Cute as a Button

Porpita porpita—the blue button jelly —is a neustonic species mostly found in the tropics; that is, it floats right neat the surface of the water. The circular disc is made of chitin and filled with gas, allowing these jellies to float. The tentacles (zooids) radiating from the disc do all the feeding. MIT/WHOI graduate student Kelly Rakow collected this one while diving in the waters near the Liquid Jungle Lab in Panama.  (Photo by Kelly Rakow, Woods Hole Oceanographic Institution)