Shark Anatomy

Deadly Jaws

The shark's jaws exhibit characteristics unique in the animal world, no terrestrial predator has jaws that come anywhere near matching them in their perfection.

The ancestors of modern sharks were equipped with an upper jaw fixed to the skull (as in man) and with a mouth located at the extremity of the head.  Since the age of these fossil sharks, which had to content themselves with relatively small prey, the mouth has moved underneath the head, and the upper jaw, disengaged from the skull, has become mobile.  The shark is therefore equipped with two mobile and independent jaws, enabling it to swallow much larger prey and to tear off much larger pieces of flesh.

The spectacular distance these jaws can open would be nothing were they not subtended by muscles of exceptional power.  The shutting force of a shark's jaws was measured a few years ago using an apparatus tested by J. N. Snodgrass which he called the "gnathodynamometer".  With the help of Dr. Perry Gilbert he measured the dentitional strength of the Tiger Shark, the Lemon Shark and the Dusky Shark.  The maximum force recorded for for a single tooth of a Dusky Shark was 600 kilos per 2mm squared, or 3 tons per square cm.  Even then it should be noted that their specimens were not more than three meters long, so doubtless this enormous force must be doubled for animals of 5 or 6 meters in length.  As an indication, the strength exerted by a human jaw is 220 kilos per square cm for a man weighing 70 kilos (11 stone).  It must also be remembered that, in addition to cutting, these jaws are capable of crushing bones. ----