What great discovery did Detlev Arendt make in 2001?
Arednt discovered that the eyes of invertebrates (e.g., worms, insects) and the
eyes of vertebrates (e.g., fish mammals) evolved separately with no common
ancestry.
Arednt discovered that polychaete worms have two types of animal
photoreceptors, one like the eye of any other invertebrate and one that seemed
like a primitive version of the eyes that vertebrates have.
Arednt discovered that some invertabrates, such as polychaete worms, have no
eyes. This indicates that the sense of sight must have evolved after the evolution
of vertebrates.