Alice Friedemann must be on the same wavelength as me. This subject of the proliferation of jellyfish caught my attention as well. Since she has done the legwork on this story, I will repost her essay below the following CBC Radio podcast with scientist Lisa-ann Gershwin:

“If jellyfish could wish for perfect conditions, these would include warming and turbid water, lack of predators and competitors, and any conditions that make it harder for other species to survive, like low oxygen or slightly more acidic water than usual. These are the very conditions we are creating at an alarming and increasing rate. And jellyfish are enjoying a renaissance like never before in history.” ~ Lisa-ann Gershwin

A book review of Lisa-ann Gershwin’s “Stung! On jellyfish blooms and the future of the ocean”

[ Xraymike79’s Note: The image above is purely for hyperbole. There are no jellyfish this size. The largest recorded jellyfish is the Lion’s mane jellyfish which can reach a diameter of 7 to 8 feet with tentacles 120 feet long. As Don Howe states below in the comments section: “The power of jellyfish is not in their size but in their vast numbers…”]

Move aside Steven King, jellyfish are worse than any of your demons, worse than any Grade-B monster that’s graced the silver screen.  Unlike The Blob, which can be stopped by freezing, you can’t kill them.  Not with chemical repellents or biocides or nets or electric shocks or introducing species that eat jellyfish like the striped sea slug.  If you shoot, stab, slash, or chop off part of a jellyfish, it can regenerate lost body parts within two days.  Not even the past 5 major extinction events which killed up to 90% of all life on earth, killed off the jellyfish.

Meanwhile they’re on a rampage, doing millions of dollars in damage clogging intakes of nuclear, coal, and desalination plants, killing millions of farmed fish, and destroying fishing nets with their sticky icky bodies.

The more we overfish, pollute, acidify and warm the ocean, create vast dead zones, and trawl ocean bottoms, the better the jellyfish do.

The oceans make the earth habitable for us.  They generate most of the oxygen we breathe, stabilize temperatures, drive climate and weather, and absorb a third of the CO2 we’re emitting.  Over 3 billion people depend on the oceans for their livelihoods; 2.6 billion depend on seafood as their main source of protein.

Most alarming of all, 40% of phytoplankton has died off globally since the 1950s – they’re not only at the base of the food chain, but they generate most of the oxygen we breathe, as well as absorb half of the carbon dioxide, and their increasing death rate will make the ocean get warmer even faster.

Why Jellyfish are taking over the world

Prolific, hard to kill, breed fast, and more – no wonder they’re so successful:

• They’ve everywhere, spread around the world in ship ballast or sea currents.
• Ubiquitous – from top to bottom of the ocean, from pole to pole, year-round.
• Grow faster than other species to quickly take advantage of any food, and they’ll eat almost anything — copepods, fish eggs, larvae, flagellates. They eat past when they can keep consuming, spit food out, waste a great deal other creatures could have eaten.  Even when they’re full, their tentacles keep capturing prey.
• If there’s no food, jellyfish can consume their own body mass and get smaller and smaller until they find food again, and rapidly return to normal.  Even when they grow smaller they can still reproduce.
• Consume many times their body weight in high-value food but are of low-value themselves because they provide little energy, ounce for ounce, compared to the food they ate.  So they have few predators.
• When 2 weeks old they can lay 10,000 eggs a day that hatch 12-20 hours later
• They reproduce many ways: massive orgies, fission, fusion, cloning, hermaphroditism, external fertilization, self-fertilization, copulation.
• If they lose a body part, they can regenerate it within 2 days.
• They are the “Last Man Standing” in eutrophication zones because they need less oxygen
• Many species can tolerate any salinity level, from fresh water to salt water
• They’ve survived ice ages, hothouse climates, all five mass extinctions, predators, competitors, and us.
• Jellyfish in the oceans have been known to live over 10 years
• Many of them avoid predators by long vertical migrations from the deep sea to the surface at night and back down again by daylight

They can wait a long time for the right conditions to bloom

Just as plants have seeds which can endure many years waiting for optimum conditions to grow, jellyfish have a seed-like state called a polyp that waits for good conditions, and can clone themselves to create armies of ‘seeds’ waiting to burst into jellyfish blooms seemingly overnight. Polyps don’t “grow up” to become jellyfish.  They spawn what we think of as jellyfish – the medusa — which then mate sexually to produce polyps, which stick to rocks, shells, man-made structures, plastic, etc.  Both the polyps and the medusa could be considered “immortal” – when a polyp dies it’s clones live on, and when the medusa form of jellyfish dies, it’s pieces turn back into polyps (though I wasn’t clear if all species or just some do this).

Jellyfish are at the top of the food chain

That seems so wrong– a primitive brainless blob?  But jellyfish eat much larger clams, crabs, starfish, snails, and fast, smarter fish and squid.

They’re also at the top because not much wants to eat them.

Worse yet, they outcompete other sea life by devouring the eggs and larvae of species that would have grown up to eat jellyfish larvae.  It’s a double whammy since these larvae never grow up, leaving a lot more food for jellyfish to consume. A jellyfish bloom can clear the water of all eggs, larvae, copepods, and small plankton in less than a day.  This makes it almost impossible for some overfished species to make a comeback.

Read the rest…….