The Eyevolution of Cephalopods

Most people have never set eyes upon the mysterious deep sea squid that inhabit our oceans. In fact, our evolutionary cousins could teach us a thing or two about our own vision.

Researchers from the Auckland Myopia Laboratory in New Zealand are looking outside the traditional short-sighted treatments for a more revolutionary approach to myopia. Teaming up with cephalopod expert Dr. Steve O’Shea, they have set their sights on Sepioteuthis australis, a species of squid found around the coast of Australia and New Zealand.

Despite their underwater habitat, squid possess remarkably similar eyes to humans. The last common ancestor of squid and humans existed around 530 million years ago during the Cambrian explosion. Since then, we have independently evolved similar ‘camera-type’ eyes that can adjust focus and brightness to suit the environment.

Optometrist and PhD candidate Philip Turnbull believes that this convergent evolution of the human and cephalopod eye may hint at some fundamental mechanism of eye growth. “Myopia is a disorder where the eye grows to long for the focusing power of the eye,” he explains. “Something has gone wrong with the growth control mechanism.”

Turnbull’s doctoral research has shown that the eye size of S. australis can be manipulated by growing them in different wavelengths of light.

“Because squid have an optically-guided growth mechanism as we do, they may be a good model for myopia,” he explains.

Despite the similar growth mechanisms, the cephalopod eye is relatively simple, with fewer photoreceptor cell layers. This means that squid may provide a simpler model in which to pinpoint where the disrupted growth control mechanism occurs.

“We’re stepping away from the vertebrate model to look at the more fundamental physiological processes,” says Dr. John Phillips, principle investigator of the Auckland Myopia Laboratory.

With up to 90% of the population suffering from myopia in some Asian countries, this is evolutionary research with a future.

But growing squid in captivity is not easily sailing. “There’s a phenomenal amount of work involved in keeping these animals alive,” says Dr. Steve O’Shea, former Director of the Earth and Oceanic Science Research Institute at the Auckland University of Technology, and the first person to grow squid in captivity. 

“Here we’ve got someone who’s conducting some serious research,” he says. “I was amazed how that might benefit humans.”