colour receptors

["Bonnie Blackwell, x 3332" <bonn@qcvaxa.acc.qc.edu>]

Some time ago we discussed colour receptors, which made me think about
something as i sat at a stoplight.  

1.  If mammals lost the two colour receptors that both reptiles and birds
had because they did not need them being nocturnal animals, do owls and
other night birds show reduced numbers of colour receptors or reduced
efficiency in the ones they have?
2.  In humans, many males are colour blind, but is that due to 
impaired colour receptors genes (or the lack of one or two due them
being on the X chromosome) or is it due to another biochemical pathway
that screws up development or use of those colour receptors.

i know mickey will get mad at me for the latter none dino question,
so please reply to me off list.
thanks
b

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Bonnie A.B. Blackwell,                          bonn@qcvaxa.acc.qc.edu
Dept of Geology,                                off: (718) 997-3332
Queens College, City University of New York,    fax: (718) 997-3299
Dept of Earth \& Environmental Sciences,        fax: (718) 997-3349
The Graduate Center, CUNY,                      fax: (718) 997-3513
Flushing, NY 11367-1597                         messages: (718) 997-3300