A dolphin is a marine mammal found throughout the world. They are toothed cetaceans and are thought to be among the most intelligent animals.
Pliny the Elder (a source for many medieval bestiaries) and Isidore both claim that dolphins use the sharp fins on their back to cut open the soft bellies of crocodiles in the Nile. They also make mention of the dolphin's ability to jump, with Isidore asserting that they can jump over ships that attack them. Pliny says that dolphins love music, which may be related to the dolphin's association with the Greek god Apollo.
The dolphin appeared on the arms of the heir apparent to the French throne, and the arms of the Florentine house of Pazzi features two dolphins.