Post by jayant on Feb 3, 2007 13:18:24 GMT -5
The following points are made by E.J.W. Barrington (citation below):
1) Two main types of highly differentiated photoreceptor system have appeared in the invertebrates:
2) Simple types of eyes are seen in the free-living Platyhelminthes and in the Annelida, where they are often composed of sensory cells associated with screening pigment cells.
3) Cup-like arrangements of pigment cells are common in the eyes of polychaetes, but a higher level of differentiation is reached in this group.
Adapted from: E.J.W. Barrington: Invertebrate Structure and Function. Nelson 1967, p.282.
For Details www.cave-biology.org/forum
1) Two main types of highly differentiated photoreceptor system have appeared in the invertebrates:
2) Simple types of eyes are seen in the free-living Platyhelminthes and in the Annelida, where they are often composed of sensory cells associated with screening pigment cells.
3) Cup-like arrangements of pigment cells are common in the eyes of polychaetes, but a higher level of differentiation is reached in this group.
Adapted from: E.J.W. Barrington: Invertebrate Structure and Function. Nelson 1967, p.282.
For Details www.cave-biology.org/forum