The term 'bone whale' refers to two species of whales, the sei whale (Balaenoptera borealis) and the ORCA (Orcinus ORCA). The sei whale is a large baleen whale that can reach lengths of up to 18 meters and weigh up to 25 tons. It is found in all oceans and is listed as an endangered species by the International Union for Conservation of Nature. The ORCA, also known as the killer whale, is the largest member of the dolphin family and can reach lengths of up to 9 meters and weigh up to 6 tons. It is found in all oceans and is considered to be a top predator. Both species are highly intelligent and social animals, and have been studied extensively by scientists.