I just went back and saw your question about spines. No, the red don't have spines, they have what looks like small leaves on the outside of the fruit but it is not sharp. They peel really easily, the peel just pulls away from the flesh. Now I see the yellow variety on that link you posted. The link also mentions the confusing naming of another cactus fruit that grows in the northern Mexico desert and is also called pitahaya, both pitahaya agria (sour) and pitahaya dulce (sweet). It's not related and doesn't look or taste like the what I consider the 'real' pitahaya but it can cause a lot of confusion when people move here from the desert areas.
