The fear of sharks took off only because of the movie Jaws, and though you shouldn't mess with them, sharks can often be very gentle and do not see humans as prey. Certain species are more aggressive, like Bull Sharks and Tiger Sharks, so it's important to know which species reside in the waters you're swimming in. Shark skin is made up of placoid scales that are essentially the same material as teeth, so very rough! Also, sharks have no bones. They are very ancient fish that only contain cartilage. The fear of sharks took off only because of the movie Jaws, and though you shouldn't mess with them, sharks can often be very gentle and do not see humans as prey. Certain species are more aggressive, like Bull Sharks and Tiger Sharks, so it's important to know which species reside in the waters you're swimming in. Shark skin is made up of placoid scales that are essentially the same material as teeth, so very rough! Also, sharks have no bones. They are very ancient fish that only contain cartilage.