Grown-up sea urchins are typically well secured against a lot of killers by their solid and sharp spinal columns, which can be venomous in some varieties. There are numerous delicate cells in the epithelium, particularly in the spinal columns, pedicellaria and also tube feet, and around the mouth. Although they do not have eyes or eye spots, the entire body of a lot of normal sea urchins could work as a compound eye. As a whole, sea urchins are negatively attracted to light, and look for to hide themselves in gaps or under items. Many varieties, besides pencil urchins, have statocysts in globular organs called spheridia.