The orca whale is the only one that is in the Orcuinus genus. But, the orca whale are related to other dolphins, whales, and porpoises.
Bottlenose Dolphin (Tursiops truncatus)
The bottlenose dolphins (Tursiops truncatus) is closely related to the orca whale. The bottlenose dolphin usually lives in warmer waters. They are grey in color. Like all dolphins they have a blowhole to get and release oxygen. They normally eat squids, eels, shrimp, and fish. They use echolocation to find prey. They are very smart, they use mimicry, able to recognize things and living creatures. Sometimes they help fishermen by driving fish into their nets. They will eat the fish which had not went into the nets. Some dolphins are trained to find sea mines. In Japan the dolphins are hunted to be eaten. Sometimes they dolphin get into nets meant for tuna. 
Irrawaddy Dolphin (Orcaella brevirostris)
The Irrawaddy dolphin (Orcaella brevirostris) is closely related to the orca, mostly gene wise. They are grey or dark slate blue; they have no pattern. The Irrawaddy dolphin lives in brackish waters near costs, mouths or rivers, and also in estuaries. They communicate by clicks, buzz, and creeks. The Irrawaddy has a a mutualistic relationship with us humans, especially with traditional fishers. the fishers give out a call for the Irrawaddy to drive fish into their nets. As a reward the fishers will give them some of their catch. They are being threatened by fishers further out of the coast. The fishers will let out their nets, most of the time the dolphin accidently drowns. They are also killed my blast fishing. Or they intentionally kill them for their oil.
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