Sea Urchins
Reproduction of the sea urchin is quite simple. The male releases sperm into the water and the female releases eggs into the ocean water. In some cases, the eggs of the female sea urchin float freely in the ocean water. Other times, the eggs are carried by the spines of the sea urchin for protection. When the eggs are fertilized, the zygote develops into a free- swimming blastula embryo which is a simple ball of cells.