Most fish can see very well and some fish even have a special eye structure called the Tapetum lucidum that allows them to see very small amounts of light. How does this structure work?(look under sharks for answer)

Answer & Explanation:

Vision is simply the sense or ability of sight; the ability to see or the perception of light. Tapetum lucidum present in most fishes especially the nocturnal ones and sharks, is located behind the retina. It is a special eye structure whose function of which is to return rays of light that have escaped from the retina back to the retina to improve vision. This has enabled them to survive in an environment where light readily disappears due to depth.

chordata is the answer