San Diego Zooさんのインスタグラム写真 - (San Diego ZooInstagram)「Whale what do we have here? Scientists used to think hippos were closely related to pigs and other ungulates, but as genetic research advanced they discovered that hippos are much more closely related to cetaceans—whales, porpoises, and dolphins. In fact, cetaceans are hippos’ closest living relatives. #WhaleofaDiscovery #WorthwhaleFact #HappyHippos #SanDiegoZoo Learn more about 🦛s ➡ bit.ly/HippoZOONOOZ」3月22日 6時24分