Squids Can See Without Eyes

The evolution of the eye is fascinating stuff (in a nutshell, the eye is so complex that Creationists claim that it couldn't possibly have evolved ... and scientists countered that not only did the eye evolved into being, it is so useful that it did so more than one time)

Well, add this to the mix: Margaret McFall-Ngai and colleagues at the University of Wisconsin-Madison have discovered that squids can detect light through an organ other than their eyes (and if that's not cool enough, it's done through a symbiosis with luminous bacteria!):

"Until now, scientists thought that illuminating tissues in the light organ functioned exclusively for the control of the intensity and direction of light output from the organ, with no role in light perception," says McFall-Ngai. "Now we show that the E. scolopes squid has additional light-detecting tissue that is an integral component of the light organ."

The researchers demonstrated that the squid light organ has the molecular machinery to respond to light cues. Molecular analysis showed that genes that produce key visual proteins are expressed in light-organ tissues, including genes similar to those that occur in the retina. They also showed that, as in the retina, these visual proteins respond to light, producing a physiological response.

"We found that the light organ in the squid is capable of sensing light as well as emitting and controlling the intensity of luminescence," says co-author Nansi Jo Colley, SMPH professor of ophthalmology and visual sciences and of genetics.

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