There was an all white snake that was produced from a spider to spider breeding. I do not think that one instance is enough to say that this was a homozygous spider, because this could have easily been due to birth defects. For example the animal could have had many aspects that did not develop including the ability to produce color pigment. The reason the animal did not survive could have been caused by this as well. I have read accounts of low egg production to undeveloped fetuses for this combination. It is nearly impossible to say what the actual cause is from anecdotal evidence. There are many things that can lead to the same outcomes.