Scientists have spotted an elusive shark called the smooth hammerhead shark (Sphyrna zygaena) in the archipelago off the coast of Ecuador for the first time in decades. They also may have found a critical smooth hammerhead shark nursery. The smooth hammerhead and scalloped hammerhead sharks (Sphyrna lewini) may look alike at first glance, but some subtle differences can help tell them apart. Researchers measure a juvenile smooth hammerhead shark in the waters of the Galápagos islands. Just like other hammerheads, smooth hammerheads are threatened by overfishing.