Researchers have discovered that epaulette sharks, also known as 'walking sharks' because of their ability to walk across the seafloor using their fins, can reproduce without any measurable rise in energy use.
Reproduction is usually incredibly energy intensive for most animals but no-one had measured direct metabolic cost of sharks laying eggs, until now.
The study, published in Biology Open, was based on five mature female epaulette sharks from waters around Magnetic Island and Balgal Beach in Queensland on the east coast of Australia.
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Gaskell
“Reproduction is the ultimate investment … you are literally building new life from scratch,” says Professor Jodie Rummer, a marine biologist at James Cook University (JCU), in a statement.
“We expected that when sharks make this complex egg, their energy use would shoot up. But there was no uptick in energy use, it was completely flat.”
This finding suggests that epaulette shark populations could be more resilient to environmental threats than we thought. “This work challenges the narrative that when things go wrong – such as warming oceans – that reproduction will be the first thing to go,” says Rummer.
“Under environmental stress many species will choose between survival and reproduction, but the epaulette shark might be able to continue to produce eggs, even under such stressors,” says the study’s lead author Dr Carolyn Wheeler. “That’s encouraging, because healthy sharks equal healthy reefs.”
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Top image: Adult epaulette shark curled up amongst corals. Credit: Johnny Gaskell
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