Whales are a group of fully aquatic placental marine mammals that are widely distributed and diverse.
Within the infra-order Cetacea, they are an informal group, typically excluding dolphins and porpoises. The order Cetartiodactyla, which has even-toed ungulates, refers to whales, dolphins, and porpoises. Hippopotamuses are their nearest living relatives, having diverged around 40 million years ago. Approximately 34 million years ago, the two parvorders of whales, baleen whales (Mysticeti) and toothed whales (Odontoceti), are believed to have broken apart.
Whales are open-ocean animals, fully aquatic, which feed, mate, give birth, suckle, and raise their young at sea. Whales vary in size from the dwarf sperm whale of 2.6 meters (8.5 ft) and 135 kilograms (298 lb) to the blue whale of 29.9 meters (98 ft) and 190 metric tons (210 short tons), which is the largest known species ever to live. The most giant toothed predator on earth is the sperm whale. Several species are sexually dimorphic since females are larger than males. There are no teeth for baleen whales; instead, they have baleen plates, a fringe-like device used to remove water while maintaining the krill and plankton they feed on.
To widen the mouth, they use their throat pleats to take in massive water gulps. Balaenids have heads to draw in water that can make up 40% of their body mass. On the other side, toothed whales have conical teeth that are adapted for capturing fish or squid. Baleen whales have a well-developed sense of “smell,” and toothed whales have a well-developed hearing, so well-developed is their hearing. Adapted to both air and water, that some can live even though they are blind. Some species are well suited to diving to great depths to capture squid and other preferred prey, such as sperm whales.
From land-living mammals, whales evolved. As such, whales must continuously breathe oxygen while they can stay for long periods submerged underwater. Some animals can remain underwater for as long as 90 minutes, such as the sperm whale. On top of their heads, they have blowholes from which air is taken in and expelled. They are warm-blooded, and under the skin, they have a layer of fat or blubber. Whales can run at up to 20 knots with streamlined fusiform bodies and two limbs adapted into flippers, but they are not as flexible or agile as seals. Whales create a great range of vocalizations, especially the humpback whale’s extended songs.
Most species prefer the calmer waters of the Northern and Southern Hemispheres. At the same time, whales are widespread and migrate to the equator to give birth. Without eating, animals such as humpbacks and blue whales can fly thousands of miles. Every year, males usually mate with several females, but females only mate every two to three years. In the spring and summer times, calves are typically born, and females accept responsibility for raising them. Mothers of some species spend one to two years fasting and nursing their young.
Once hunted for their goods endlessly, whales are now protected under international law. In the twentieth century, the North Atlantic right whales almost became extinct, with a population low of 450, and the IUCN lists the North Pacific grey whale population as Critically Endangered. They also face challenges from bycatch and marine pollution, in addition to whaling. Indigenous cultures of the Arctic have historically used the meat, blubber, and baleen of whales. In different cultures worldwide, whales have been portrayed, especially by the Inuit and coastal peoples of Vietnam and Ghana, who often perform whale funerals.
Occasionally, whales appear in literature and movies, as in Moby Dick’s great white whale of Herman Melville. Sometimes, small whales, such as belugas, are kept in captivity and trained to perform tricks. Still, breeding success has been low, and within a few months of capture, the animals sometimes die. Whale watching has become a form of worldwide tourism.
Whales are descendants of artiodactyl-order land-dwelling mammals (even-toed ungulates). They are associated with the Indohyus, an extinct ungulate-like chevrotain, from which they separated around 48 million years ago. About 49 million years ago, ancient cetaceans, or archaeocetes, first reached the sea and became fully aquatic 5-10 million years later. The appearance of anatomical features exclusive to cetaceans, alongside other primitive features not present in modern cetaceans, such as visible legs or asymmetric teeth, is what distinguishes an archdiocese. In the marine climate, their characteristics have been modified for living.
Their hearing set-up, which channeled vibrations from the jaw to the earbone, a streamlined body and the development of flukes on the tail, the migration of the nostrils to the top of the cranium (blowholes), and the transformation of the forelimbs into flippers, and the shrinking and eventual absence of the hind limbs, involved significant anatomical changes.
Now that you have learned about these humongous aquatic mammals, the next time you visit some aquarium, you’d know a little more than your companions!
