Fins have fins that can't fold down like those on other fish. Their fins have various special functions. Those aren't really the names of those fins, in case you were wondering. The big "scary" fin on top is the first dorsal fin and is used to balance the shark. The pectoral fins on the side help them steer and the caudal fin or tail fin help them to propel forwards. In addition to these, sharks have pelvic and anal fins.
Depending on the species, sharks either lay eggs (fewer than fish) or give birth to fully developed young. Shark egg cases vary in size and shape.