How do predators feed themselves when they can no longer hunt?

 An old animal, whatever it may be, is nearing the end of its active life, and in the case of predators, this is less convenient because they often depend on their strength, speed, or agility to survive.

Nature is unforgiving, and even the king of the jungle meets his end. This old lion died of starvation after being driven from his pride in South Africa.

Sometimes, a large predator like a tiger, a leopard, or a cheetah gets injured for some reason, such as a fight or encounter with another aggressive species, like this other lion injured by a buffalo attack.

But as long as the injury or discomfort is not too serious, they can adapt and survive on smaller, easier-to-catch prey, as is the case with wolves who, although they prefer large prey, can also hunt rabbits, beavers or mice, or lions who can survive thanks to the hunts of their pack.

Small mammals like mongooses or civets are also very adaptable and can eat a variety of foods.

In 2017, this injured snow leopard was rescued in Qinghai province (northwest China); it had a lower back injury, so it couldn't defend itself and would almost certainly have starved to death.

Due to the eye injury, this cheetah cannot perceive distance and depth, so it is less efficient at hunting large prey. Healthy cheetahs already have a higher percentage of failure than success in hunting (50% or less successful hunt, compare with the African wild dog percentage of 70 to 90%).

Among wild felines, the small African black-footed cat is said to be the most efficient hunter, and it's not hard to imagine why, considering the lethality of our domestic cats, which are known to decimate wildlife in the wild when they become feral or semi-feral.

For birds of prey, any serious injury to the beak or wings can be catastrophic because they depend on them to hunt; this bald eagle, struck by a car on a Vancouver road, has no choice but to wait for human assistance.

The same is true for other large predators, such as crocodiles or large boas and pythons. Crocodiles sometimes have brutal encounters and end up with mutilated body parts or broken jaws.

This crocodile at the Chennai Zoo in India got into a fight with a companion and lost half of its upper jaw...

In general, reptiles are known to endure long periods without food: in this case, the captive animal did not eat and for a month received minced meat which it tasted occasionally (it was fed inadequately due to pain), unlike normal food where it receives large pieces of meat. A month and a half after the accident, it had fully recovered, and its deformity did not prevent it from living happily and comfortably in its enclosure.

Is there any creature on Earth that has no predators?

 If we take human beings into account, then no

If we exclude predators, then there are several animals without predators.

The pronghorn, the second fastest running animal, native to North America, is outrun by wolves and bears alike.

Let's go from north to south

Poison dart frogs. With a poison capable of killing an elephant with a single drop, or 60 humans, I don't think any predator would dare. This, combined with the fact that they protect their young, means there are no places to catch them without the poison nearby.

Due to their strength, intelligence, and the fact that they almost always live in pods, virtually no predator dares to attempt to hunt orcas.

Other candidates, but they really do have one or two, were: sea wasp, pufferfish, and elephants, rhinoceroses, and hippos.

What are the predators of crocodiles?

 By crocodile we are referring to only Crocodiles ( genus - Crocodylus), since Crocodilian family includes Crocodiles, Alligators and Gharials.

Some Crocodiles like Saltwater crocodile and Nile Crocodile are the largest large semi-aquatic reptiles alive today.

A fully grown 19.7 to 23 foot long, 2200 to 3500 pound fully grown Saltwater crocodile has almost no natural predator. Same for a 18 to 20 foot , 1500 to 2500 pound adult Nile Crocodile. Only predator of a large Saltwater crocodile or Nile Crocodile is another large rival crocodile. Crocodiles are feared for their massive jaws capable of huge bite force.

So what are the crocodiles’ natural enemies? -

Humans are the primary natural enemies of Crocodiles because till late 1970’s most of Crocodile population in the world was descimated by us for trophy hunting and their valuable armoured skin or hide.

If we are considering small and medium sized crocodiles. Bengal Tigers are threat for Mugger Crocodiles and medium sized Saltwater crocodiles especially in Indian subcontinent and parts of Sundarbans in Bangladesh. Mugger or Marsh Crocodiles are the most widespread of all crocodiles in India so they regularly confront Bengal Tigers. Indian rock python or Indian Tiger python too is natural enemy of Mugger Crocodile.

In some parts of Asia including India, Burmese pythons are also primary rivals of Saltwater crocodiles

Bulls sharks and Tiger sharks are also threat for medium sized Saltwater crocodiles in coastal waters.

In many parts of Northern territory of Australia, Sawfish and Bull sharks are primary rivals of Saltwater crocodiles.

Hippos and African Lions are primary enemies for Nile Crocodiles in Nile basin of Africa. Hippos are some of the few animals in African ecosystem that are capable of driving a fully grown Nile Crocodile from it's territory African Rock Pythons are also known to be rivals of Nile Crocodiles.

In Zambezi river, Bull sharks also known as Zambezi river sharks are primary rivals of Nile Crocodiles but are not match for these huge reptiles.

In Florida Everglades, American crocodiles face competition with invasive Burmese Pythons.

In parts of Amazon river basin, Amazon river systems particularly in Orinoco basin, endangered Orinoco crocodiles are rivaled by Giant Anacondas.