Being a large rorqual whale, it is the second existent largest animal, reaching more than 20 meters in length. The mouth has baleen in place of teeth, and in the posterior third of the body it shows a backswept dorsal fin. Displaying a dark-grey dorsal side and a white ventral side, the animal shows an asymmetric detail consisting of a lower dark left hemi-mandible and a white right one. These whales feed on small crustaceans and fish, being an oceanic species present in all oceans. With complex population dynamics, there are both migratory animals and resident populations. They are frequently seen off the coast of mainland Portugal throughout the year. It is the second most common whale species known to strand along the Portuguese mainland coast.