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Some animals need to eat multiple times a day to get the energy required to survive. For example, an elephant can eat 375 pounds of vegetation every day. However, other animals have adapted to go long periods without food. They achieve this feat in various ways, from reducing their energy requirements to digesting their own body parts.
A variety of snakes, including vipers and constrictors, can survive for weeks, sometimes months, without eating. Because snakes are carnivores and hunt live prey, they cannot snack or slake their hunger pains by eating vegetation. Instead, they slow their metabolic rate by up to 70 percent when necessary to survive. Despite this huge reduction in metabolic activity, the snake will continue to grow. When the snake is able to find prey, he will gorge, potentially taking days to digest what he caught. Crocodiles are capable of going for more than a year without eating.
Insects and Arachnids
Cockroaches can survive without their head. A headless roach is capable of living for weeks. It is not the loss of its head that kills the roach, but the fact that he is unable to eat. With or without his head, the roach cannot go for more than a few weeks without eating, despite being cold-blooded -- a common trait among the most impressive food abstainers. Tarantulas, too, can last for more than a month without eating. Provided they are healthy, one meal can sustain a tarantula for several weeks without showing any ill effects.
While humans, dogs, elephants and a variety of other warm-blooded animals eat daily, other animals have adapted a famine and feast approach to food. Great white sharks can go for weeks without eating a single thing. The longer one of these apex predators goes without food, the more opportunistic their hunting strategies become. The record holder for the longest fast, though, is the lungfish. The lungfish may hibernate for up to four years. During this period, he will begin to digest his own muscle tissues. This process, a type of auto-cannibalism, is called autophagy.
The emperor penguin is one of the few warm-blooded animals to go for weeks without eating. Due to the harsh winters they face on the Antarctic ice, they have adapted to survive without food for up to two months while traveling to open water or broken ice in which to hunt. However, unlike crocodiles and snakes, they do not compensate by slowing down their metabolism. Instead, they survive on the fat reserves built up during the last period of feeding. Hibernating mammals, such as bears and hedgehogs, also build up deposits of fat to see them through months of winter sleep.
- Sea World: Elephants
- Live Science: How Snakes Survive Months Without Food
- Scientific American: Fact or Fiction? A Cockroach Can Live without Its Head
- PBS: Shark Attack
- PBS: Supersize Crocs
- National Geographic: Emperor Penguin
- Ask Nature: Surviving Extended Confinement -- Lungfish
- The British Tarantula Society: Keeping Tarantulas -- The Basics
- Polar Bears International: Hibernation and Denning
- Comstock/Stockbyte/Getty Images