Sometimes it’s hard to believe that we take scientists seriously, especially when they do some seemingly wacky experiments. One such experiment that has us scratching our heads is a recent study done to test the eyesight of cuttlefish.
The scientists put tiny 3D glasses on the cephalopod to test how the animals’ 3D vision works.
According to Science Alert, despite having the strangest eyes in the animal kingdom, the cuttlefish 3D vision works a lot like ours.
Warning: Includes cuttlefish with 3-D glasses GIF pic.twitter.com/sa9drCN01T
— UMN CBS (@umncbs) January 9, 2020
Cuttlefish eyes have one type of photoreceptor, which should mean they can only see in black-and-white; but they have a unique, W-shaped pupil that may allow them to perceive colours in a completely different way from vertebrates.
“This study takes us a step further toward understanding how different nervous systems have evolved to tackle the same problem,” neuroscientist Rachael Feord of the University of Cambridge in the UK told Science Alert.
While human eyes focus by changing lens shape, cuttlefish lenses actually change position. Their eyes also face opposite directions, giving them full 360-degree vision.
The scientists superglued a small velcro patch between the eyes of 14 cuttlefish, making it possible to attach the 3D glasses. The cuttlefish were then trained to attack prey with their tentacles.
The “prey” were images on a computer screen of two shrimp displayed in front of the tank. Each shrimp was a different colour to make it appear through the glasses that one was in front of the screen while the other was behind it.
To test if the cuttlefish was using stereopsis to judge the distance to moving prey, they would strike shrimp in the offset position.
This is what the cuttlefish did, establishing that they use stereopsis when hunting. This makes them only the second known invertebrate to use stereopsis to perceive distance.
Image: NewScientist/ Twitter