18. Fangtooth
Little is known about the fangtooth fish because of how deep it lives in the oceans; but one thing is for sure, it’s absolutely terrifying. The truth is they’re actually harmless to humans because of how little we actually come in contact with them and because of their small size. They usually only reach six inches but their teeth are so large for their bodies that they’ve adapted an extra pair of joints in their heads to be able to close their mouths.