Question

Explain the evolution of eyes. Class X. CBSE. 5 marks answer.

Answer 1

Many researchers have found the evolution of the eye attractive to study, because the eye distinctively exemplifies an analogous organ found in many animal forms. Simple light detection is found in bacteria, single-celled organisms, plants and animals. Complex, image-forming eyes have evolved independently several times.[1]

Complex eyes appeared first within the few million years of the Cambrian explosion. From before the Cambrian, no evidence of eyes has survived, but diverse eyes are known from the Burgess shale of the Middle Cambrian, and from the slightly older Emu Bay Shale.[2] Eyes are adapted to the various requirements of their owners. They vary in their visual acuity, the range of wavelengths they can detect, their sensitivity in low light, their ability to detect motion or to resolve objects, and whether they can discriminate

Answer 2

96% of animal species have eyes. The first animal eyes did little but detect light—they helped to establish day/night cycles and coordinate behavior—but more-complex eyes soon evolved. A predator who can see its prey from a distance, or a prey animal that can see the shadow of a predator approaching, has a clear survival advantage over those who can't. Even a slight improvement in image quality provides a significant survival advantage, allowing for the step-by-step evolution of increasingly complex eyes.

The first eye was a photosensitive element which allowed the animal to trace light. Its said to be evolved in Ocean, most of the animals we see today have eyes. But the eyes are different, insects posses compound eyes, arachnids and crustaceans have ocelis and we have an auto focusing eye.

We could group these Organisms and establish that eyes are common to them and hence they have all evolved from a common ancestor. It is quiet sure that they do. But there may be a case that they must have come from some parellel evolution. Consider the case of wings, wings of insects, wings of birds and wings of bats they all evolved independently. There is no relations between insects, birds and bats in terms of aviation, three of them developed flight in there own means. Like this there may be some later development in Science which suggests that the eyes may be formed from any parallel evolution, we are forced to break down our theory.

Planaria, insects, octopus and vertebrates all have eyes. They also all live on earth. Discounting the theory of space squid, the simplest explanation is they all evolved here and if you go back far enough there is a common evolutionary origin for all terrestrial life.

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