It suggests that humpback whales are nearsighted and often collide with objects.

Recent studies indicate that humpback whales often collide with objects due to their surprisingly limited vision.

This gentle giant struggles to discern fine details until it is quite close, which may explain the unfortunate incidents of these animals becoming entangled in fishing nets or crashing into small vessels.

To gain insights into how humpback whales perceive their surroundings, a group of marine biologists examined the left eye of a deceased whale after it had been stranded.

In the study, the researchers found that the rear part of the whale’s eye was considerably thicker than anticipated. This suggests that the distance from the retina to the lens (the eye’s focal length) is much shorter than expected.

A shorter focal length implies that the whale’s capability to resolve finer details is significantly lower than previously believed.

This theory was further supported by the team’s count of the neurons responsible for transmitting visual information to the brain, which revealed a stark contrast.

While a typical human eye has around 40,000 retinal ganglion cells per square millimeter, humpback whales possess only about 180.

This level of poor vision typically doesn’t hinder whales, but Professor Lori Schweikert from the University of North Carolina Wilmington noted in BBC Science Focus.

“Apart from prey, humans, and some bird species, many animals possess relatively low vision,” says Schweikert.

“However, their visual capabilities are often adequate for their survival needs in their natural habitats. For humpback whales, they may primarily need to recognize large shapes, such as a big school of prey or other swimming whales.”

Humpbacks can identify large objects from a distance, but finer details come into focus only when they are about 45-60 meters away, or within 3-4 lengths of their bodies.

This means whales may struggle to see thin strands of fishing nets.

“At close range, they should be able to identify such structures,” Schweikert adds.

About our experts

Professor Lori Schweicart serves as an assistant professor of biology and marine biology at the University of North Carolina Wilmington. Her research centers on the physiological mechanisms involved in light reception within marine settings.

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