Nature is full of crazy creatures that defy all logic, and nothing is more astonishing than animals that can live to be older than humans. Some of the oldest animals in the world have lived since the time of Charles Darwin, and some survivors that may have been around during the time of the last mammoths. 

It's important to study these rare creatures as they (longest-lived animals) can teach us a lot about the aging process. Sometimes estimates are exaggerated, but age testing in these animals is very complex and relatively accurate.These ancient animals are believed to be some of the world's oldest things and, as technologies improve, we get a better understanding of them.

(Photo : Getty Images)

Ocean Quahog Lived For More Than 400 years 

In 2007, researchers examining a dead clam discovered that they may have accidentally killed one of the oldest creatures in the world. The Ming clam, which was later named, is one of 200 clams collected from a glacial shelf in Iceland. It died after freezing and was taken to a research laboratory.

Age: 405 Years

Immortal Jellyfish Could Theoretically Live Forever 

This little jellyfish is no bigger than your pink claw, but hidden inside that little body is the key to immortality. When faced with a threat, a long-immortal jellyfish can return to its larval stage and start life again.

This process, called transdifferentiation, can be triggered by starvation, injury, and other pre-existing threats. This process could theoretically allow these jellies to live forever, although verifying the age of any individual would be difficult.

Age: Infinity Years

Giant Antarctic Sponges Can Survive For Thousands of Years

Estimates for the age of this animal are surprising but, if true, it is probably the oldest living organism on the planet. Some scientists believe that giant Arctic sponges could live for thousands of years.

These sponges, which belong to the Hexactinellida group, may owe their length to their slow growth rate and the frigid waters of the deep ocean. Some estimates place the age of individuals as high as 23,000 years old, but most agree that the number is probably inaccurate.

Age: 15,000 Years

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Longest Living Vertebrate is the Greenland Shark 

These amazing living sharks are native to the icy waters of the Arctic, and a female specimen is estimated at nearly 400. Biologists have used carbon dating in proteins found in the lenses of shark eyes when the animal is old. Their discovery completely changed the view of scientists on this animal.

Age: 392 Years

Tuatara Became a Father at 111

Reptiles can only be seen in New Zealand, where one member of the species has managed to breed 11 healthy babies at the impressive age of 111. Some estimates claim that the tuataras can live upto 250, an impressive number for a small animal.

Age: 250 Years

The Oldest Living Mammals are the Bowhead Whales 

The oldest mammal in the world, bowhead whales, can live to be over 200 years old. Researchers came up with this after finding traditional stone harpists made by native Alaskans stuck to the skins of living whales. The researchers ran tests on tissue samples from multiple bowheads and found four individuals over 100 years old.

Age: 211 Years

Red Sea Urchin Rarely Show Aging Signs

A 2003 study on the lifespan of red sea urchins concluded that these amazing invertebrates can live more than 200 years without any significant signs of aging. Scientists believe that a 100-year-old female can reproduce as easily as an urchin 1/10 of that age. Two different dating methods work to determine their age, and both offer the same conclusion.

Age: Over 200 Years

(Photo : Getty Images)

Tu'i Malila, a Radiated Tortoise

Tu'i Malila lived to be one of the oldest recorded turtles of all time, having spent most of his life at the Royal Palace of Tonga. Although the turtle died in 1965 at the estimated age of 188, Tu'i Malila remains a legend to this day. 

Age: 188 Years

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