Right: Image of a spine taken with a scanning electron microscope (SEM). It reveals why the spines of jumping cholla are so tenacious and difficult to pull out. The spine is covered with sharp, overlapping scales or barbs that lie flat and allow the spine to penetrate skin readily like a very sharp needle. When you try to remove a spine, you are pulling against hundreds of tiny scales. In the process, other spines penetrate the skin from all directions, making the extraction very painful and seemingly hopeless. This spine was removed from a student's foot on a field trip to Anza-Borrego many years ago. The student had access to a SEM. Needle-nose pliers are a handy tool to carry when walking through jumping cholla country.