Protists: they make no sense

I don’t like having to label things. I don’t mean an actual sticker label–I find that oddly satisfying…

But I don’t like having to take a complicated person or thing and slap a simplistic label on it, perhaps because I especially hate it when this happens to me.

But unfortunately for me, labeling and categorizing things (which should never be confused with actually understanding things) is not only part of human nature, but it’s a big part of biology.

Scientists are usually pretty good at cataloging the diversity of life.

But there are times that our human system for organizing and cataloging the diversity of life doesn’t work as well, and I, with my anti-label sentiment, take glee in it.

Meet the Protists.

Protists are eukaryotic–they have a nucleus, but they don’t fit into any of the other eukaryotic filing cabinets known as animals, plants, and fungi. If a creature with a nucleus isn’t any of those, it’s a protist. For this reason, Kingdom Protista is occasionally called the “junk drawer kingdom.”

Here are a few examples of protists:


Slime molds
Gigantor kelps
Can’t you see how they are all super closely related?

They’re not grouped based on what they are; they’re grouped based on what they’re not.

But it’s okay. Protists don’t mind. They are proud to be what they are–the weirdest kingdom of all. They actually represent the ancestors of all the more recognizable eukaryotes–plants, animals, and fungi. That’s why this kingdom is so very random: it’s evidence of the evolutionary tinkering that brought about modern multicellular life. Some protists are even referred to as “animal-like,” “plant-like,” and “fungus-like,” lowering scientists to the valley girl level.

Perhaps the most infamous protist of all is plasmodium, the protist that causes malaria. It’s mosquitos that spread the protists around, but the disease is caused by plasmodium. That jerkface.

Regarding classifying protists, never forget that our system of classifying and naming living things is just our human brains trying to make sense of a vast and complicated natural world that does not want to be made sense of. Translation: we try to place order over nature, but it doesn’t always fit quite right. Plants and animals fit into nice little boxes with all their similar traits, and bacteria are unmistakably bacteria. But protists… They laugh at our pathetic attempts to define them. So it’s not really that they make no sense, as the title of this post says, but rather that we can’t make sense of them. And that is why I love them.

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6 replies
  1. Psi Wavefunction
    Psi Wavefunction says:

    Loved your post, good ‘definition’ of protista if there is one =D I’d like to point out though that nowadays we don’t really categorise them as animal-like/plant-like/fungus-like, although even very recently those were widely used, largely because there was no other way to group them (the vast majority of total eukaryotic diversity, by the way). Now we’ve got molecular phylogenies and such, and while the kingdom is still a mess, the categories are a little more sensible and ‘mature’ than morphology alone. It turned out that those animal/plant/fungal resemblances were outright misleading: eg, fungal-like things got strewn all over the tree, as did plant-like and parasitic critters. Convergent evolution had a little too much fun with that group ;-)

    On the other hand, it’s not as chaotic and disorganised as it used to be, and is starting to make some sense in places. The algal chaos is greatly resolved by secondary and tertiary plastid endosymbioses (almost all plastids share a common primary endosymbiotic event, save for a couple weird ones), the vast diversity of shape and lifestyles within the smaller groups makes sense if you take in just how genetically diverse they are, and how tiny plants, animals and fungi are in comparison – after all, if a clam, a scorpion and a sea horse can look so different, it’s no surprise things go absolutely haywire for the rest of eukaryotes!

    Also RE a preceding post, it’s totally “neesh” and not “nitch”, unless you’re American =P (in Canada it tends to be the former, not just for snobby Brits ;p)


    Friendly neighbourhood protist freak

  2. Beatrice
    Beatrice says:

    I have officially been knowledge-bombed! Thanks so much for this very thoughtful comment, Psi. You’re my hero.

  3. Dharlette
    Dharlette says:

    I was under the impression that protists aren’t considered a kingdom anymore, and that instead of the old 5-kingdom system we’re running with 3 domains (Eukaryotes, Bacteria, and Archea) with many kingdoms in the Eukaryotes including multiple kingdoms of protists. “Protists” are kind of like “algae”: the term has no taxonomic meaning anymore.

  4. P
    P says:

    I don’t understand the irrational devotion to ranked Linnean hierarchies at all. Even well understood groups necessitate the invention of elaborate new ranks like “Infraorder” and such. Phylogenetic relationships are far more complex than the ranked system is suited to handle.

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