As biologists learn about life on Earth in all its diversity, and at the rate that new planets are being discovered the search for life elsewhere grows more steadily pressing. We have discovered organisms on the Earth that seem tenacious and tough almost to a fault; they thrive in the most seemingly adverse conditions imaginable, and organisms so fragile and specialized so as to exist in only the most isolated and pristine environments. With the knowledge of this great amount of diversity it is a safe bet that we will one day find organisms in other parts of the galaxy that are not indigenous to the earth. This richness of diverse life though is comprised of creatures that could only survive on the Earth, so in order to draw any strong conclusions life must be found elsewhere. Due to their relative proximity the planets of our own solar system are the best place to start this search. And finally what types of organisms could we expect to find on other planets judging from the samples on earth?.
Even with the great diversity of life on earth and new species being discovered almost daily it is unlikely that any terrestrial creatures could survive in the environments of the other planets we have discovered thus far. There is compelling evidence of flowing water on mars and that the moons of Jupiter could contain even vast frozen oceans but these are still unknowns. The other planets we have discovered outside of our solar system all appear to be gas giants similar to the gas giants of our own solar system and these planets and these planets seem like the least likely place to harbor any organisms that we know of. But we must work with the knowledge that we already have and apply the template of life to the rest of the universe since what we have learned of life on earth is all that we know however unlikely it may seem that any of the terrestrial organisms could survive off the earth.