Digestive system of humpback whales stretching like an accordion. They allow whales to open their mandible to 90 degrees to gulp water and prey. They expel saltwater through the baleen plates, leaving behind krill and plankton. The whale's tongue plays a vital role in filter feeding, as it is used to push the water out of its mouth while keeping the prey trapped in its baleen bristles. As humpback whales do not have teeth, their food is swallowed whole and travels down the esophagus into the preliminary stomach (known as the forestomach) to be ground. Baleen whales have a multi-chambered stomach, divided into three distinct
Baleen baleen. These baleen bristles are arranged in plates across the upper jaw of the whale. As a material for various human uses, baleen is usually called whalebone. It is not to be confused (but often is) with whale bone or whale's bone meaning the actual bones of whales, used in carving, for cutlery handles and other uses for the bones of various large species. Like other bone materials, this often functioned as a substitute for ivory. Depending on the species, a baleen plate can be long, and weigh up to . Its hairy fringes are called baleen hair or whalebone-hair.