Balaenopteridae

Balaenopteridae is a family of baleen whales, commonly known as rorquals, within the baleen whales (Mysticeti). They include some of the largest animals in the world and are important marine predators and ecosystem indicators. The family comprises two main genera, Balaenoptera and Megaptera, though some taxonomic treatments place Megaptera within Balaenoptera as a subgenus.

Rorquals are characterized by their slender bodies, long pectoral fins, and a series of longitudinal ventral throat grooves that enable dramatic expansion when feeding. They have relatively small dorsal fins placed far back on the body, and they possess baleen plates for filtering prey from the water. Size varies by species; blue whales are the largest, exceeding 25-30 meters, while some minke whales are considerably smaller.

Balaenopteridae species are found in all the world's oceans, from polar to tropical regions, with many engaging in long seasonal migrations between feeding grounds and warmer birthing areas. Their diet consists mainly of krill and small schooling fish, captured through lunge feeding that involves rapidly accelerating through dense prey patches and filtering water through baleen plates. Humpback whales (Megaptera novaeangliae) are particularly noted for surface behaviors such as breaching and tail-slapping.

Conservation status varies by species; these whales were heavily exploited by commercial whaling in the 19th and 20th centuries. Today they are protected under international agreements, though they continue to face threats including entanglement in fishing gear, ship strikes, and climate-related changes in prey availability. Ongoing monitoring seeks to track population trends and recover threatened populations where feasible.