A new study found that a rare mollusk species, the Acanthopleura granulate, has hundreds of eyes layered on top of its shells. The species was successful in evading a compromise in its evolution wherein most mollusk trade-off their sight for protection.
A chiton species, the Acanthopleura granulate belongs to a class of armor-clad marine mollusk. Compared to other species whose eyes are built up of proteins, the Acanthopleura granulate's hundreds of eyes are made up of a calcium called aragonite that is found in many mollusks. Oyster's pearls are made from a combination of a protein called conchiolin and aragonite. Acanthopleura granulate's lenses and shells are both made up of aragonite.
"[The eyes] allow the animal to monitor its environment with the protective armor shell. The majority of the shell is opaque, and only the eyes are transparent," said Harvard postdoc and study author Ling Li who graduated from the Massachusetts Institute of Technology.
A study revealed that the species' eyes are similar to human eyes, whose light-focusing lenses are capable of producing real images. The study measured the mollusk's eye-focusing capabilities. The research team took out some eyes and studied them under the microscope. The researchers found that each eye is capable of producing a small pixelated image. The retinas are also small and can only host limited receptors. The mollusk species don't need a super sharp focus to see an incoming predator. When in danger, they hide between rocks until there is no more threat.
The researchers found that the species have developed several defense strategies. The rare mollusks can grow up to 1,000 eyes on their armor which form several clusters, enabling them to see at various points. They are also capable of growing more eyes throughout their lifetime, effectively replacing any eyes that have been compromised. Any damage done to their shells do not penetrate deeply due to its viscosity and resistance.
The scientists hope that their rare find and analysis can lead to future material applications such as military gadgetry that can operate in harsh conditions. Replicating one of nature's best defense mechanisms could lead to the production of heavy-duty eye wear that can protect soldiers in duty.
The rare finding was published in the journal Science on Nov. 20.
