Wow. There’s a place called Mono Lake, in California. It’s an ancient saline lake (3 times as salty as the ocean) with a pH of about 10, making it rather alkaline. It is also loaded with arsenic. Though you and I might think that would make it quite inhospitable to life, it supports a very diverse and interesting ecosystem, including brine shrimp and algae.
Most excitingly, NASA researchers recently discovered a bacterium living in the lake, that actually uses arsenic instead of phosphorus as the backbone for its DNA molecules. Up until now, phosphorus (along with oxygen, carbon, hydrogen, sulphur and nitrogen) was thought of as one of the building blocks of life.
What does that mean for the possibility of life on Earth? And what about life on other planets? Should we pump lots of money into searching for it? And if organisms can adapt so well to their surroundings, perhaps we shouldn’t worry quite so much about climate change and damaging habitats, as surely, life will always prevail? Well I’m playing devil’s advocate here, but you could do the same in a classroom discussion!