Bacteria can 'smell' their environment, research shows

http://www.bbc.co.uk/news/science-environment-10985313

Research has shown that bacteria - among the simplest life forms on Earth - have a sense of smell.
Scientists from Newcastle University in the UK have demonstrated that a bacterium commonly found in soil can sniff and react to ammonia in the air.
It was previously thought that this "olfaction" was limited to more complex forms of life known as eukaryotes.
The finding, published in Biotechnology Journal, means that bacteria have four of the five senses that humans enjoy.

So now when I suggest some lowlife is as low as a unicellular lifeform I'm even nearer the mark.