New 'Carolina Hammerhead' Shark Species Gets an Official Name

A rare, new species of hammerhead shark living in waters off the South Carolina coast now officially has a scientific name, solidifying its place as a unique member of the animal kingdom.

The Carolina hammerhead, as the shark has come to be known, looks identical to the common scalloped hammerhead (Sphyrna lewini). Reports of the new hammerhead species date back to 2006, when National Geographic reported on a new, but unnamed, species of hammerhead shark identified by University of South Carolina ichthyologist Joe Quattro. 

The Carolina hammerhead has finally been described in the scientific journal Zootaxa, where Quattro and his team officially named the shark Sphyrna gilberti.

While the shark has been unofficially known as the Carolina hammerhead for years, until now it was only scientifically classified as a "cryptic species," one that is physically indistinguishable from the more common species.

Differentiating between a Carolina hammerhead and a common scalloped hammerhead will be nearly impossible for the average seafarer. The only discernible difference between the two species are the number of vertebrae each has.

"Carolina hammerheads have 83 to 91 vertebrae, while scalloped hammerheads have 92 to 99 vertebrae," South Carolina newspaper The State reported in August when Carolina hammerhead news first reemerged. 

Carolina hammerheads also have a different genetic signature than their scalloped counterparts, which is what first tipped Quattro off that the shark could be a new species when he was studying marine life populations is the coastal waters of South Carolina.

Quattro went on to dig back in the scientific record to find that in 1967, scientists documented an anomalous scalloped hammerhead with 10 fewer vertebrae than it should have.

The Carolina hammerhead's scientific name, Sphyrna gilberti, is an homage to the man who first documented the cryptic species, Carter Gilbert, a renowned curator of the Florida Museum of Natural History from 1961 to 1998.

While there have been isolated occurrences of the Carolina hammerhead being documented in far away seas, it appears the species has a preference for the US Coast.

"Outside of South Carolina, we've only seen five tissue samples of the cryptic species," Quattro said. "And that's out of three or four hundred specimens."

The shark's rarity has persisted over time, though the overall strength, or lack thereof, in Carolina hammerhead population is unclear, as shark populations have greatly diminished over the past few decades.

"The biomass of scalloped hammerheads off the coast of the eastern US is less than 10 percent of what it was historically," Quattro said. "Here, we're showing that the scalloped hammerheads are actually two things. Since the cryptic species is much rarer than the lewini, God only knows what its population levels have dropped to."