Bubble net feeding feed in a short amount of time. Humpback whales have a vertical throat roughly the size of a grapefruit. They cannot physically swallow anything larger than that. They are carnivores and primarily feed on small fish such as krill, juvenile salmon, and herring. They are also baleen whales, which means that they do not have teeth, so they must be able to eat things that they can swallow whole. They have several vertical grooves running down the length of their body so that they can hold large volumes of water and fish at one time. They feed for up to
Aetiocetus a family of toothless baleen whales, are contemporaneous with "Aetiocetus". Hence, whales whose feeding relied entirely on baleen made their stratigraphic appearance before "Aetiocetus", meaning that “true” baleen whales existed before "Aetiocetus". Baleen is made of keratin (the same material that comprises claws, hooves, nails, and hair) that grows throughout the whale's life. Development of mysticetes indicate that they had a toothed ancestor, as the fetal baleen whale forms tooth buds which are later reabsorbed and do not develop any further. However, "Aetiocetus" presents the evolutionary biologist with evidence for this transition in the fossil record. While baleen, as a