To some people, a walking shark may be their worst nightmare. Often imagining a 20-foot monster with razor-sharp teeth, they would be baffled to see that the species within Hemiscyllium are small (up to 42 inches or 107 centimeters in total length but average 28 in or 70cm) and that not much is known about them. Also known as epaulette sharks, the walking sharks are nocturnal and feed on benthic crustaceans, worms, and small bony fish. Restricted to a ring around Northern Australia, the island of New Guinea and the satellite islands of Raja Ampat, Aru and Halmahera in eastern Indonesia, there are nine currently recognized species that call this region home. The most intriguing thing is that all of these benthic sharks share a unique form of locomotion where instead of swimming, they use their highly muscular paired fins to essentially walk along the ocean floor while foraging.

A walking epaulette shark, Hemiscyllium freycineti, crawls across the seafloor in Raja Ampat, ... [+] Indonesia.

David Attenborough helped make these sharks famous a few years ago when he showcased not only these bizarre prototype legs in action but also commented on their unusual physiological adaptation to coping with hypoxic conditions during low tide periods. Having evolved the ability slow their heart rate and breathing, they can gradually limit blood flow to certain parts of the brain, so they can stay during the more extreme tides and exploit the riches of the reef without being picked off by bigger sharks. As it turns out, a new paper from Conservation International, the University of Queensland, the Indonesian Institute of Sciences, the Australian CSIRO and the University of Florida, published in the journal Marine and Freshwater Research, showsthat these walking sharks are the most recently evolved shark species on Earth.

We found the sharks, which use their fins to walk around shallow reefs, only split off evolutionarily from their nearest common ancestor about 9 million years ago, and have been actively radiating into a complex of at least nine walking sharks ever since, said Dr. Mark Erdmann, Conservation International Vice President of Asia-Pacific Marine programs and co-author of the paper in a press release. That may seem like a long time ago, but sharks have ruled the oceans for more than 400 million years. This discovery proves that modern sharks have remarkable evolutionary staying power and the ability to adapt to environmental changes.In other words, this new discovery contradicts the long-held perceptions that sharks are slow to evolve.

Tissue samples were collected from wild specimens and those in museum collections and DNA was then extracted for this project. Using the DNA of these sharks, we were able to estimate when the sharks evolved as well as investigate the processes leading to speciation.We found that changes in sea levels, new reef and land formations and movements of the sharks all played a role, said the papers lead author, Dr. Christine Dudgeon, a research fellow at the School of Biomedical Sciences at the University of Queensland. This information is important not just for walking sharks but for understanding how species have evolved in this region of highest tropical marine biodiversity globally.

The epaulette shark (Hemiscyllium ocellatum) is just one of nine described species.

The genus Hemiscyllium has been recorded from the Late Cretaceous period through to the Eocene epoch from numerous fossil deposits of teeth in Europe (Belgium, Germany, Denmark, Sweden, UK, France), North and Central America, North Africa and India. Following the Eocene epoch, there is a lack of fossil records for this genus until the Pleistocene and the study suggests this supports a recent species radiation. "The walking sharks in the genus Hemiscyllium represent the most recent radiation of sharks, which are likely still differentiating in western New Guinea. These sharks provide a rareand exciting opportunity for us to see evolution in action in a group whose origins predate dinosaurs by 200 million years," said Gavin Naylor, director of the Florida Program for Shark Research at the Florida Museum of Natural History and co-author on the paper.

The authors agree that Hemiscyllium provides an interesting case study to examine speciation in the IndoAustralian Archipelago for these longtailed carpet sharks with very little dispersal throughout their life stages. Due to their isolated habitat ranges, the sharks face a number of threats including habitat degradation and overfishing and their the International Union for Conservation of Nature (IUCN) Red List assessments vary from Least Concern (LC) to Vulnerable (VU) depending on the species; only three of the nine known species are included so far. A global recognition of the need to protect walking sharks will help ensure they thrive providing benefits for marine ecosystems and to local communities through the sharks value as tourism assets. Its essential that local communities, governments, and the international public continue working to establish marine protected areas to help ensure our oceans biodiversity continues to flourish, said Erdmann.

Epaulette shark (Hemiscyllium ocellatum), on reef, at night. South Pacific. (Photo by ... [+] Auscape/Universal Images Group via Getty Images)

Here's hoping this latest research helps these sharks take a step closer to better management.

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Walking Shark Are The Most Recently Evolved Shark On Earth - Forbes