Whale than males. Baleen whales have no teeth; instead they have plates of baleen, a fringe-like structure used to expel water while retaining the krill and plankton which they feed on. They use their throat pleats to expand the mouth to take in huge gulps of water. Balaenids have heads that can make up 40% of their body mass to take in water. Toothed whales, on the other hand, have conical teeth adapted to catching fish or squid. Baleen whales have a well developed sense of "smell", whereas toothed whales have well-developed hearing − their hearing, that is adapted for both
Aetiocetus other edentulous, or toothless, mysticetes, the pattern of nutrient foramina is most similar to extant balaenopterids (blue whales and other rorquals) and fossil cetotheres. How did "Aetiocetus" feed, and what did it feed on? Its teeth are reminiscent of the bite-and-swallow strategy of archaeocetes and odontocetes, but they also possessed expanded palates. Modern mysticetes grow their baleen from this expanded palate and use the baleen to trap arthropods and fish in their mouths. This is known as bulk-feeding, in that the whale is not selecting individual prey items and does not use echolocation to find prey, as odontocetes do. Fossil