Scientists Amazed at Discovering Fast-Evolving 'Walking Sharks' in Papua New Guinea

A walking shark was discovered by scientists on a remote outcropping on the Papua New Guinea coast on May 3, 2022, at dusk.

The small, tan-and-black-speckled shark slithered across a tide pool with just enough water to cover its belly while using its fins to propel itself forward.

While dragging its body across the shore, it moved like a waddling sea lion. The new discovery of walking sharks immediately sparked a new study.

Epaulette Shark

The animal was an epaulette shark (Hemiscyllium ocellatum), which can walk on land, unlike any other shark species. In a recent Shark Week special for Discovery Channel called "Island of the Walking Sharks," biologist and conservationist Forrest Galante shared previously unreleased footage of this unusual species.

Galante said that this is so amazing because it's the first time in recorded history that one of the Papuan epaulette species has been seen walking.

Epaulette sharks, a species found all along the northern and southern coasts of Australia, are thought to have evolved the ability to walk since it allowed them to forage for food in areas where other sharks couldn't.

Gavin Naylor, the Gainesville Florida Museum of Natural History director for the Florida Program for Shark Research, said that all traits are chosen for when they help a species survive and eke out a living in a safe environment with access to food.

Epaulette sharks, which can reach a length of about 3.3 feet, dive into shallow coral reefs in search of their preferred food, crabs, and other invertebrates. They are content to hang out in tide pools and eat these creatures when the tide recedes. As Naylor noted, once they finish, they are trapped. To get to the next tide pool, epaulettes have learned to climb up in the reef.

Epaulette sharks can haul themselves 100 feet or more across dry land. And using fins for walking is not the only adaptation that allows them to do so. According to a previous article by Live Science, this species can survive when oxygen is in short supply and can stay on land for up to an hour on a single breath. Additionally, this ability enables epaulettes to flourish in low-oxygen tide pools.

Speedy Evolution

In a 2020 study that was published in the journal Marine & Freshwater Research, scientists concluded that the ability to walk in epaulette sharks probably evolved within the last 9 million years. To put that into perspective, the Natural History Museum in London estimates that hammerhead sharks, one of the most recent shark groups, evolved roughly 45 million years ago. This makes the evolution of the epaulette shark quite fast. Naylor also mentioned that epaulette sharks may be creating new species at a startlingly rapid rate. Due to the sharks' unusual mobility, isolated small populations are common.

Naylor continued to explain that geographical barriers, such as a river, could move just far enough to isolate a few sharks from the rest of the population. As these populations' genes randomly mutate and adapt apart from other gene pools over time, they may eventually become genetically distinct.

Because the species' populations have such low genetic diversity, scientists are interested in it. So how could it produce individuals with such a wide range of physical characteristics? No two individuals of the epaulette shark have the same pattern in their distinctive spots, and Naylor and other researchers think that epaulettes may be able to change their patterns and colors at will.

Naylor said that although it hasn't been proven yet, they are coming to this conclusion, Live Science reports.