If you're a seafood lover, chances are you've tasted scallops (family Pectinidae). 𝘊𝘩𝘭𝘢𝘮𝘺𝘴 𝘯𝘰𝘣𝘪𝘭𝘪𝘴 (Reeve, 1852) Chlamys farreri is a common species, also known as “noble scallop” or “South Australian golden scallop”. Although it is named "Golden Shell", the color of its shell actually ranges from orange, yellow to brown and purple. It is naturally distributed in the waters of Southeast Asia, is one of the most consumed edible species in the region, and is also farmed in southern China. We eat the fleshy, juicy and delicious adductor muscle, which is used to open and close the shell, which is actually the swimming motion of the noble scallop! Yet even avid seafood lovers may not be familiar with this mollusk’s fascinating biology. The hard, ridged shells form two lids that protect the entire mollusk, including adductor muscles, gills for underwater breathing, heart, gonads (they can switch genders and even become hermaphrodites, with both male and female reproductive organs), mouth and the entire digestive tract - which is very important for filter feeders that eat microalgae. And the most interesting thing is that they have many, many eyes! Different species have different numbers, with some species having as many as 200 (you can try to count the eyes of the ornate scallop in this picture). The eyes, along with tiny tentacles or cilia, are arranged on the scallop's mantle, the outermost edge of the shell that you can see when it is partially open and protrudes from the shell.
It's strange enough to think that the same parts of scallops that we can see are also visible to them - not to mention that the structure of their eyes is so different from most eyes in nature that it's fascinating. Of course, they are very different from us. In the human eye, when light enters the pupil, a powerful lens focuses the light precisely onto the retina at the back of the eye. In scallops (and some crustaceans and deep-sea fish), light travels through a thin lens to the back of the eye, where a concave lens (like a telescope)The lens and mirror reflect light back onto two different retinas, which are located back to back between the lens and the mirror. It may seem very complicated at first glance, but in short, the scallop eye's mirror is made of crystals precisely arranged, like a mosaic, to reflect the correct wavelength of light onto the correct retina. One retina is used for peripheral vision, while the other provides central vision. All retinal information is transmitted through the visual nerve to the same information center, which integrates environmental information.
Since we don't have scallops' eyes and brains, it's really hard to imagine what the world would be like if we were the noble scallop. However, scientists think that this unusual system transmits a blurry image (not very clear compared to our vision) but covers a large area. This sightline is more suitable if you have to worry about predators in your environment and have to find food at the same time.Based on behavioral experiments, we determined that scallops respond to moving objects and changes in light intensity by altering their swimming and feeding activities.
Of the specimen of the ornate scallop at the Hong Kong Biodiversity Museum, only the shell remains, meaning the eyes have long since disappeared. Still, on your next visit, you can imagine it peering at you from the bottom of the ocean, and try to imagine how you would look in its reflected vision.
By Elvira Rey Rendondo
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