This means that, the size of a manta ray compared to a human, is typically three times larger, so if you’re manta ray diving in Maldives and a manta swims over your head, you’re going to feel very small. The manta rays size and swimming speed are its greatest defense mechanisms since it doesn’t have a sting in its tail. The biggest manta ray threat, apart from human beings, is whale shark, and in the event that a manta ray is attacked by a shark and survives, it will then visit a cleaning station for the small fish to eat away any dead skin or other residue left by the shark.