(a) The eyes seen in planaria, insects, octopus and vertebrates vary greatly in their structure. These organisms can be used for studying evolution of eyes as the eyes of planaria are simple without lens, insects have compound eyes and vertebrates have highly specialized eyes. However, all of them perform the same function of vision. Hence, a common evolutionary origin can be established.
(b) Birds like reptiles have developed wings. Although the way the wings are used is different because it was used for providing insulation from cold in case of reptiles whereas it is used for flight in case of the birds. But this shows that wings are analogous organs and the reptiles and birds adapted in a similar manner in hostile conditions.
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