there are things
— loren eiseley
- The jellyfish is one of the simplest creatures that has ever existed.
- It is the oldest living animal species that has more than one organ.
- It has no brain.
- It has no central nervous system.
- It has no spinal column or bones of any sort.
- It has no heart.
- It has no blood.
- It has no circulatory system.
- It has no respiratory system.
- Despite all of the above, it is not simple.
- The jellyfish is, in fact, staggeringly complex.
- Despite centuries of study, very little is known about these creatures. We basically have no idea how they do almost anything, because just about everything about them is different from other complex creatures, and remains mostly a mystery to scientists.
- The jellyfish is not, even vaguely, a fish.
- It has brain cells, dispersed throughout its body and tied into to a neural network that communicates information neuron-to-neuron, not through a centralized system. So it is, essentially, intelligent everywhere, and cannot ‘die’ (or be rendered ‘unconscious’) through injury.
- It has thrived for 650 million years.
- There are over 10,000 enormously diverse jellyfish species, some of them microscopic, some of them with ‘bells’ over a meter across and tentacles over 100 feet long, and weighing up to a quarter of a ton.
- Some species have 24 eyes, which enable them to see 360-degrees in three dimensions, though only 2 of its eyes, apparently, can see in colour.
- It can fire venom through millions of tiny barbs fired through tiny tubes on its tentacles, in some species enough to paralyze or kill a human adult.
- Before it fires venom, it analyzes the chemistry of what it is touching to ensure it is either food or threatening (and hence worth immobilizing), but even taking time for this analysis it still fires at a speed 10 times faster than a car air-bag inflates in an accident, and faster than a bullet, and at a pressure of up to 2,000 psi, enough to penetrate deep into the skin of most creatures it encounters.
- The tentacles of a jellyfish can continue to detect threats or food, and to fire venom accordingly, long after the tentacle is separated from the ‘rest’ of the jellyfish.
- It reproduces both sexually and asexually, through a wide variety of ways, including (usually daily) spawning, splitting (division into two creatures), self-cloning, and ‘budding’ (producing new organisms on various parts of its body).
- Some species can revert from adults back to immature polyp form when threatened, and then ‘re-grow’ into ‘adults’, over and over, and are hence theoretically immortal.
- Jellyfish polyps can remain dormant for years, if the environment is not ideal, before starting to grow and reproduce.
- Most jellyfish ‘die’ by wearing out and decomposing, usually within a year of maturation, or by being eaten by creatures who have a natural immunity to their toxin.
- Korean robots have been developed to ‘kill’ large blooms of unwanted jellyfish (they have been clogging and shutting down the cooling systems of nuclear reactors, coal-fired power plants and desalination plants, and destroying oceanic salmon farms) by shredding them, but biologists think this will actually increase populations because “when you cut open jellies, you get artificial fertilization — that’s how aquarists get eggs and sperm from species that are difficult to spawn; all those embryos will then metamorphose into polyps which can live for years and clone themselves”.
- Jellyfish move with an efficiency (energy produced / energy used ratio) 50% greater than any other sea creature. We’re not at all sure how they do that.
- Some species are bioluminescent — they can create their own light to hunt in darkness.
- Some large-mass jellyfish live at ocean depths greater than most other creatures can tolerate. Biologists are just beginning to discover the nature of these even-stranger species. A deep dive off Chile last year unearthed a huge never-before-seen jellyfish with multiple solid ‘legs’ and ‘feet’ that was able to self-propel at astonishing speed in any direction and turn on a dime; photographed but uncaptured, its constitution and lineage remain a complete mystery.
- The collective biomass of jellyfish is so large that their vertical daily and tidal migrations are believed to affect ocean food systems and indirectly even ocean currents (they compete for food with krill, whose global biomass is second only to bacteria, and greater than that of humans)
- Jellyfish, at various stages of development, often form ‘colonies’ that manifest behaviours that resemble those of a single ‘creature’ more than those of a collective. If they are sharing intelligence between bodies exactly as they share them within a ‘single’ body, where exactly does one creature end and the next begin? The Portuguese Man-o’-War, a dangerous jellyfish-like ‘entity’ almost as ancient as the jellyfish, is in fact not a creature at all, but a collective of four specialized types of polyp (whose functions are, respectively, mobility, reproduction, digestion and defence) which have evolved together and now cannot survive independently. [And some octopi, which are immune to the Man-o’-War toxin, carry torn off Man-o’-War tentacles as weapons to use against other prey.]
So here we humans are, clumsy, fragile, watery bags of bones and organs, neophytes in this world of unfathomable ancient complexity. Still drawn to the ocean, from where we came. Only recently did we come ashore. Who can guess what might emerge after we’re gone. And when it does, whatever it is, it will probably have to continue to deal with jellyfish.
photo by Mitchell Kaneshkevich
Cheers for sharing :-)
In the words of Daniel Quinn “…and then there was jellyfish.”
wow…! ¿dancing with colorfull jellyfishes?
Thank you. These stagger my imagination… and just in time… for I thought I was getting a handle on things.
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That list is a great read.
Due to anthropogenic ocean changes, jellyfish are now starting to eat ‘up’ the food chain, and using the sequestered extra energy to outcompete humans for ocean resources. heh.