Text and layout by Ben Waggoner, completed 1/18/01.

Image of living sea urchins from the Smithsonian Institution, Office of Imaging, Printing and Photographic Services. Image of living heart urchin (Brissus laticarinatus) provided by the Gallery of Echinoderm Images, created by the Swedish Museum of Natural History, and is used by permission of Dr. Sumaitt Putchakarn, Institute of Marine Science, Burapha University, Thailand.