Squid Shops K-Mart

The following extract is from the April 2003 edition of Wired magazine. I didn't get permission to reprint it here, but oh well, sucks to be them (not really).

I post this to remind you of the various different forms of life we have just on this one planet and make you question what in evolution caused this particular species to develop such a delicate trait. -the lock

Section from "The Bacteria Whisper"
by Steve Silberman, Wired

The bobtail squid lives in the knee-deep coastal shallows in Hawaii, burying itself in the sand during the day and emerging to hunt after dark. On moonlit nights, the squid's shadow on the sand should make it visible to predators, but it possesses a "light organ" that shines with a blue glow, perfectly matching the amount of light shining down through the water.

The secret of the squid's ability to simulate moonlight is a densely packed community of luminescent bacteria called Vibrio fischeri. Minutes after birth, a squid begins circulating seawater through a hollow chamber in its body. The water contains millions of species of microbes, but cilia in the squid's light organ expel all but the V. fischeri cells. Fed with oxygen and amino acids, they multiply and begin to emit light. Sensors on the squid's upper surface detect the amount of illumination in the night sky, and the squid adjusts an irislike opening in its body until its shadow on the sand disappears. Each morning, the squid flushes out most of its cache of glowing vibrios, leaving enough cells to start the cycle anew.