Eyes also fall into two groups on the basis of their photoreceptor's cellular construction, with the photoreceptor cells either being ciliated (as in the vertebrates) or rhabdomeric. These two groups are not monophyletic; the Cnidaria also possess ciliated cells, and some gastropods and annelids possess both.
Eyes also fall into two groups on the basis of their photoreceptor's cellular construction with the photoreceptor cells either being ciliated (as in the vertebrates) or rhabdomeric These two groups are not monophyletic; the Cnidaria also possess ciliated cells and some gastropods and annelids possess both