Invertebrates
Cockeyed Squid
Histioteuthis heteropsis · also called strawberry squid
Hanging tilted in the water with one large, bulging eye fixed upward and one smaller eye watching below, a cockeyed squid uses two completely different visual strategies at once to hunt in the layered darkness of the deep sea.
Overview
The cockeyed squid, Histioteuthis heteropsis, is an asymmetrically eyed cephalopod native to mesopelagic and bathypelagic ocean habitat recorded across multiple ocean basins worldwide. Its strikingly uneven pair of eyes, each specialised for a different visual task, membership in the sparkling jewel squid family, and tilted resting posture make it one of the more visually distinctive cephalopods found anywhere in the deep sea.
Two eyes, two completely different jobs
Rather than using a matched pair of eyes the way most animals do, the cockeyed squid has split the work between them, dedicating one enlarged eye to scanning for silhouettes above and a smaller eye to watching for bioluminescent flashes below, a division of labour unlike almost any other animal.
Status
Least Concern, though population trends remain largely unknown given the difficulty of surveying deep-sea habitat.
Cockeyed Squid: common questions
Why does the cockeyed squid have two different-sized eyes?
The larger, upward-facing eye is thought to scan for the silhouettes of prey against faint light from above, while the smaller, downward-facing eye instead watches for flashes of bioluminescence produced by other deep-sea animals below, giving the squid two complementary ways of detecting prey.
Why does the cockeyed squid hang at an angle in the water?
This species is often observed hanging in the water at a tilted angle, positioning its larger eye upward and its smaller eye downward, allowing each differently specialised eye to make the most of its particular role.
What is a jewel squid?
This species belongs to a family known as the jewel squids, named for the sparkling appearance of their many light-producing photophores when caught in artificial light during deep-sea observation.
How does the cockeyed squid use its photophores?
This species is covered in light-producing photophores across the underside of its body, used for counter-illumination camouflage that helps mask its silhouette from predators looking upward from below.