Surprising discovery: Hogfish can See With Its Skin; what we know so far?

Ever heard about fish that can also use its skin to see like "eyes"? 

Yes, you read it right. Scientists have found out this specialised characteristics in Hogfish (Lachnolaimus maximus). A research breakthrough at UNCW and the Center for Marine Science has mentioned that this fish can actually view the color change. The hogfish is frequently observed along the Eastern Seaboard to the coast of Brazil, including the Bermuda, Bahamas, and the Gulf of Mexico.

The science of changing skin colour:

Animals do have the capability of dynamic color change, these animals are reptiles, cephalopods, amphibians, and also fish. 

These animals possess specialized skin cells named chromatophores. There are different types of chromatophores, changing color via intracellular reorganization of pigment granules, crystals, or even reflective platelets. Generally, immediately after striking the incident light, either on the underlying tissue or the exposed pigment provides the skin its colored appearance.

For the hogfish, this ability is a must for survival. This ensures proper camouflage to hide from predators like sharks, barracuda, anglers and spear fishers.  

The study:

The research team examined the morphology, physiology, and optics of dermal photoreception in hogfish and described a peculiar cellular mechanism in which chromatophore pigment activity modifies the transmitted light striking receptors in the skin. Hogfish can change colours to support their camouflaging abilities. They also have skin which can sense light. It can also be mentioned as skin vision, helping them observe their ambience.

"When dispersed, chromatophore pigment selectively absorbs the short-wavelength light required to activate the skin’s SWS1 opsin, which we localized to a morphologically specialized population of putative dermal photoreceptors," the study reported.

According to the study, light sensors are hidden beneath color-changing cells in the skin. They work like Polaroid cameras. Generally, the hogfishes clicks own pictures without using its eyes or brain, then they monitor its color-changing performance.  

Published in Nature journal, the experiment was co-authored by scientists from the Florida Institute of Technology, Florida International University, and the Air Force Research Laboratory.  

The findings:

Dynamic color change has evolved in many animals. This characteristic helps animals to deceive the predators or even warn others.

"Our findings are bigger than hogfish because they may explain why other color-changing animals (particularly vertebrates) can detect light with the skin,” said the Assistant Professor of Biology and Marine Biology Lorian Schweikert. "It also suggests the existence of specialized photoreceptors in the skin of this fish, which would be the first example of such a photoreceptor outside the central nervous system of a vertebrate animal."  

"If you had to get dressed in the morning and didn't have a mirror or couldn't bend your neck, how would you know if you dressed correctly? For the fish, this is a life-or-death question that dermal photoreception can answer," she said.

"This is an example of a feedback system, where the body monitors itself to ensure performance. Feedback systems are important in biology and technology. From studying examples of these systems, we can draw principles about how to develop smart systems that require real-time information about the precision of performance, such smart robots or self-driving cars."  

Researchers believe that observing this type of systems in fish can provide valuable information that may translate to practical implications for human beings. 

According to the scientists, this research work is crucial, as it may help finding a new path to new 'sensory feedback techniques' for devices including robotic limbs as well as self-driving cars. Researchers believe that it may help adjusting their performance without depending solely on eyesight or camera feeds.