Hawaiian bobtail squid are nocturnal predators, remaining buried under the sand during the day and coming out to hunt for shrimp at night near coral reefs. The squid have a light organ on their underside that houses a colony of Vibrio fischeri. V. fischeri is a relatively rare glowing bacteria making up less than 0.1% of the seawater bacterial community. The squid uses this bacterial bioluminescence in a form of camouflage called counter-illumination. The squid are able to mask their silhouette by matching moonlight and starlight, thus hiding from predators swimming below. The light organ is attached to the ink sac and it can use this ink like a type of shutter to control the amount of light. This likely helps the squid adjust to variable light conditions, for example cloudy nights or a full vs. new moon.
This image depicts three stages during Hawaiian bobtail development. The Hawaiian bobtail squid lay their eggs in clutches on the sea floor, where they take approximately three weeks to develop. Once the squid hatches, cilia (hair-like structures) assist in bringing V. fischeri in the seawater to pores at the base of the light organ. These pores lead to inner crypts, where only V. fischeri can enter and colonize. This process occurs within hours of the squid hatching.
Approximate height of image is 1.5 centimeters.
