Lightning Whelk  Sinistrofulgur sinistrum Lightning Whelk  Sinistrofulgur sinistrum The Lightning Whelk is named for the lightning strike patterns found on juveniles. This gastropod can grow up to 16 inches. They are unusual in that they have a left-handed whorl unlike other gastropods with right handed spiraling. These whelks are carnivorous, finding their prey by sight and smell. They prefer bivalves, and eat about one clam-like animal a month. They hunt down prey, then insert the edge of their shell between the opening edges of the victim's shell, and pry it open. If that fails they use their shell to grind a hole in the shell. The radula (tiny teeth) and proboscis (nose) are used to scrape out the soft tissues. The somewhat similar Pear Whelk is smaller, with a rounded pear-like shape, growing to 5 ½ inches. Its color is yellowish, with brown axial streaks. Live shells should never be taken from any Florida State Park.