What are the mysticets?

“Mysticetes” is the scientific name given to baleen whales. It comes from the taxonomic category to which they belong, the suborder mysticeti . A taxonomic category is a set in which scientists group living things that have similar characteristics. Baleen whales fall into the following categories.

Kingdom: animal.
Division: vertebrates, because they have vertebrae and internal skeleton.
Class: mammals, because they have breasts to feed their young; they also have hair, down, or beards.
Order: cetaceans, because they are mammals adapted to aquatic life.
Suborder: mysticetes.

Characteristics of the mysticetes

The mysticetes are cetaceans that instead of teeth have beards located in the upper jaw. These beards are fringes of keratin that hang from the roof of the mouth and are supported by the upper gums. The baleen, organized in plates, form a filtering mechanism to consume large amounts of small fish, crustaceans or plankton in one gulp.

Mysticetes have a double spiracle, that is, two holes for breathing. They measure between 7 and 30 meters in length. They have a symmetrical skull and their ribs are not articulated to the sternum. In addition to the wattles, another distinguishing feature is that females are generally larger than males, with those from the southern hemisphere being even larger than those from the northern hemisphere.

Classification of the mysticetes

Although there are different criteria for their classification, four types of mysticetes are traditionally known, all called whales: true, pygmy, gray and rorqual whales.

True whales have a large head (which takes up almost a third of the body), a curved face, and smooth, black skin on the throat. They are called “true” because hunters attributed a large amount of oil and beards to this group.

Pygmy whales have a small head, which spans a quarter of the length of the body. They are the smallest of all mysticetes, reaching only 6.5 m in length. One of its distinctive characteristics is that the beards are yellowish.

Gray whales have a smaller head than true whales and a slightly curved rostrum. Their size is not as small as that of the pygmies, but they are not as big as the rorquals. They have an elongated mouth that seems to divide the head in two.

Fin whales are small-headed. They have a straight rostrum, throat skin with longitudinal folds (also called ventral grooves), and a relatively flat and broad upper jaw. They are the most common and studied of the whales, being representative the blue and the humpback.

Ecology

• Feeding. Mysticetes are strictly carnivorous; they feed on zooplankton and small fish. Depending on the species, they consume between 1.5 and 4.0% of their body weight.
• Relations with other species. The most notable predators of baleen whales are humans and killer whales. The mysticetes are commensals of species such as barnacles, which stick to their bodies; they are also hosts for different types of internal stomach and intestinal parasites.
• Longevity. The mysticetes are long-lived, that is, they can live for several years. The average lifespan is 50 years, although cases of up to 100 have been recorded.
• Migrations. Many baleen whales make long migrations and are fast swimmers. Although some species come close to the coast at some point in their lives, most of them inhabit and remain in the open sea. Humpback whales have been reported to be the mysticetes with the longest migration route, which runs from arctic waters to the coast of northern California.

singing whales

In mysticetes, the production of sounds has been associated with territorial behaviors and communication with young. Blue whales produce the highest sustained sound of any animal, while humpbacks emit long, complex song-like sequences made up of roars, moans, and groans.

Distribution

True whales are distributed in the North Atlantic. The gray ones, which during the 17th and 18th centuries were also abundant there, are now extinct; those that survive are located in the North Pacific. Pygmy whales are restricted to the southern hemisphere, where the waters are warm. Humpbacks have been identified in the North Atlantic and Pacific, in Hawaii and eastern Mexico; in the southern hemisphere they have been found in eastern Australia, New Celedonia, Fiji and in the Central Pacific.

some threats

Blue whales have been hunted almost to the brink of extinction. Other rorqual whales are endangered by fishing nets, water pollution and collision with boats. Due to the above, the conservation status of many endangered or endangered species.

Sources

Bannister, John L. Baleen Whales (Mysticetes) . In F. Perrin, William; Wursig, Bernd; Thewissen, JGM, eds. Encyclopedia of Marine Mammals. 2nd edition. Academic Press, 2008.

Howes, Gloria., Bahamonde, Paulina., Chiang, Gustavo. Didactic guide of cetaceans. Corcovado Gulf/Northern Patagonia/Chile. MERI Foundation, sf