Bizarre Species of Walking Sharks That Can Lift Themselves Out of Water Discovered

Four species of walking shark have been identified, almost doubling the number of known species to nine. The skill enables the predator to stalk the reefs in coastal water during low tides, when the water is shallow—and even allows them to lift themselves out of the water to move between pools.

Walking with their fins is a behavior that separates the group from closely related species, like the bamboo shark. The bamboo shark, like the walking shark, is a benthic shark, meaning it lives on the seafloor.

A paper recently published in Marine and Freshwater Research describes the relationship between the nine known species of walking shark, including four that have been described in the last ten years. They identified the four new species by comparing parts of the DNA passed that is from mother to offspring in individual sharks.

The nine known species can be found in the subtropical waters of the Indo-Australian Archipelago, where they each inhabit a small range.

Genetic data suggests the different species evolved after they separated from the original population, spread to new areas and became isolated.

"They may have moved by swimming or walking on their fins, but it's also possible they 'hitched' a ride on reefs moving westward across the top of New Guinea, about 2 million years ago," Christine Dudgeon, a research fellow in the School of Biomedical Sciences at the University of Queensland, said in a statement.

The species can be found in an area known as The Coral Triangle, which includes waters around New Guinea and north Australia. The researchers describe the region as one of the "most biodiverse" places on the planet.

The rich biodiversity can partially be explained by tectonic plate movement during the Miocene epoch (circa 23.03 to 5.3 million years ago), which is thought to have completed Australia and New Guinea's move north after its breakaway from the supercontinent Gondwana. This was a large land mass that once included what is now Africa, South America, Arabia and India. Plate collisions created a new island as well as a shallow sea habitat, the researchers say. This, in turn, increased levels of marine biodiversity in the region.

The creation of new landmasses and the movement of older landmasses may have not have only helped creatures hitch a ride on travelling reefs, but also created barriers that isolated populations. Ultimately, this separation between populations could lead to the development of new species.

Walking Shark 2
Hemiscyllium halmahera, one of nine known species of walking shark. Mark Erdmann

As a group, walking sharks are small, averaging at 70 centimeters (27.5 inches) and reaching a maximum length of 107 centimeters (42 inches). They are active at night and do not pose a threat to humans, the researchers are keen to stress.

"At less than a metre long on average, walking sharks present no threat to people but their ability to withstand low oxygen environments and walk on their fins gives them a remarkable edge over their prey of small crustaceans and molluscs," said Dudgeon.

"We believe there are more walking shark species still waiting to be discovered," she added.