Shark Vision: World is Black and White to Ocean’s Top Predators
A new study by researchers from the University of Western Australia (UWA) and the University of Queensland has confirmed that most sharks are completely color-blind.
A Spotted Wobbegong shark (Orectolobus maculatus) near Shelly Beach, Sydney, Australia. Photo credit: Richard Ling (richard@research.canon.com.au)
The researchers compared visual adaptations of two species of wobbegong (carpet) sharks, Orectolobus maculatus and Orectolobus ornatus.
Carpet sharks
- live in relatively shallow waters
- are bottom-dwellers
- are well camouflaged to match the ocean floor
- are not considered dangerous to humans
- hunt mostly at night
- are ambush predators (sit and wait for prey to swim by, then attack)
A previous PhD study by Dr. Susan Theiss concluded that carpet sharks only have one class of cone photoreceptors. Cone photoreceptors are the ones responsible for color vision and function best in bright light. However, color vision comes from a combination of cones; if only one type of cone is present, the animal cannot see in color.
In the latest study, the researchers found that the sharks only had one cone pigment gene.
“The results from this study will help us not only to understand the evolutionary selection pressures operating on shark vision, but may also provide to key to how we can influence their behavior,” explained lead researcher Nathan Hart, assistant professor from the UWA Oceans Institute and School of Animal Biology.
“Sharks are highly visual animals, but the world they see lacks color and will appear as shades of grey,” he said. ”It may be possible to use this knowledge to change the way a shark reacts to certain objects.”
“For example, it may be possible to design long-line fishing lures that are less attractive to sharks to reduce the incidence of shark bycatch. It may also lead to better design of equipment such as wetsuits and surfboards that reduce the risk of shark attack,” Hart said.
To learn more:
- Read the full press release from UWA
- Find the full publication from The Royal Society’s Biology Letters here: Cone monochromacy and visual pigment spectral tuning in wobbegong sharks
Copyright © 2012 by Marine Science Today, a publication of Marine Science Today LLC.
