Specifically, they belong to the suborder Odontoceti, which includes all toothed whales. This means they are related to other toothed whales like:
* Porpoises (though they are smaller and have a different body shape)
* Orcas (killer whales)
* Dalls porpoises
* Bottlenose whales
* Sperm whales
All these animals share a common ancestor and are part of the same larger group, the Cetacea order, which also includes baleen whales.