Sea turtles can only protect themselves by trying to stay out of harm's way because unlike other types of turtles, they cannot retract their head or their legs back in to their shell. The sea turtle's shell is strong and can withstand a great deal of force, but the head and legs are vulnerable in any attack.
Sea turtles also hatch on beaches and must make it to the ocean without any predators getting to them. Once in the ocean, the sea turtles must fend for themselves and try to stay hidden as they grow. Scientists believe that sea turtles spend years growing and eating seaweed until they are big enough to begin reproducing and to avoid some of their predators.