Adult crocodile/ alligator does not have nature predator?

The big cats (such as lions, tigers, leopards and jaguars) and the big snakes (green anaconda and reticulated python) can eat a small to medium sized crocodile or alligator. That is one reason alligators and crocodiles will dash towards the water when they are alarmed. In the water, they have no natural predators but a hippo can kill a crocodile in self defense. Hippos do not usually bother the crocodiles and a nudge by the hippo's snout is understood by the crocs that they should stay away. If not, and if baby hippos are around, then the hippo will not hesitate to kill the crocodile in defense of its baby. Some crocodiles are found in salt water, near coastal areas. These species may be vulnerable to attacks by large sharks or killer whales.