SCIENCE
movements that they cannot control. An example: if I step on a piece of broken glass, my body realises this and before I can make a conscious decision about what I should do, a reflex pulls my leg up and away from this source of pain. However, this reflex-reliant species now has a problem. Without any proper control of its movements, it must rely on ocean currents, and a certain degree of luck, to find prey – which is why, incidentally, we often see jellyfish washed up on beaches around the world. Any children reading might now want to turn away, because here comes the grown-up part: of Jellyfish and Men. The jellyfish’s collective consciousness of nerves seems to set them apart from us, with our brains. But if they’re unlike us on an individual and physical level, perhaps they’re quite like us in a sort of sociological way. Are we not metaphoric medusozoans? People often talk about our collective ‘national’ mind, about the ‘mind of humanity’ or the psychology behind leadership and groups. Isn’t this something like the nerves of the jellyfish? Couldn’t, then, our social relations be little more than the triggering of reflexes beyond our control and the failure to realise that we are subject to a predetermined fate? Or perhaps we are simply each of us our own jellyfish, with each responding to his or her environment with inbuilt reflexes of prejudice and hate. Perhaps that’s why we enjoy being swept up on political tides, dreaming about the bright future we’ve been promised, only to be left to drown and evaporate on a beach. Perhaps we aren’t jellyfish at all. Maybe we’re only human.
to contract, pulling my fingers to where they need to be to press the desired keys. The same thing is happening inside of you as you read this: your cells are respiring to create the energy they need to keep the page level and keep your eyes looking at it. Now, not only is a jellyfish incapable of typing or reading an article (a fact I hope you have already figured out), but it also doesn’t have any blood at all – or a heart, for that matter. It gets the nutrients to its cells by a process known as diffusion. Through diffusion, nutrients get from our bloodstream into our cells. But it can also happen outside of our bodies. To put this into the sort of context any reader young at heart will understand, diffusion is the reason we will be able to smell a fart from within five metres. The particles will diffuse towards our noses, and across the room, so we smell them! This is how the jellyfish gets its nutrients. No, alas, not by farting – by diffusion. A jellyfish’s body has evolved so that nutrients, like oxygen, will diffuse through its ever-so-thin skin (which is usually only a couple of cells thick) and then arrive at the cells where it’s needed. No heart necessary. Now, as with any zombie film, it’s time to get to the really good bit: the brains. I mentioned that jellyfish only have small nerve clusters. Well, interpret this how you will; I guess these are brains of a sort. You see, these nerves aren’t really what we might define as a ‘brain’. Jellyfish can’t really see – or hear, or taste, for that matter. However, our aquatic acquaintances do have some cells that can sense things like light, salinity and temperature; they also keep them balanced. To do this, they have to rely on reflexes, automatic
Jack Probert (Year 10) thinks about what it’s like to do no thinking at all
In the midst of all these pieces on axons and Article 50s, synapses and Steve Bannons, I would like to offer some reflections on jellyfish. This is because, rather like the members of a Simon Cowell boyband, they have no brains. Yes, for this article, it’s sayonara cerebellum, and bye-bye Broca’s area. These gelatinous old dears have none. Zilch. Zippo. Nada. But – I hear you shout – how are they still alive with some feeble nerve clusters where their brains should be? A particularly robust cardiac system? Funnily enough – and much like the tabloid journalists who report on Cowell’s boybands – they don’t possess a heart, either. Spare a thought for the unfortunate being, both Scarecrow and Tin-Man at once. Nor is there the courageous endurance of a Lion: if it washes up on a beach, the jellyfish’s body, 95 per cent water, evaporates. So again: how do these marvellous medusozoans get away with it all? The ability to survive without what you’d imagine to be some pretty important organs is down to the jellyfish’s simplicity. Let’s explore this strange sea nettle in a little more detail. First, the heart. As you may have noticed, you have blood. This carries nutrients such as glucose (a sugar) and oxygen to our cells, allowing them, in short, to create the energy they need. For example, I am only able to type this because the muscle cells in my fingers and my arms are respiring (that is, creating the energy they need through a chemical reaction), and so are able
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