Appearance
The checkered puffer, Sphoeroides testudineus, is one of several fish species belonging to the family Tetradontidae, meaning "four teeth". Puffers have four tooth plates arranged in quadrants, with two teeth on the bottom and two on the top (Carpenter 2002). These teeth form a strong, heavy beak capable of cracking through hard prey such as mollusks and crustaceans, as well as sipunculids, tunicates, seagrass and detritus. Puffers are named for their ability to swell by swallowing water or air when threatened. They have no spinous dorsal fin, absent or reduced scales, sandpapery denticles on various areas of the body, and a reduced gill opening. Identification of species is determined in part through color, pattern, and the presence and number of spines and fleshy tabs, or lappets, on the skin (Robins & Ray 1986).

