Florida Atlantic University researcher and member of the Center for Ocean Exploration and Deep-Sea Research at Harbor Branch Oceanographic Institute, Dr. Tamara Frank, was part of an international research team that discovered the first vertebrate with eyes that use mirrors rather than lenses to focus light.
Results from this research have been published in the January issue of Current Biology. The article, titled “A Novel Vertebrate Eye Using Both Refractive and Reflective Optics,” describes the unusual eyes of the spookfish, Dolichopteryx longipes. These eyes are tubular, which are similar in structure to the eyes of many other fish that swim in the ocean’s twilight zone where the background light field is very dim.
“What makes this animal so unusual is that each eye is divided into two parts, one pointing upwards and one pointing downwards, making it look like it has four eyes, and four-eyed fish don’t exist,” said Frank.
In the few other species of deep-sea fish that possess split eyes, the upper eye has a lens, like in the spookfish, for focusing light. However, at these depths, there is so little upwelling light that a lens would attenuate light too much in its efforts to focus the light for the lower eye. Therefore, in other fish, the lower eye doesn’t have a lens, resulting in a blurred image. The spookfish however, manages to focus light in the lower eye without using a lens. Light enters the lower portion of the eye and hits a mirror composed of stacks of crystals. The stacks sit roughly parallel to one another, but their angle changes over the surface of the mirror, giving it an overall concave shape. A computer simulation by research team member Dr. Julian Partridge, Bristol University, United Kingdom, showed that orientation of the plates within the mirror's curved surface is perfect for focusing reflected light onto the fish's retina. This is the first time that this type of focusing mechanism has ever been found in a vertebrate.
Many deep-sea or night active animals (including dogs and cats) use mirrors behind the retina to make their eyes more sensitive to light, hence why their eyes seem to glow when a light shines on them. It has been estimated that this reflecting layer, the tapetum, doubles the sensitivity of the eyes that possess them. With these animals, the mirror sits behind the eye and cannot focus light. In the spookfish, the mirror sits in front of the retina and serves to focus light, providing an image that’s much brighter than a lens could produce.
“While this species was first described 120 years ago, the few specimens that have been collected in the past were dead and quite mangled, so very little could be discerned about their visual systems,” said Frank.
The expedition, led by Dr. Hans-Joachim Wagner from Tübingen University in Germany on the German research vessel Sonne, utilized Frank’s “Tucker Trawl,” built by Harbor Branch’s engineering division. The opening/closing net has a special temperature-insulated collecting vessel at the end that can be closed at depth. This feature enabled the scientists to secure the first-ever living specimen of this very rare fish from a depth of 700 meters over the Tonga Trench off Samoa. Pictures of the live animal immediately revealed that there was something unusual about the eye. Once back on land, the scientists examined the structure of the eye and discovered its unique properties.About Harbor Branch:
Gisele Galoustian | Newswise Science News
Bolstering fat cells offers potential new leukemia treatment
17.10.2017 | McMaster University
Ocean atmosphere rife with microbes
17.10.2017 | King Abdullah University of Science & Technology (KAUST)
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
17.10.2017 | Life Sciences
17.10.2017 | Life Sciences
17.10.2017 | Earth Sciences