Armored mollusk sees with hundreds of eyes, a rare find for biologists looking to understand how some evolutionary trade-offs occurred with the marine organisms.
Some mollusks have evolved to develop armored shells responding to two needs: it both protects them while hosting ‘eyes’ allowing them to sense the surrounding environment. The armored mollusk in case is known as the Acanthopleura granulata, a chiton which has actual eyes in its hard shell. The living tissue acts a mineral-based lense and allows the Acanthopleura granulata to form real images, albeit less detailed than we see for instance.
The researchers studying the armored mollusk hope their findings could lead to further engineering innovations. A new lightweight armor also sporting sensory capabilities is one example of innovations stemming from these biological findings.
To understand the role of the eyes in the armored shell of the Acanthopleura granulata chiton, Ling Li, lead researcher and Harvard postdoc and her team took out of few of the eyes of an Acanthopleura granulata chiton and conducted optical experiments.
These microscopic lenses allow the armored mollusk to really see and monitor its environment. In doing so, it is able to respond rapidly to any approaching threat from predators. When such a threat is in its vicinity, the eyes withdraw and clamp back in the armored shell. The research team observed an evolutionary trade-off. The armored mollusk sees with hundreds of eyes. However, as the size and complexity of the microscopic lenses increases, the armored shell performs less well in protecting the mollusk in those specific areas.
The eyes of the Acanthopleura granulata chiton are composed of aragonite, as its its armored shell. According to Ling Li, also a graduate of MIT, the shell of the mollusk is generally opaque. The cavities where the eyes are found are transparent. The eyes of the armored mollusk have the capability to focus and form images, albeit smaller and more pixelated than they are formed with humans.
Some of the Acanthopleura granulata specimens may develop as many as 1,000 eyes tucked in the armored shell. With such a great number of eyes, they are typically organized in several ‘seeing’ clusters acting as surveillance cameras all around the mollusk.
If it does happen that the transparent and exposed spaces in the mollusk’s armored shell are attacked and damaged, the Acanthopleura granulata has the capacity to grow new eyes to replace the lost ones.
Photo Credits: Wikimedia