A new discovery by QBI researchers published in the eminent journal Science, has shattered illusions that despite having eyes able to process more colour channels than humans, the mantis shrimp does not necessarily have better colour vision.
Lead researcher, Ms Hanne Thoen from the Marshall Laboratory, found that Haptosquilla trispinosa (mantis shrimp), which process 12 colour channels compared to three in humans, actually perform worse in differentiating between colours.
“Theoretically, mantis shrimp should be far better at distinguishing colours than we are,” Ms Thoen said.
“Human brains – and all other animals including birds, monkeys, frogs and fish – determine the colours of objects by comparing the relative excitation of inputs. For instance, in humans this is red, green and blue,” she said.
“The critical finding is that mantis shrimp do not, and this means their way of encoding colour is different to all other animals known.”
A number of tests were conducted, including training the animals to respond to certain colours and using a two-way choice test with food as a reward.
By receiving food when choosing one particular colour and not any other, the animals quickly learned which choice to make and also revealed how they encode colour.
“We tested their ability to discriminate between colours that differ a lot – such as red and blue, and then changed to colours that got closer and closer together along the spectrum – red-green, red-yellow, red-orange – and noted when they started to make mistakes,” Ms Thoen said.
“Results were also compared to a number of other animals including humans, bees, fish and butterflies, and although theoretically they should be better than all of them, they are far worse.”
The findings demonstrate how evolution pushed the design of the nervous system towards a simple arrangement, rather than trying to fully interpret all of the information from a very complex colour vision at the retinal level.
The importance and implications of the finding is highlighted by Science running a commentary on the article.
“We have no doubt that this new discovery will stimulate and inspire the advancement of new and innovative technologies within the applied sciences,” Ms Thoen said.
“Modern cameras struggle with the amount of data they take in due to increased pixel numbers; maybe there is a more efficient way and the bio-inspiration provided by stomatopods could be the answer.”