The upper jaw of the white shark is not fused to the skull. Instead, the jaws are slung loosely beneath the skull, held in place by flexible connective tissue and braced by accessory cartilages. Special muscles pull the jaw forward and down, riding on grooves on the undersurface of the skull. This arrangement allows this shark to protrude its jaws outward from the head, extending the reach of its teeth and creating a partial vacuum that helps suck in prey. This comes into play when one considers the teeth. The teeth have broadly triangular blades with coarsely serrated edges. The upper teeth are broader and flatter than the lower teeth, which reflects their different roles during biting. The lower teeth stab into and hold secure a food item while the saw-like upper teeth gouge out a hunk of flesh as the detached jaw extends forward and crashed down to meet the teeth holding the target in place. This dental arrangement allows the white shark to feed on prey too large to swallow whole as well as scoop out calorie-rich blubber from whale carcasses.
The two photos (by #WSV cameraman MJ Billen) featured here show how a white shark's upper jaw can appear almost toothless until the jaw moves forward and down to reveal the impressive teeth waiting within (image 2).