A newly-discovered species of hammerhead shark was discovered; it remained unrecognized throughout history because it has no outward differences from the common scalloped hammerhead.
The shark was dubbed the Carolina hammerhead (Sphyrna gilbert). The researchers noticed the scalloped hammerheads they were collecting had two distinct genetic signatures in the mitochondrial and nuclear genomes, a University of South Carolina news release reported.
After looking back on past records, the team found that Carter Gilbert, a famous curator of the Florida Museum of Natural History who held his position from 1961 to 1998, had described an unusual hammerhead in the year 1967.
The specimen had 10 fewer vertebrate than Sphyrna lewini (the then-believed lone species). The newest specimens, discovered near Charleston, seemed to match this "cryptic" breed.
The team named the species S. gilbert in honor of the curator that first discovered it.
"Outside of South Carolina, we've only seen five tissue samples of the cryptic species," University of South Carolina ichthyologist Joe Quattro, said. "And that's out of three or four hundred specimens."
Shark populations have become severely threatened over only the past few decades. The sharks (at least the Sphyrna lewini, whose behavior is better-known) swim in schools of up to hundreds of animals during different parts of the year, Montery Bay aquarium reported. This makes the species exceptionally vulnerable to hunters that target these large groups.
"The biomass of scalloped hammerheads off the coast of the eastern U.S. is less than 10 percent of what it was historically," Quattro said, the news release reported. "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."
Reserchers worry the rarity of the newly-discovered shark highlights the "fragility of shark diversity in the face of relentless human predation."
The findings will be published in the journal Zootaxa.
