Some species of sharks have evolved to literally walk along the ocean floor (no, not on land) using their fins as feet. New research Conservation International's Mark Erdmann and colleagues determined that walking sharks only evolved their unique capability 9 million years ago, "making them the 'youngest' sharks on our planet." Of course, a distinct species usually forms when some members of a species are physically separated from others. So how did that speciation occur in the case of the walking sharks? From an interview with Erdmann at Conservation International:
For most of the walking shark species, our findings support the idea that speciation occurred because the populations slowly expanded their range by walking or swimming, then some individuals eventually became isolated by environmental factors such as sea level rise or the formation of large river systems that broke up their habitats.
For the four walking shark species found at the Bird's Head Seascape, we suspect that they actually hitched a ride — on a drifting island…
Q: Is there another mystery about walking sharks you hope to solve?
From a scientific perspective, there is still so much to learn from walking sharks. We know that the world's species that exist today are basically the existing "genetic reservoir" (raw genetic material) we have to adapt to global changes. We also know that walking sharks are very resilient to warm water and that they have a tolerance for oxygen deprivation. Any time you have an animal or plant that can survive in these extreme conditions, there is typically something unique about their genes — a "special sauce". Exploring the genetic basis behind these unique traits in walking sharks could give us invaluable knowledge as we try to adapt to the impacts of climate change.
"Walking, swimming or hitching a ride? Phylogenetics and biogeography of the walking shark genus Hemiscyllium" (Marine & Freshwater Research)
image: "Hemiscyllium michaeli, the leopard epaulette shark, is a species of bamboo shark in the genus Hemiscyllium. It is a tropical shark known from the shallow ocean in the Milne Bay region of eastern Papua New Guinea." © Conservation International photo by Mark V. Erdmann (provided photo)