Sunday, November 16, 2008

Visual Cells

There are two principal types of visual cells in animals: ciliary-type, typically found in vertebrates and other deuterostomes; and rhabdomeric-type, found in insects, molluscs, and other protostomes. Recently there's evidence that prebilaterians, the common ancestors of deuterostomes and protostomes, may have had both types of cells and that indeed both types of cells can still be found within both groups.
See Jellyfish vision starts with cAMP signaling mediated by opsin-Gs cascade in PNAS and Evolutionary biology: Light on ancient photoreceptors in Science.

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