even feel sadness. Some dolphins have special brain cells that help them think and feel emotions, just like humans do.

These whales have big brains, which helps them be clever. For example, sperm whales have the biggest brains of any animal, even bigger than human brains. Dolphins also play a lot, like making rings of bubbles underwater and using tools to find food.

Vocalisations

See also: Whale song § Odontocete whales

Dolphins make many different sounds using special air sacs. They can make whistles, loud clicks, and other noises to talk to each other. Each dolphin has its own special whistle, kind of like a name, to identify itself. These whistles are important for dolphins to stay connected with friends, even after many years.

Sperm whales also make different sounds, like quick series of clicks to find food, and special patterns of clicks to talk to each other. Males make slow clicks, especially when they are looking for mates.

Foraging and predation

See also: Beluga whale § Predation

Toothed whales eat fish, squid, and other sea animals. They hunt in smart ways, like working together to herd fish into a tight group so they can eat more easily. Some dolphins even chase fish onto beaches to catch them.

Sperm whales dive deep into the ocean to find food, sometimes for over an hour. They mainly eat squid but will also eat fish and octopuses. Orcas, a type of toothed whale, hunt other whales and sea animals by working together in groups.

Life cycle

See also: Dolphin § Reproduction and sexuality

Toothed whales live their whole lives in the water. When a baby whale is born, it comes out head first so it doesn’t drown. The mother feeds the baby by squirting milk into its mouth. Baby whales drink this milk for about a year before they start eating solid food. Females take care of the babies, while males don’t help much with raising the young.

Interaction with humans

Threats

Sperm whaling

The head of the sperm whale contains a special waxy liquid called spermaceti. This wax can be made into useful products like candles, soap, and machine oil. People have hunted sperm whales for these valuable substances for many years.

In the past, hunting sperm whales was very dangerous for the people involved. Whales would sometimes fight back when hunted, which could harm the boats used in the hunt.

Drive hunting

Some dolphins and porpoises are hunted in an activity called dolphin drive hunting. This involves driving a group of dolphins into a bay or onto a beach where they cannot escape. This hunting happens in several places around the world.

Dolphins are mostly hunted for their meat, though some are kept in special places for people to see. Even though this hunting is controversial, it still happens in many places each year.

Other threats

Toothed whales can face other dangers from humans. They sometimes get caught in fishing nets by accident. Water pollution can also harm these whales, as they can absorb harmful chemicals from the water. These pollutants can make the whales sick.

Conservation

There are efforts to protect toothed whales around the world. Different groups work to safeguard these animals, though no single rule covers all of them. Some agreements focus on protecting whales in certain areas.

In captivity

Many toothed whales, especially dolphins, live in special places where people can visit them. Bottlenose dolphins are the most common in these places because they are easy to care for and friendly. Other types of whales are less common in these settings.

There has been debate about keeping these animals in captivity. Some groups worry about how well these animals are treated in these places.