In a remote spot on the coast of Papua New Guinea on May 3, 2022, scientists discovered something astonishing: a walking shark. As if on foot, the shark uses its fins to drag its body.
The little speckled brown and black shark moved across the tide pool. It moves like a sluggish sea lion as it drags its body across the shore.
The creature is the epaulette shark or Hemiscyllium ocellatum. This shark is unique among other shark species in its ability to walk on land.
Quoted from Live Science, Forrest Galante, a conservationist and biologist, recently shared rare footage of this unusual species in the Discovery Channel's Shark Week special entitled "Island of the Walking Sharks".
"This is the first time in the history of any of the Papuan epaulette species that it has been documented walking. It is quite extraordinary," Galante said at the event.
Scientists think the epaulette shark, a species found across the southern coast of New Guinea and the northern coast of Australia, developed the ability to walk because it helped them find food in environments where other sharks could not survive.
"All traits are selected when they allow a species to better survive and adapt to an environment in which they are safe and can find food," said Gavin Naylor, director of the Shark Research Program at the Florida Museum of Natural History in Gainesville.
The epaulette shark, which grows to about 1 meter in length, swims to shallow coral reefs to hunt for crabs and other invertebrates, their food of choice. At high tide, they love to hang out in the tide pool and devour these creatures.
"But once they're done, they're stuck. They then learn to climb the reef and plop down in the next high tide pool," said Naylor, who wasn't involved with the Discovery Channel.
The epaulette shark can transport its body as far as 30 m or more across dry land. Walking on flippers isn't the only adaptation they might make.
This species can also survive when oxygen is scarce, spending up to an hour on land on a single breath. This ability helps epaulette sharks thrive in the low-oxygen waters of tide pools.
According to the researchers, the epaulette shark probably developed the ability to walk in the last 9 million years. In a 2020 study published in the journal Marine & Freshwater Research, this is a very rapid adaptation of abilities for sharks. Researchers predict the epaulette shark has the potential to form new species at incredible speed.
One big question about these sharks that scientists are looking to answer is how a species with so little genetic diversity in the population could produce individuals that were so different in their appearance.
The pattern on the distinctive spots of the epaulette shark varies so much that no two individuals look exactly alike, and Naylor and other scientists suspect that the epaulette can actually change its color pattern at will.
"We haven't proven it yet, but we think it is," concluded Naylor.