mysticetes

Mysticetes, or baleen whales, form a large suborder of the toothed-toothless cetaceans and include the majority of the world's largest animals. They are distinguished from odontocetes (toothed whales) by having baleen plates instead of teeth, which they use to filter prey from seawater. Living mysticetes comprise about 15 species in four families: Balaenidae (right whales), Balaenopteridae (rorquals such as blue, fin, sei, humpback, and minke whales, plus Bryde’s whale), Eschrichtiidae (grey whale), and Neobalaenidae (pygmy right whale).

Mysticetes feed by drawing water containing small prey into the mouth and then filtering it through baleen plates. Their prey is mostly small crustaceans such as krill and small fish. Feeding strategies vary: rorquals perform lunge feeding with extensible throat pleats that expand to take in large volumes of water, gray whales use benthic suction feeding along the seafloor, and right whales often feed by skim-feeding near the surface.

They range in size from several meters to more than 30 meters in length, have two blowholes, and often undertake long migrations between high-latitude feeding grounds and warmer tropical or temperate breeding areas. Reproduction involves long gestation periods (about 11–12 months), with calves born several meters long and nursing for several months.

Evolutionarily, mysticetes diverged from toothed ancestors and developed baleen as a primary feeding adaptation. They inhabit most of the world's oceans and play key roles in marine ecosystems, including nutrient cycling and prey population dynamics. Vocalizations are common in many species, with some producing complex songs during breeding seasons.

Conservation concerns stem from historical commercial whaling and ongoing threats such as bycatch, entanglement, ship strikes, and climate-driven changes in prey availability. International protection has aided recovery for some populations, but risks remain varied by species and region.