Squid Light-Organ Symbiosis: Quorum-Sensing Switch

The Hawaiian bobtail squid keeps a monoculture of the bioluminescent bacterium Vibrio fischeri inside a dedicated light organ, and the two partners run one of biology's cleanest quorum-sensing circuits: each bacterium leaks a small autoinducer molecule, the crypt's near-closed geometry lets that signal accumulate with cell density, and once it crosses a threshold the entire population flips on its luciferase genes in near-synchrony. This simulation renders that crypt as a population of instanced bacteria that colonize the space, tracks the logistic growth of the population and the autoinducer concentration it produces, and drives each cell's light-emitting state through the same Hill-function switch measured in the real LuxI/LuxR system — including the dawn venting the squid uses every morning to reset the colony.