QUORUM SENSING
Earth has always been a planet run by and for bacteria. We are only just beginning to have the first idea about the eerie sophistication of so much of what they do, such as bacterial communication systems.
Each bioluminescent vibrio bacteria produces a chemical signal called an autoinducer. As its host, the Hawaiian bobtail squid jams ever more of these bacteria into its light organ, the vibrio reach a critical concentration that triggers the enzyme luciferase to switch on vibrio’s light-producing lux genes. This is called Quorum Sensing because the bioluminescent bacteria only switch on their light when they sense they are in a quorum. This stops them wasting energy, because an individual vibrio can’t produce much light, but beyond a critical threshold they glow like UV.
For vibrio, emitting light is something they only do in company. For them, as for us, there are some things you only ever do when you are with a bunch of mates.
...Although, that said, I confess it came as some surprise to learn from his diaries that when the solitary Wordsworth, finding himself alone on Westminster Bridge, composed the immortal lines:
The river glideth at his own sweet will:
Dear God! the very houses seem asleep;
And all that mighty heart is lying still!
He was actually up the top of a lamppost wearing a traffic cone on his head.