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Eye evolution questioned

Invertebrates with vertebrate-like vision challenge the idea that the two groups of organisms have distinctly different visual receptors

Amy Maxmen
The standing dogma of eye evolution is challenged with the discovery of an invertebrate that sees light like vertebrates do, rather than like their more closely related cousins, according to a study published today (March 1) in EvoDevo.
T. transversa larva
Image: Nina Furchheim, Berlin Museum of Natural History
"Now the story is more complicated than it was before, when we thought there was a clear-cut division between vertebrates and invertebrates," said lead author linkurl:Yale Passamaneck;http://www.kewalo.hawaii.edu/martindale/mmpeople.html from Kewalo Marine Laboratory at the University of Hawaii.Animal eyes vary in appearance, but the light-sensing photoreceptor cells within them come in just two varieties: ciliary and rhabdomeric. Vertebrates see light with the ciliary type, which sports a folded, hair-like cilium, while invertebrates see with rhabdomeric photoreceptors, which typically bear bristles. In 2004, biologists hypothesized that an ancestor of both invertebrates and vertebrates sensed light with rhabdomeric receptors -- but also had ciliary...
Terebratalia transversaciliary-opsin
T. transversa adult
Image: Yale Passamaneck
ciliary-opsinciliary-opsinciliary-opsinY. Passamaneck, et al., "Ciliary photoreceptors in the cerebral eyes of a protostome larva," linkurl:EvoDevo,;http://www.evodevojournal.com/content/2/1/6/abstract 2:6, 2011.



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