 As of 2013 , the International Union for Conservation of Nature ( IUCN ) recognized 86 cetacean species , 40 of which are considered whales . Six are considered at risk , as they are ranked Critically Endangered ( the North Atlantic right whale ) , " Endangered " ( blue whale , fin whale , North Pacific right whale , and sei whale ) , and " Vulnerable " ( sperm whale ) . Twenty @-@ one species have a " Data Deficient " ranking . Species that live in polar habitats are vulnerable to the effects of recent and ongoing climate change , particularly the time when pack ice forms and melts . 
