Purple Sea Urchin

This purple urchin Paleopneustes cristatus is seldom seen by itself, and can be found in groups of hundreds. Dr. Dave Pawson, a senior scientist at NMNH who studies deep-sea echinoderms, is testing if the fertilized eggs of this urchin sink or are buoyant, an important question in figuring out this urchin's life cycle. This urchin specimen was collected at around 800 feet during the 2012 field season of the Deep Reef Observation Project (DROP).

Notice the "mohawk" look of this urchin. They keep their top spines angled over the three large pores through which eggs or sperm are released. It is thought that this covering with spines protects the pores from parasites or predators.