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Thursday 30 March 2023 Dublin: 10°C
A group of jellyfish float in a tank.
# swim for your life!
Jellyfish are freaks of nature that could take over the world's oceans
They can thrive despite factors such as pollution or a lack of oxygen, and a lack of natural predators has led to a surge in their population.

JELLYFISH ARE TAKING over the world’s oceans, according to marine biologist Lisa-ann Gershwin, who describes their explosive growth in her new book “Stung! On Jellyfish Blooms and the Future of the Oceans“.

That’s because jellyfish are remarkably resilient. They are efficient breeders, “voracious feeders,” and require very little oxygen to survive, reports Tim Flannery in The New York Review of Books.

It’s no wonder these floating creatures have been around for more than 500 million years. Jellyfish are freaks of nature — they can thrive in ocean conditions that kill most other fish and sea animals.

Plastic bags and oil platforms aren’t a problem as jellyfish think these unnatural surfaces make great breeding grounds. Oxygen-depleted areas of the ocean, known as “dead zones“, also don’t seem to be a hazard to jellyfish.

In turn, a lack of natural predators has led to an upswing in jellyfish populations.

While “fish and prawn numbers plummeted” in the wake of Hurricane Katrina and the Deepwater Horizon oil spill, the Australian spotted jellyfish, which showed up in the Gulf of Mexico in 2000, strengthened in numbers, according to Flannery.

“As survivors of an earlier, less hospitable world, they can flourish where few other species can venture,” he writes. “Their low metabolic rate, and thus low oxygen requirement, allows them to thrive in waters that would suffocate other marine creatures. Some jellyfish can even absorb oxygen into their bells, allowing them to “dive” into oxygen-less waters like a diver with scuba gear and forage there for up to two hours”.

There is still some debate as to whether jellyfish may soon dominate the seas. The perception that jellyfish are becoming more common is based on “media fascination” and a lack information about their numbers in the past, according to a study published in the journal BioScience in February 2012.

- Dina Spector

Read: Deadly jellyfish-like ‘Man-of-war’ in Irish waters >

More: Diver stung in face by jellyfish in Skerries >

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