Editing Convergent evolution (section)

===Eyes===
{{Main|Eye evolution}}
[[File:Evolution eye.svg|thumb|The camera eyes of [[vertebrate]]s (left) and [[cephalopod]]s (right) developed independently and are wired differently; for instance, [[optic nerve]] <sup>(3)</sup> fibres <sup>(2)</sup> reach the vertebrate [[retina]] <sup>(1)</sup> from the front, creating a [[Blind spot (vision)|blind spot]] <sup>(4)</sup>.<ref>{{cite book|last=Roberts|first=M.B.V.|date=1986|url= https://books.google.com/books?id=ASADBUVAiDUC&pg=PA574|title=Biology: A Functional Approach|url-status=live|archive-url= https://web.archive.org/web/20160912091025/https://books.google.com/books?id=ASADBUVAiDUC&pg=PA574|archive-date=2016-09-12|publisher=Nelson Thornes|page=274|isbn=978-0-17-448019-8}}</ref>]]

One of the best-known examples of convergent evolution is the camera eye of [[Cephalopod eye|cephalopods]] (such as squid and octopus), [[vertebrate]]s (including mammals) and [[cnidaria]]ns (such as jellyfish).<ref name="Kozmik2008">{{cite journal|last=Kozmik|first=Z |author2=Ruzickova, J |author3=Jonasova, K |author4=Matsumoto, Y. |author5=Vopalensky, P. |author6=Kozmikova, I. |author7=Strnad, H. |author8=Kawamura, S. |author9=Piatigorsky, J. |author10=Paces, V. |author11=Vlcek, C. |title=From the Cover: Assembly of the cnidarian camera-type eye from vertebrate-like components|journal=Proceedings of the National Academy of Sciences |date=1 July 2008 |volume=105|issue=26 |pages=8989–8993|doi=10.1073/pnas.0800388105|pmid=18577593 |pmc=2449352 |bibcode=2008PNAS..105.8989K |doi-access=free }}</ref>  Their last common ancestor had at most a simple photoreceptive spot, but a range of processes led to the [[evolution of the eye|progressive refinement of camera eyes]]—with one sharp difference: the cephalopod eye is "wired" in the opposite direction, with blood and nerve vessels entering from the back of the retina, rather than the front as in vertebrates. As a result, vertebrates have a [[Blind spot (vision)|blind spot]].<ref name=SCM2005/>