Sunlight is only seeable in the top one thousand meter of the ocean , and the pressure of living in the dim , dingy deep has led to some bizarre adaptations . A tiny half-pint - similar critter calledParaphronima gracilislives in intermediate , or mesopelagic , habitat — depths that are totally grim to our eye . And fit in tofindingspublished inCurrent Biologythis week , each of their giant oculus has 12 distinct retinas , the light - sensitive stratum of the eyeball .
brute live in mesopelagic surroundings face a incessant struggle : Be able to perceive dim sparkle and bioluminescent sources , but also remain invisible to predators . These struggles generate counterpoint selection pressures on the eyes of these inhabitants . Hyperiid amphipod are a family of small crustaceans with at least 10 different eye configurations , ranging from abstruse - ocean species with no eyes to mesopelagic ones with four blown-up eyes .
A team guide byJamie Baldwin Fergus of the Smithsonian Institutioncollected the hyperiid amphipodP. gracilison dark trawls off the roentgen / V Western Flyer in the Monterey Submarine Canyon between depths of 200 and 500 meters . These transparent crustaceans have a pair of heavy compound eye — about 45 percentage of their whole body — and they swim with their eye positioned up to run for prey swim above .
Each of their chemical compound eye , the researchers found , have a prominent up - looking lot and a smaller lateral - wait portion . The strangest part is that the upward - looking portions have a row of ommatidia ( the facets that make up a chemical compound centre ) that ends in 12 noncontinuous retinas . In the image above , the carmine orange coloration is from screen pigment locate within and around the “ retinula prison cell ” contributing to each of the ommatidia .
“ We have never seen the retina split up this way in any other arthropod eye , not in insects , not in crustacean or other animals with a compound eye,”Baldwin Fergus say in Smithsonian Science . In most colonial eyes , the retina is a single uninterrupted sheet . “ This centre plan has not been described antecedently and its function is unsung , ” she adds . They think that each retina captures an image that ’s then passed onto the brain , Science reports , which integrates the 12 images to increase brightness and demarcation sensitivity . It belike confer an advantage under the changing light conditions of those wispy , monochromatic deepness .
