"which pattern of survivorship is most likely for an organism such as the sea urchin, which produces large numbers of very small offspring and provides no parental care? "

Young individuals have a high probability of dying, but older individuals have a relatively low probability of dying.

Survival rate for adult sea urchins are very high while there is a lower survival rate for younger sea urchins due to higher predation rates and high stress levels associated with warm sea water temperatures. During the spring, the sea urchins spawn and the female sea urchin releases millions of tiny, jelly-coated eggs into the water that are then fertilized by the sperm of the male sea urchin. The tiny sea urchin eggs become part of the plankton and the sea urchin babies (larvae) do not hatch for several months. The sea urchin young will not become large enough to retreat from the plankton and down to the ocean floor until they are between 2 and 5 years old. Due to dredging on the ocean floor and pollution in the water, the sea urchin populations are declining especially the young sea urchin.