How do sea urchins defend themselves?

Sea urchins have several defense mechanisms to protect themselves from predators. Their primary defense is their spines, which can be used to deter or injure predators. They also have pedicellariae, which are small pincer-like structures that are used to keep the surface of the urchin free of debris and unwanted organisms, including parasites. Pedicellariae also help to defend the urchin by snapping closed when they detect movement or touch.

In addition to spines and pedicellariae, some species of sea urchins have venomous spines that can deliver a painful sting to predators or humans. Other species have sticky tube feet that can trap predators or detach to distract them.