Next time you water you cactus, instead of pouring the water into the dirt, pour the water over the top of the cactus. I like to dribble the water on the top and let it naturally climb down the needles of the cactus. That way the cactus gets a nice slow natural feeding.
Our world is so amazing with its details. Because of gravity, plants like cactus with spikes can get watered very slowly over time. Without gravity, the water would never slowly drip down the needles. We have just enough gravity to feed our cactus worldwide.
This was shot with my iPhone using the Photojojo macro lens attachment photojojo.com/store/awesomeness/cell-phone-lenses/new