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In page Cetacea:

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Collective decisions are an important part of life as a cetacean for the many species that spend time in groups (whether these be temporary such as the fission-fusion dynamics of many smaller dolphin species or long-term stable associations as are seen in killer whale and sperm whale matrilines). [1] Little is known about how these decisions work, though studies have found evidence messy consensus decisions in groups of sperm whales and leadership in other species like bottlenose dolphins and killer whales.[citation needed]