Hawaiian Bobtail

• In a light organ in its mantle it houses a single bacterium, Vibrio fischeri, whose light it uses for counter-illumination: it matches the moonlight coming from above and erases its own silhouette from the view of predators below.
• It is born without the bacterium. Each generation recruits it from seawater within hours, even though Vibrio fischeri makes up less than 0.1% of the bacteria present. And if it is absent, no other bacterium will colonise the organ.
• Every dawn it expels most of its bacteria and those left multiply again through the day, in a daily cycle.
• It can regulate how much light its symbionts produce according to how much reaches it from the surface.
• This partnership is one of the most important model systems in biology: bacterial quorum sensing was discovered with it, and it has been used to study how a microbiome establishes itself, how bacteria drive animal development and how pathogenicity evolves.

Habitat and environment

Shallow sandy bottoms of the Hawaiian Islands, mostly seagrass meadows and sand flats; it buries itself by day and comes out to hunt at night

Sources consulted: https://es.wikipedia.org/wiki/Euprymna_scolopes

The pins mark the parks and dive sites where its presence is documented.