With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: The killer whale is a freshwater shark.
text_B: The toothed whales -LRB- systematic name Odontoceti -RRB- are a parvorder of cetaceans that includes all the dolphins and porpoises , as well as the whales that have teeth , such as the beaked whales and sperm whales .. systematic name. systematic name. parvorder. parvorder. teeth. teeth. Seventy-three species of toothed whales -LRB- also called odontocetes -RRB- are described .. They are one of two living groups of cetaceans , the other being the baleen whales -LRB- Mysticeti -RRB- , which have baleen instead of teeth .. teeth. teeth. baleen. baleen. The two groups are thought to have diverged around 34 million years ago -LRB- mya -RRB- .. million years ago. million years ago. Toothed whales range in size from the 4.5 ft and 120 lbs vaquita to the 20 m and 55 MT sperm whale .. whale. whale. sperm whale. sperm whale. vaquita. vaquita. Several species of odontocetes exhibit sexual dimorphism , in that the females are larger than males .. sexual dimorphism. sexual dimorphism. They have streamlined bodies and two limbs that are modified into flippers .. Some can travel at up to 20 knots .. Odontocetes have conical teeth designed for catching fish or squid .. teeth. teeth. They have well-developed hearing , that is well adapted for both air and water , so much so that some can survive even if they are blind .. Some species are well adapted for diving to great depths .. Almost all have a layer of fat , or blubber , under the skin to keep warm in the cold water , with the exception of river dolphins .. blubber. blubber. Toothed whales consist of some of the most widespread mammals , but some , as with the vaquita , are restricted to certain areas .. vaquita. vaquita. Odontocetes feed largely on fish and squid , but a few , like the killer whale , feed on mammals , such as pinnipeds .. whale. whale. killer whale. killer whale. pinnipeds. pinnipeds. Males typically mate with multiple females every year , but females only mate every two to three years , making them polygynous .. polygynous. polygynous. Calves are typically born in the spring and summer , and females bear the responsibility for raising them , but more sociable species rely on the family group to care for calves .. Many species , mainly dolphins , are highly sociable , with some pods reaching over a thousand individuals .. Once hunted for their products , cetaceans are now protected by international law .. Some species are attributed with high levels of intelligence .. high levels of intelligence. cetacean intelligence. At the 2012 meeting of the American Association for the Advancement of Science , support was reiterated for a cetacean bill of rights , listing cetaceans as nonhuman persons .. American Association for the Advancement of Science. American Association for the Advancement of Science. nonhuman persons. non-human person. Besides whaling and drive hunting , they also face threats from bycatch and marine pollution .. whaling. whaling. drive hunting. dolphin drive hunting. The baiji , for example , is considered functionally extinct by the IUCN , with the last sighting in 2004 , due to heavy pollution to the Yangtze River .. baiji. baiji. IUCN. International Union for Conservation of Nature. Yangtze River. Yangtze River. Whales occasionally feature in literature and film , as in the great white sperm whale of Herman Melville 's Moby-Dick .. whale. whale. sperm whale. sperm whale. Herman Melville. Herman Melville. Moby-Dick. Moby-Dick. Small odontocetes , mainly dolphins , are kept in captivity and trained to perform tricks .. Whale watching has become a form of tourism around the world .. Whale watching. Whale watching
related.