Animal Vision: Giant And Colossal Squid Eyes

The words attributed to the largest of squid species in the giant and colossal manifestations suggest that their bodily features are likely to be on the large side, with an interesting theory on how their eyes have developed and evolved to help protect the oversized squids from becoming an easy target for lurking predators in the depths of the ocean.

All The Better to See You With

The giant squid’s eyes are roughly the size of a basketball or football, thought to be two to three times the size of any other living animal on the planet, and is even out of proportion with the vast thirteen and fifteen metre body lengths respectively when fully stretched out. They can be found in the darkened depths of the deep oceans of which they are widely distributed across areas such as the North Atlantic Ocean and oceanic islands of Azores and Madeira.

Scientists have often wondered just why the large squids have evolved to have such large eye features, with the general consensus being that they help spot sperm whales, their most frightening of predators. Colossal squids in particular are known to possess weapons such as large beaks and barbed swiveling hooks to help do battle with a sperm whale, although the fact that the stomachs of the whales are often lined with squid beaks suggest that they often come off second best, with squid forming a majority of a sperm whale’s daily diet.  

What Scientists Have Found

Scientific studies including those lead by Dan Nilsson of Lund University, Sweden, have seen dissected colossal squids several years ago in New Zealand in a bid to determine exactly how large eyes would give the squids an advantage in their marine habitat. The harder parts of the lens alone were found to be bigger than the entire human eye, so it could be suggested that their vision would likely be superior in many ways to ours.

Even though squids are not the largest animals to exist, the fact that their eye size sees a significant jump from any related species and sub groups suggests that they have evolved for a particular reason. It is widely known that whales can use advanced sonar similar to that of a submarine radar to hone into an unwitting squid’s location, so the only method the squid can rely on to avoid confrontation is the ability to adapt their vision to see the predators from a significant distance.
Various tests have used a combination of differing eye shapes and mathematical models to determine sight at various water depths up to 1km. It is believed that only one benefit is gained from developing larger eyes for an animal such as a squid, which is the increased ability to view very large moving objects such as a whale, seeing the increased lens size allow for greater detection of light sources from organisms in poorly lit environments.

Evasive Action

These findings suggest that a giant or colossal squid would be given a warning distance of up to 120m, providing enough time to attempt to hide and avoid becoming the whale’s next meal, highlighting an impressive feat of forced evolutionary bodily function.

Jamie blogs about animal eyesight for leading prescription glasses retaielr Direct Sight.