> When the organ is full of these bacteria, the bacteria glow and therefore stop the shadow of the octopi.
It seems weird because the animal itself would be a lot more visible.
This wikipedia article [1] about firefly squid says that the animal uses it's ability to match the brightness and colour of its underside to the light coming from the surface, making it difficult for predators to detect it from below
Here is the species that I learned about. [1] As I mentioned in another comment, I learned about this in a microbiology course so the focus was on the Vibrio species of bacteria, not as much about the octopus.
It seems weird because the animal itself would be a lot more visible.
This wikipedia article [1] about firefly squid says that the animal uses it's ability to match the brightness and colour of its underside to the light coming from the surface, making it difficult for predators to detect it from below
Is that it?
[1] https://en.wikipedia.org/wiki/Firefly_squid