Spiny, small, and edible, sea urchins are found in oceans all over the world. Their spines can be long or short and can cause great injury in their own right. In addition, some sea urchins' spines are venomous. Divers are familiar with how to deal with a sea urchin sting, and readers will be, too. From why sea urchins sting to the rest of their body structures, this volume's science content gives a great overview of this fascinating creature. Full-color photographs take readers into the ocean to see sea urchins up close—but not close enough that they'll get stung.