Walking sharks discovered in tropics

An international team of researchers have discovered four new species of tropical sharks that use their fins to walk in ocean waters off northern Australia and New Guinea.

The four new species brings the total number of known walking sharks to nine.

University of Queensland biologist Christine Dudgeon is lead author of the 12-year study, published January 21, 2020 in the journal Marine & Freshwater Research. Dudgeon said the ornately patterned sharks, which feed on small fish and invertebrates, use their fins to walk in very shallow water. She said in a statement:

At less than a meter 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 mollusks.

These unique features are not shared with their closest relatives the bamboo sharks or more distant relatives in the carpet shark order including wobbegongs and whale sharks.

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Long mottled pink and brown fish with sturdy front fins on a rock.
Walking shark Hemiscyllium halmahera. Image via Mark Erdmann/ University of Queensland.

Dudgeon talked about the study:

We estimated the connection between the species based on comparisons between their mitochondrial DNA which is passed down through the maternal lineage. This DNA codes for the mitochondria which are the parts of cells that transform oxygen and nutrients from food into energy for cells,” Dr Dudgeon said.

Data suggests the new species evolved after the sharks moved away from their original population, became genetically isolated in new areas and developed into new species.

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 two million years ago.

We believe there are more walking shark species still waiting to be discovered.

Bottom line: Four species of walking sharks were discovered in tropical waters.

Source: Walking, swimming or hitching a ride? Phylogenetics and biogeography of the walking shark genus Hemiscyllium

Via University of Queensland

January 29, 2020

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