* Odontocetes: Toothed whales, which includes dolphins, porpoises, and other toothed whales like orcas.
* Mysticetes: Baleen whales, which includes humpback whales, blue whales, and other whales that have baleen plates instead of teeth.
Therefore, relatives of dolphins include:
* Other toothed whales (odontocetes) like porpoises, orcas, and other dolphin species.
* Baleen whales (mysticetes), which are also cetaceans but belong to a different suborder.
It's important to note:
* Porpoises are closely related to dolphins, but they have different physical characteristics, like a smaller, more rounded head.
* Orcas are the largest members of the dolphin family.
While dolphins are closely related to other whales, they are more distantly related to other mammals, like land mammals.