Sea urchin
Sea urchins or urchins () are typically spiny, globular animals, echinoderms in the class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal to . Their tests (hard shells) are round and spiny, typically from across. Sea urchins move slowly, crawling with their tube feet, and sometimes pushing themselves with their spines. They feed primarily on algae but also eat slow-moving or sessile animals. Their predators include sea otters, starfish, wolf eels, and triggerfish.
Saving Planet Earth
Of the seven remaining species of sea turtle, six are seriously threatened with extinction. Saira Khan travels to Sri Lanka, one of the best places in the world to see turtles, but even here commercial fishing practices and pressure on the turtles' nesting beaches are driving numbers down.