Katy Perry catches otters, but frequently gets seasick.
Easy enough to remember, right? It’s a mnemonic device I use to remember the principle taxonomic ranks: Kingdom, Phylum, Class, Order, Family, Genus, Species. I came up with it myself. There are others, but they’re not as good as mine. I think in school they had us use something about kings playing chess, but it was super lame.
You can also use Kungfu Panda Can One-shot a Furious Gut Slap. Wait, is Kung Fu two words?
Or “Kill the Penguin,” Confucious Orders, “Fishy Good Snack.”
But my point here is I realize I’ve long ago ingrained the function and use of Systematics, which is essentially the classification of living things based on (ideally, anyway) evolutionary history and, by extension, genetic relatedness. Taxonomics is the field of putting all those known and identified species into discrete categories and subcategories, ranked by relatedness like a family tree. It’s basic bio, so I never bothered to explain it. But any time I use a term like Family or Class with a capital letter, I’m using an official term. I’m referring to a taxonomic rank.
And I realize I should explain this a little. So here’s a quick rundown of what I mean by these words, and how other biologists will also use them. Starting at the top:
General and broad. There are at least 5 discrete Kingdoms, and as many as 8 depending on who you ask. The obvious and most stable ones are Animalia (animals), Plantae (plants), and Fungi (fungi…you could probably guess). These ones are easy to define, but after that it gets tricky. Most algae are in a Kingdom called Protista, but this also includes some things that aren’t readily algae-ish. And sometimes they get split up into another Kingdom called Cyanobacteria. Not to be confused with an obsolete Kingdom Bacteria, now referred to as Archaea, or split into more Kingdoms…and you see where I’m going with this. Little single-celled organisms (“microbes” to those at home) are constantly shifted around and recategorized based on who’s trying to publish a textbook.
Essentially, organisms in the same Kingdom share the same fundamental life strategies: they all eat the same nutrients, breath the same gases, and reproduce the same way. Animalia, Plantae, and Fungi are multicellular. Protists can be. Anything else is single-celled and falls into what I think of as a grab bag of microbes because I don’t do microbiology and can get away with saying things like that.
(I should also mention that a lot of this has changed since I was last in school, and may already be out of date. Either way, I’m going to focus Animalia from now on.)
I like to think of Phyla (yay for Greek plurals) as different kinds of toys in a playroom. You’ve got your box of Legos, your K’nex, your Tinker Toys, and your Play Doh. Now you can build whatever you want with them, and there’s quite a variety of creative design space within any material, but you’re choice of material will play a pretty big part in determining the basic shape and function of what you make. And the toys probably won’t play nice with each other.
An octopus is definitely not a snail, but both are squishy and slimy. Both are in the Phylum Mollusca. Lobsters and cockroaches, both Arthropoda, have hard shells with joints and knobby bits. And a whale and a frog both have a skeleton that look so similar you’d accuse some primordial creator god of cheating. Or at least phoning it in. But the fact is, the Phylum Chordata includes all vertebrates with a backbone or even a primitive spinal notochord, and probably comprises 90% of what you think of when you hear the word “animal.”
Maybe the toy analogy works better here. Animals in the same Class (Class-mates? I’m trying it out) are clearly made out of the same material, even to the average layperson. This is also where taxa take on common, vernacular names. Mammalia? Mammals. Warm and furry. Aves? Birds. Flappy and feathery. Reptilia? Reptiles. Scales. Simple.
But also not. Because this is also where things start to get blurry. After all, evolution is a constantly shifting force and genetics are saucy little numbers who don’t sit still for more than a few generations. It can be hard to pin down just what fits into which category, and if there’s one thing scientists love doing it’s arguing with each other about what to call things. So depending on the clade (or “evolutionary lineage”) you might get extras like “infra-this” and “sub-that.” So if you hear anything different or someone tells you this is wrong, don’t worry about it, just nod your head and agree, especially if they have several acronyms after their name.
Now things start to get really tricky, but bear with me. An Order is like a guild. Or maybe a graduating class. They’re a bunch of like-minded characters who share a general background, life history, and while they don’t always get along they can probably still mingle at a 10th anniversary reunion together long enough to swap stories and exchange business cards. Make small talk.
Not all animals in Carnivora strictly eat meat, but the coolest ones do so the Order is named after them. But everyone in Carnivora, from bears to wolves to seals, has a good set of chompers. And rodents of Rodentia have ever-growing, red-tinged incisors. Butterflies and moths are all Lepidoptera, easily distinguished from Hymenoptera which is ants, bees, and wasps.
Now the patterns emerge. The similarities are obvious. Vernacular names abound, and most people would subconsciously group these together even without prior knowledge. Also, I think I’ve talked about this before.
You got your Canidae (canines), your Felidae (felines), your Ursidae (bears), and Procyonidae (raccoons and kin, yeah I’ve definitely talked about this before). Fun fact: all Families, regardless of other taxa, all end in –dae. Subfamilies end in –nae, but these are stupid and I don’t like them and besides they’re too complicated to cover here.
I better wrap this up: by the time you get to Genera, organisms can easily be mistaken for each other. They can probably crossbreed but not very well. Evolutionarilty, they diverged within recent history (relatively, that is). Think dogs vs wolves, Genus Canis. But don’t disregard the distinction. Consider Homo sapiens vs Homo neanderthalis.
Oh, and you’re supposed to start italicizing names at this point. Don’t ask me why.
Ah, here we are. The discrete organism. The basic unit of biological diversity. The legal term, for purposes of endangered species.
Each species can be referred to by binomial nomenclature (just Genus + species) since no two species share the same combo. But the full taxonomic name of, say, your domestic dog would look like Animalia Chordata Mammalia Carnivora Canidae Canis familiaris. Kingdom, Phylum, Class, Order, Family, Genus, Species.
Katy Perry Catches Otters, but Frequently Gets Seasick.
Although, shoot, now that I’m fact-checking this it looks like most people use “Domain” as an extra level above Kingdom. What the hell? Wait, what if I make it a question? Does Katy Perry catch otters?
Please don’t sue me. Or cite me.