"Jaws" portrayed sharks as man-hunting villains. "Sharknado" imagined a world where they attack from twisters.
But in the real world, sharks are much more complex. Now, researchers have discovered new species of sharks that can walk, according to research published in the journal Marine and Freshwater Research.
This isn't the first discovery of walking sharks, but the new research shows they are the most "recently" evolved shark species on Earth. The findings contradict long-held beliefs that sharks are slow to evolve.
"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's vice president of Asia-Pacific marine programs. "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."
The study was a collaboration between Conservation International, the University of Queensland, the Indonesian Institute of Sciences, the Australian CSIRO and the University of Florida.
"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 paper’s lead author, Dr. Christine Dudgeon. "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 team behind the research hopes more walking shark species, also called bamboo sharks, will be added to the International Union for Conservation of Nature Red List.
To date, only three of the nine known species are included due to previously unavailable data.
The nine known species are mainly found in a ring around Northern Australia, the island of New Guinea and the satellite islands of Raja Ampat, Aru and Halmahera in eastern Indonesia.
Due to their small, isolated habitat ranges, the sharks face extreme vulnerability to localized threats, including habitat degradation and overfishing.
"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," said Erdmann. "It's essential that local communities, governments, and the international public continue working to establish marine protected areas to help ensure our ocean's biodiversity continues to flourish."
The research effort behind the new discoveries took 12 years. The team of scientists observed how the sharks used their ability to withstand low-oxygen environments to walk on their fins to eat small crustaceans and mollusks.
Researchers believe more walking shark species exist and that it's simply a matter of finding where they live.
"The information from this research is very important for Indonesia, and confirms that our marine biodiversity is quite unparalleled," said Andi Rusandi, director of marine biodiversity conservation at Indonesia’s Ministry of Marine Affairs and Fisheries. "This is an important stepping stone in better understanding these unique creatures, and this will pave the way for Indonesian scientists, from the Government, Universities, and civil society to study our endemic walking shark species."