Sawfish
Sawfishes, also known as carpenter sharks, are a family of rays characterized by a long, narrow, flattened rostrum, or nose extension, lined with sharp transverse teeth, arranged in a way that resembles a saw. They are among the largest fish with some species reaching lengths of about . They are found worldwide in tropical and subtropical regions in coastal marine and brackish estuarine waters, as well as freshwater rivers and lakes.
Smalltooth sawfish
The many teeth of a sawfish's saw are not actually teeth at all, but rather special types of scales known a dermal denticles. These protruding weapons, combined with the animal's ability to strike from side to side with great force, provide it with a powerful and efficient defense mechanism. Although the saw is mainly used for feeding purposes, observations of sawfish in captivity show that they may also be used for self-defense. When sharks or other marine creatures threaten them, they retaliate with three swift blows to the instigator's dorsum. Sawfish are not considered harmful to humans unless they are threatened.