Does a Saguaro or a Prickly Pear need more sunlight?

I believe a Saguaro needs more water. I found this web site very informative on Catus. <a class="url" target="_blank" rel="nofollow noreferrer" href="/to/?target=http://linkjacket.com/jk.cgi?i=7mex03E&d=http%3A%2F%2Fwww.life123.com%2Fhome-garden%2Fplant-guides%2Fcactus%2Fgrowing-saguaro-cactus.shtml&n=NaN">Saguaro or a Prickly pear</a>