means Sharks are cartilaginous fish — predators with skeletons of cartilage rather than bone — that have prowled the oceans for hundreds of millions of years.

from From Old English 'sceorc' or a related Germanic root, though the path is murky. The fish-name 'shark' surfaces in English in the 16th century, possibly borrowed from the Yucatec Maya word 'xoc' by sailors returning from the Caribbean — a charming theory that's plausible but unproven. It may instead be linked to German 'Schurke,' meaning a villain or scoundrel, which would explain why a 'shark' came to mean a greedy cheat as well as the beast itself.