Disruptive eye mask

The eye has a distinctive shape and dark coloration dictated by its function, and it is housed in the vulnerable head, making it a natural target for predators.

Disruptive eye masks are seen on a variety of animals, both invertebrates such as grasshoppers and vertebrates, including fish, frogs, birds and snakes.

Eye masks were first noticed by the American artist Abbott Handerson Thayer in 1909, and analysed extensively by the zoologist Hugh Cott in 1940.

He recorded that "what appear to be markings of similar significance" are found in mammals such as gemsbok, sable antelope, Grant's gazelle and vizcacha.

He found that fast-swimming species had longitudinal lines and long bodies; deep-bodied fish had vertical bars and the ability to turn abruptly.

[12] In 2013, Karin Kjernsmo and Sami Merilaita showed using artificial prey and predatory fish (three-spined sticklebacks) that such eyespots diverted predators' attacks from the vulnerable head.

Gaboon viper , its eye concealed by a disruptive mask
Early investigators Abbott Handerson Thayer and Hugh Cott noted that active juvenile birds like this little ringed plover chick have boldly disruptive patterns that camouflage the eye.
Cott used this diagram to illustrate "the inherent conspicuousness of an eye-spot", and hence to justify the need for a disruptive eye mask. [ 1 ]