Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How can a colorblind animal change its colors to blend into the background?

17.05.2011
Team from MBL, West Point uses new imaging technology to 'see' camouflaged marine animals in the eyes of their predators

U.S. MILITARY ACADEMY, WEST POINT, N.Y.—How could a colorblind animal know how to change its skin color to blend into its surroundings? And what will the animal's predator "see," looking at its prey before and after it hides?

These provocative questions are addressed in article published today by a collaborative team from the Marine Biological Laboratory (MBL) in Woods Hole, Mass., and the U.S. Military Academy in West Point, N.Y. The article, "Hyperspectral imaging of cuttlefish camouflage indicates good color match in the eyes of fish predators," appears in Proceedings of the National Academy of Sciences (PNAS).

"What makes camouflage effective? The answer is that it's an opinion, and that opinion completely depends on who is being asked. Our work presented in this paper takes the field a step closer to quantifying camouflage effectiveness," says J. Kenneth Wickiser, Asst. Prof. in the Department of Chemistry and Life Science at the U.S. Military Academy in West Point.

Understanding the principles of camouflage is not only important in biology, but also provides insights into architecture, advertisement, and defense applications.

For this study, the team studied camouflage in the marine animals known as coleoid cephalopods (octopus, squid, and cuttlefish). Camouflage is the primary defense in these animals and their rapidly adaptable body patterning system is among the most sophisticated in the animal kingdom. The expression of camouflage body patterns in cuttlefish is a visually driven behavior. Previous studies have shown that certain background variables—such as brightness, contrast, edge and size of objects, etc.—are essential for eliciting camouflaged body patterns. However, cephalopod eyes lack color perception, thus the vexing question of how they achieve effective camouflage while being colorblind still remains.

Moreover, camouflage studies suffer from the inability to assess the effectiveness of camouflage in the visual space of predators; in short, it is difficult to determine whether a predator actually visually picks out the prey from the background environment. Knowledge of the visual capabilities of many predators is surprisingly lacking. Thus, the team asked, how does a colorblind animal change its color to blend into its surroundings, how do predators actually "see" their prey?

"To tackle this incredibly difficult problem, we put together a team with Chuan-Chin Chiao as a vision expert, Roger Hanlon and his scientists at the MBL as world leaders in cuttlefish and camouflage biology, and combined it with our expertise in hyperspectral imagery analysis at West Point," says Wickiser.

The team exploited a new imaging technology (HyperSpectral Imaging, HSI) to more accurately measure color match between animal and background, and to enable them to model camouflage in the eyes of predators. HSI employs a camera that captures not just 3 narrow windows (Red, Green, Blue – RGB) like human eyes or typical digital cameras do rather it captures the entire spectrum using 540 windows. In essence, HSI offers the opportunity to "see" things that humans, and many predators, cannot because of the limitations on our eyes. Because of the wealth of information HSI images provide, the scientists could extract a small amount of that data and compile an image from the perspective of a predator.

Importantly, modeling color vision of potential di- and tri-chromatic (RG or RGB capable) fish predators of cuttlefish corroborated the spectral match analysis and revealed that much of the contrast information (which allows a predator to "pick out" a cuttlefish from the background environment) resides in the brightness (luminance) rather than in the color (chromatic) aspect of the reflected light. What this means is that cuttlefish camouflage strategies take away a tool from predators in their ability to pick out their prey from the background and instead leave them with only brightness as a method for prey identification.

These findings (i) indicate the strong potential of HSI technology to evaluate camouflage body patterns simultaneously in the spatial and spectral domains, (ii) provide supporting evidence that cuttlefish can produce color-coordinated camouflage on natural substrates despite lacking color vision, and that (iii) the color aspect of cuttlefish camouflage is highly effective against fish predators. This is the first time that color matching in camouflaged animals has been visualized more realistically through the eyes of their potential predators.

"So much is unknown about how predators actually see their prey. Using hyperspectral imagery tools is a huge advance in getting us the information we need to model predator vision," says Wickiser. "We hope our work takes us one step closer to understanding how a colorblind animal adopts near-perfect camouflage in a variety of backgrounds."

The color-changing abilities of cephalopods have been appreciated since Aristotle's time. Although this topic has received much attention in the past, no quantitative assessment has been made to examine the color match between animal and background. Applying hyperspectral imaging system and modeling the predator's visual system adds a new dimension to quantifying animal camouflage in the eyes of the beholders. The team's findings provide strong support that cuttlefish are capable of hiding in plain sight of their visual predators. Furthermore, this approach may prove to be tranformational in the way that color is quantified in sensory studies of camouflage and signaling in the natural world.

Citation:

Chiao, C-C, Wickiser, J.K., Allen, J.J., Genter, B., and Hanlon, R.T. Hyperspectral imaging of cuttlefish camouflage indicates good color match in the eyes of fish predators. PNAS Early Edition, week of May 16, 2011.

About West Point

The U.S. Military Academy is a four-year co-educational federal undergraduate liberal arts college located 50 miles north of New York City. Founded in 1802 as America's first college of engineering, it consistently ranks as one of the top colleges in the nation. A pre-eminent leader development institution, its mission remains constant - to educate, train and inspire cadets for careers of professional service to the Army and the nation. For more information go to www.westpoint.edu.

The Marine Biological Laboratory (MBL) is dedicated to scientific discovery and improving the human condition through research and education in biology, biomedicine, and environmental science. Founded in 1888 in Woods Hole, Massachusetts, the MBL is an independent, nonprofit corporation.

Jim Fox | EurekAlert!
Further information:
http://www.usma.edu
http://www.westpoint.edu

More articles from Life Sciences:

nachricht Enzyme with surprising dual function
24.01.2018 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht Flexibility and arrangement - the interaction of ribonucleic acid and water
24.01.2018 | Forschungsverbund Berlin e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Optical Nanoscope Allows Imaging of Quantum Dots

Physicists have developed a technique based on optical microscopy that can be used to create images of atoms on the nanoscale. In particular, the new method allows the imaging of quantum dots in a semiconductor chip. Together with colleagues from the University of Bochum, scientists from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute reported the findings in the journal Nature Photonics.

Microscopes allow us to see structures that are otherwise invisible to the human eye. However, conventional optical microscopes cannot be used to image...

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Physicists have learned to change the wavelength of Tamm plasmons

24.01.2018 | Physics and Astronomy

When the eyes move, the eardrums move, too

24.01.2018 | Health and Medicine

Deaf children learn words faster than hearing children

24.01.2018 | Health and Medicine

VideoLinks Science & Research
Overview of more VideoLinks >>>