Sand tiger shark in South Africa. Photo: Flickr, Creative Commons, Derek Keats.

CHARLESTON (USA)- Scientists at the College of Charleston in South Carolina have been mapping the existing shark species and found amongst the 574 species they discover, 79 potentially new ones.

The outcome of the genetic analysis, which was reported in the Bulletin of the American Museum of Natural History, suggests more overlooked species than scientists anticipated, raising concerns that populations of new species are quite small and endangered and is fuelling biologists’ debates over the organisation of the family tree of these animals.

Sharks and rays are key predators in marine ecosystems, but the life cycles and population numbers of many species remain poorly understood. The family tree of these animals — which are part of the elasmobranch subclass — has proved similarly opaque, with little agreement among researchers over their evolutionary relationships.

The researchers say they were “flabbergasted” by the result, especially because the sequencing covered only around half of the roughly 1,200 species thought to exist worldwide.

The huge number of new species found raises immediate conservation concerns — the reason that some of these purported new species have gone undetected is probably their close resemblance to already-identified species. The populations of such species may, therefore, be even smaller than estimated, as what was thought to be one population may instead be several smaller populations of separate species.

For example, the endangered scalloped hammerhead (Sphyrna lewini) is actually two separate species. Scalloped hammerheads in general have taken a huge hit, so it may be even worse than has been documented if there’s more than one species out there.

Read more at Nature Magazine