Hello, friends!
So the first time I heard about the subsurface ocean on Europa (one of Jupiter’s moons), my imagination ran wild. Or should I say it swam wild? I imagined all sorts of wonderful and terrifying sea creatures: krakens with lots of horrible tentacles and teeth; crab-like creatures scuttling around on the ocean floor; and perhaps even extraterrestrial merfolk with a rich and complex civilization of their own.
As I’ve learned more about space and science, though, I’ve scaled back my expectations for what we might find on Europa. Or on Enceladus, or Dione, or Titan, or Ariel, or Pluto… there’s a growing list of planetoids in the outer Solar System where subsurface oceans of liquid water are suspected and/or confirmed to exist.
Any or all of those worlds might support alien life. But not giant sea monsters. When astrobiologists talk about alien life, they’re usually talking about microorganisms. For Europa, rather than civilized merfolk and tentacle-flailing leviathans, we should imagine prokaryotic microbes clustered around hydrothermal vents, feeding on sulfur compounds and other mineral nutrients. If we ever find evidence that these Europan microbes exists, it will come in the form of a weird amino acid residue, or something like that.
That’s the most exciting discovery we can hope for, realistically speaking. Unless…
On Monday, I introduced you to the term “abyssal gigantism,” also known as “deep-sea gigantism.” Abyssal gigantism refers to the tendency of deep-sea organisms to grow larger (sometimes much larger) than their shallow-water cousins. As an example, see the giant squid. Or if you really want to give yourself nightmares, look up the Japanese spider crab.
The more I read about abyssal gigantism, the more my thoughts turn to Europa (and Enceladus, and all the rest). The environment beneath Europa’s icy crust shouldn’t be so different from the deepest parts of Earth’s oceans. So shouldn’t what happens in the deepest parts of Earth’s oceans also happen on Europa?
According to this article from Hakai Magazine, yes. Yes, it should. The same evolutionary pressures that cause abyssal gigantism here on Earth should cause a similar kind of gigantism on Europa. In fact, it would be strange if that didn’t happen. One marine biologist is quoted in that article saying: “You would have to come up with a rationale why [abyssal gigantism on Europa] couldn’t happen, and I can’t do that.”
Before you or I let our imaginations swim wild, I should note that that article from Hakai Magazine was the one and only source I could find on this specific combination of topics: abyssal gigantism and life on Europa. So maybe take all of this with a grain of salt (preferably a grain of Europan sea salt). But… well, I’ll put it to you this way: if someone were to write a story about a NASA submarine being attacked by sea monsters, that story would seem plausible to me.
Planet Pailly 
Especially great artwork to illustrate this post 🙂
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Thanks! It was a fun one to draw!
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We won’t know until we get there.
We always think in terms of carbon life forms, but what if the life forms there were something different? And what if they were giants…?
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That’s true, we won’t. But Europa has (or seems to have) the same chemical ingredients for life that we have here on Earth, so life there shouldn’t be so different from life here. For comparison, look at Titan, where life would have a very different set of chemical ingredients to work with and, therefore, would have to develop along a different path (assuming it develops at all).
But yeah, we won’t really know until we get there. And even then, breaking through Europa’s icy crust will be difficult. So it will still be a long time before any NASA submarines get attacked by sea monsters.
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But when that happens, you’ll be ready – and say I told you so!
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Very cool artwork!
If you haven’t seen it yet, I recommend the movie Europa Report. I recall it being reasonably scientifically accurate, albeit perhaps improbable.
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I have seen Europa Report! The last five minutes of that movie are amazing!
The only thing that really struck me as implausible, to the point that it kind of broke my suspension of disbelief, was that Europa’s ice layer seemed to be implausibly thin. Thin enough that light could shine through it, as I recall.
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A fascinating idea, James! Maybe those giant things with tentacles ARE lurking down there after all! Write it!
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I really, really, really want to do a story set on Europa. And I really want the title is be something like “Walking on Thin Ice.” But that story idea is still missing something, and I have a lot of other projects I need to focus on first. Someday, though, I will write that Europa story.
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Aww I was really hoping for something like marine worms. No hope at all for simple, multi-cellular organisms like that?
I guess a problem might be that Europa will most likely lack the rich, bacterial mats that helped the evolution of multi-cellular lifeforms on Earth?
In any case, interesting article! Just stumbled on your blog and currently reading.
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Thanks for visiting!
I’m no expert, but I’d assume Europa would have to have smaller and intermediate size creatures as well as giants. Though what counts as a smaller or intermediate size might not be the same on Europa as it is on Earth.
And of course all of this assumes that Europa has life at all, which we do not yet know for certain.
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