Researchers have found new forms of life that are totally unkown in underwater caves in the Bahamas called "blue holes." These caves can provide clues on how life evolved not only on Earth but possibly on alien worlds, researchers said.

The researchers, led by Tom Iliffe, a marine biologist at Texas A&M University at Galveston, examined three inland blue holes in the Bahamas and discovered that layers of bacteria exist in all of them, although the microbes are significantly in one sinkhole are significantly different from the others.

The findings that each cave has different conditions from the others and thus a different forms of life will help scientists analyze the diverse routes life might have taken on Earth, according to researchers.

"These bacterial forms of life may be similar to microbes that existed on early Earth and thus provide a glimpse of how life evolved on this planet," Iliffe explained. "These caves are natural laboratories where we can study life existing under conditions analogous to what was present many millions of years ago."

Iliffe and his colleagues said these findings might also shed light on how life might have developed on distant planets and moons.

The researchers noted that tens of thousands of underwater caves are scattered around the world, but less than 5 percent of these have ever been explored and scientifically investigated.

"We know more about the far side of the moon than we do about these caves right here on Earth," Iliffe said. "There is no telling what remains to be discovered in the many thousands of caves that no one has ever entered. If life exists elsewhere in our solar system, it most likely would be found in water-filled subterranean environments, perhaps equivalent to those we are studying in the Bahamas."

Other places have turned out to be habitats for life, including some which may be considered as strange or seeming inhabitable places on the planet. The website ouramazingplanet.com listed the strangest places that is home to life. Among them are:

• Bubbling lakes of hot tar, which seem unlike to host living things, apparently teem with microbial life. In Pitch Lake, on the Caribbean island of Trinidad the world's largest naturally occurring asphalt lake, each gram of sticky black goo can harbor up to 10 million microbes.

• Radioactive wastes can be home to some species of bacteria like the bacteria Deinococcus radiodurans which can take up to 5,000 grays with no visible effect, and can even withstand up to 15,000 grays, earning it the title of "world's toughest bacterium" in the Guinness Book of World Records.

• Boiling water which can kill humans is home to a dazzling array of life. Underwater hot springs in the Pacific Ocean teem with tubeworms and giant clams, while the Atlantic variety is typically home to eyeless shrimp and other extreme residents.

• The Dead Sea is one of the saltiest bodies of water in the world, making it too harsh for most life to thrive there. But salt-loving or "halophile" microbes can thrive in this water body.

• Frozen ice, like lakes buried under ice, has been home to microbes. In the oldest known ice on Earth in Antarctica, scientists revived microbes that had been frozen for millions of years.