Climate Change Is Making Sharks Walk on Land and Scientists Have Managed to Capture It on Tape!

What if we told you that the chances of getting attacked by a shark on land would be slim, but never zero!?

It was just a regular day of observing and recording sharks for the researchers of the Florida Atlantic University on May 3. Except, as night fell, they came across something truly extraordinary: a walking shark!

Before you let your imagination run wild, this was no Great White tip-toeing (or tip-finning?) about, but the much smaller epaulette shark. Epaulets (Hemiscyllium ocellatum) are about 3 feet long, and can be found swimming (and even walking, apparently) in the reef flats around Australia’s southern Great Barrier Reef.

These sharks experience short periods of elevated CO2, low oxygen levels (hypoxia) and fluctuating temperatures as reef flats become isolated from the outgoing tide. And surprisingly, these walking sharks are capable of surviving in the complete absence of oxygen (anoxia) for two hours without any adverse effects, that too at a much higher temperature than most other hypoxia-tolerant animals.

The researchers analyzed differences in the walking mannerisms of neonate (new-born) and juvenile sharks, and found that the differences in their body shapes had no impact on the velocity, fin rotation, axial bending, tail beat frequency and amplitude in the sharks’ early life stages.

The epaulette shark walks both in and out of water and is found within the reef flats around Australia's southern Great Barrier Reef (Florida Atlantic University)

The epaulette shark walks both in and out of water and is found within the reef flats around Australia’s southern Great Barrier Reef

(Florida Atlantic University)

The Florida Atlantic University biologists and their collaborators in Australia believe that these remarkable traits enable the reef-dwelling epaulette sharks to survive in increasingly hostile environments as their habitats change. It enables them to reach areas with plentiful food and less competition, while also giving them better agility to evade predators.

Apart from being key to their survival, however, such locomotor traits may also be related to their sustained physiological performance under challenging environmental conditions, including those associated with climate change, the study authors add.

Simply put, climate change may be influencing these sharks’ adaptation to walking. In fact, this species happens to serve as the perfect model to understand the kinds of impact a rapidly-warming Earth would have on vertebrates in general, and perhaps even reflect on what oceans would look like in the future.

While these epaulettes are the only sharks that can cover 30 times the distance of their body length in the absence of oxygen, walking sharks have also been described in several studies done in the past. Incidentally, all those studies have been about different species of the Hemiscyllium genera.

All in all, it seems like the epaulettes have made a good start on how they will adapt to the trying times brought about by climate change. What’s left is for us to further investigate what factors affect the walking and other unique talents of these fascinating beings.

The findings of this study are detailed in the journal Integrative & Comparative Biology and can be accessed here.


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