Atlantic mackerel
The etymology of the word "porbeagle" is obscure. A common suggestion is that it combines "porpoise" and "beagle", referencing this shark's shape and tenacious hunting habits. Another is that it is derived from the Cornish "porth", meaning "harbor", and "bugel", meaning "shepherd". The "Oxford English Dictionary" states that the word was either borrowed from Cornish or formed from a Cornish first element with the English "beagle". The "Dictionary" also notes that no evidence exists for a connection to the French "porc", meaning "swine", or to "porpoise", as has been proposed. Other common names for the porbeagle include Atlantic mackerel shark, Beaumaris shark, bottle-nosed shark, and blue dog.