Lisa-ann Gershwin has written a book that introduces the reader to the weird and frightening world of jellyfish and their actual and potential effects on the ocean environment: Stung!: On Jellyfish Blooms and the Future of the Ocean. This book should be read by those interested in jellyfish, but, more importantly, it should be read by those interested in the future of our oceans—the actual focus of the work.
Theo Tait wrote a review of Gershwin’s book in the London Review of Books. He provided this summary:
He also provided this assessment of the book:
Continuing in the monster-movie vein, he chose to title his review Water-Borne Zombies.
Given that zombies—and vampires—appear so much in popular entertainment, one has to wonder if we are, perhaps, producing a generation that might be confused about the existence of these mythical creatures. Tait’s reference to zombies is intriguing because some of the attributes of jellyfish bear resemblance to what is commonly thought of as "the undead." Thinking of jellyfish as zombies might prove an interesting means of describing their properties. We shall see.
The best dictionary definition of a zombie is probably this one:
Being will-less, speechless, and capable of only automatic movement are jellyfish attributes, but it was startling to learn that there is at least one species that has learned to regenerate itself after death—that is more than being undead, that is being immortal.
While individual jellies don’t live forever, it seems the species, as a class, may be immortal. Jellyfish are at least a half billion years old. Prior to the Cambrian Explosion where many new species evolved, jellies seem to have ruled the oceans.
The greatest, or worst, of the mass extinctions is known as The Great Dying. This occurred about 250 million years ago and is estimated to have rendered about 96% of all marine species extinct. Yet the jellyfish survived.
Gershwin prefers to think of jellyfish as weeds rather than unnatural monsters. One of the things that make a weed a weed is its ability to survive in conditions where other species fail.
Now we begin to enter the monster movie realm as Gershwin tells us some of the characteristics of jellyfish.
Jellyfish do not spawn another jellyfish. Their offspring is another adult phase as a polyp that anchors itself to some firm object. This polyp phase can persist indefinitely and it can reproduce by cloning. When the polyp feels the time is right it goes through a process called strobilation.
The number of jellyfish offspring produced in a strobilation event depends on the particular species and on the quality of conditions. Some polyps give off a single larval medusa, others give off as many as 50. This "alternation of generations" provides a powerful degree of freedom in adjusting to changing conditions. The polyp phase can simply set and continue reproducing itself until conditions improve for its potential offspring.
Gershwin provides the example of one jellyfish species that has been observed to have a zombie-like path to immortality.
The feeding habits of jellyfish are also monstrous. When food is scarce they seem quite content to eat each other. And if food is really scarce, many forms of jellyfish are able to effectively eat themselves.
Any true monster must be capable of frightening those it comes into contact with. Jellyfish are quite capable of that. Jellies are of two varieties; one stings its prey with special cells loaded into tentacles, and the other entangles prey in merely slimy tentacles. The most common form stings. Wikipedia provides this note:
Luckily, not all stings cause serious effects in humans, but some species can cause extreme illness and even death. The truly monstrous part is that these stinging cells seem to have a life of their own, maintaining their threat even after the host specimen has died. Again, from Wikipedia:
Gershwin provides some examples of the nastiest specimens.
The box jellyfish, native to the waters around Australia, are referred to as "the world’s deadliest animals."
And then there is the nasty little jellyfish known as Irukandji, an Aboriginal word.
One of the "benefits" of globalization is that we have enormous ships that suck water up into ballast tanks in one port and deposit it into the waters of another port across the ocean, thus contaminating one ecosystem with specimens from another. The Irukandji was thought to be limited to the area around Australia.
Jellyfish blooms can create densities of specimens where they are literally cheek to jowl. This density of matter has caused enormous difficulties just by getting in the way. Jellyfish are notorious for clogging cooling vents on everything from aircraft carriers to nuclear reactors. In true zombie-like fashion, they cannot be stopped.
There are occasions where jellies clogging nets are more than a nuisance. Jellyfish can make short work of fish farms if allowed to make contact. Gershwin described one salmon kill that occurred in New Zealand in 1998 when 56,000 3-kilogram salmon were killed within 30 minutes.
Not only do they sting with their tentacles, but they emit slime filled with stinging cells that can be sent out, kind of like a calling card announcing "Watch out, I have been here and I will be back."
In the last chapter of her book Gershwin summarizes all the damage we have done to our oceans by pollution and overfishing and reminds us that degrading ocean ecology almost always leads to more favorable conditions for jellyfish blooms. She chose to call that chapter "The Rise of Slime."
Perhaps one day an enterprising author will produce the screenplay for World War S (or World War J).