Fins
Fin skeletons are elongated and supported with soft and unsegmented rays named ceratotrichia, filaments of elastic protein resembling the horny keratin in hair and feathers.[32] Most sharks have eight fins. Sharks can only drift away from objects directly in front of them because their fins do not allow them to move in the tail-first direction.[30]
Dermal denticles
Unlike bony fish, sharks have a complex dermal corset made of flexible collagenous fibers and arranged as a helical network surrounding their body. This works as an outer skeleton, providing attachment for their swimming muscles and thus saving energy.[33] Their dermal teeth give them hydrodynamic advantages as they reduce turbulence when swimming.[34] Some species of shark have pigmented denticles that form complex patterns like spots (e.g. Zebra shark) and stripes (e.g. Tiger shark). These markings are important for camouflage and help sharks blend in with their environment, as well as making them difficult for prey to detect.[35] For some species, dermal patterning returns to healed denticles even after they have been removed by injury.[36]