Taxonomy (not taxidermy, the business of stuffing animals) is the science of classifying organisms both extinct and extant (still living). Systematics includes any study that arranges these organisms into a sort of "family tree" showing all of their relations to one another. Phylogeny is the study of the evolution of a particular organism or group. Taxonomy, systematics, and phylogeny are necessary fields for all biologists to be acquainted with, as no matter what they specialize in, they can benefit from knowing what other organisms their creature of study is descended from or closely related to. So how does taxonomy work?
First, we should look at today's main classification levels (also known as "taxa") in systematics, and some of the commonly known groups that belong to them. Each level, or "taxon" (plural "taxa"), contains anywhere from a small handful to a large multitude of classification titles for the organisms that belong within it. Let's take a look at the different major taxa, ordered from large to small and with some classification examples shown in each.
1. Domain (plural "Domains")
The domains are Eukarya, Bacteria, and Archaea.
Humans are "eukaryotes," part of Domain Eukarya! At this level, we're classified with organisms made up of single cells.
2. Kingdom (plural "Kingdoms")
The kingdoms are Animalia, Plantae, Fungi, Protista, Bacteria, and Archaea.
We know that humans classify as animals, so we fall within Kingdom Animalia.
3. Phylum (plural "Phyla")
These become numerous very fast because there are many phyla in the various kingdoms. The same pattern of rapid expansion occurs through the ranks of Class, Order, Family, Genus, and Species, so to simplify things we'll continue using the example of a human.
Within Kingdom Animalia: Phylum Chordata
4. Class (plural "classes")
Within Phylum Chordata: Class Mammalia
5. Order (plural "orders")
Within Class Mammalia: Order Primates
6. Family (plural "families")
Within Order Primates: Family Hominidae
7. Genus (plural "genera")
Within Family Hominidae: Genus Homo
8. Species (plural "species")
Within Genus Homo: Species Homo sapiens
Each scientific name of a species follows a general rule of binomial nomenclature, meaning a "two-part name". Notice that for us humans, our genus name "Homo" and species name "sapiens" are combined to make one scientific name, Homo sapiens. We usually italicize the name, capitalizing the first letter of the genus name and leaving the species name in lowercase. We can abbreviate scientific names by only using the first letter of a species' genus in the scientific name--for example, H. sapiens--which simplifies reading or writing a repeated species' scientific name or the comparison of many species that can exist under a single genus. Our species is actually the only surviving species of our genus; the extant or still-living species in our family include ourselves, chimpanzees, gorillas, and orangutans.
Can I remember all of the taxonomic classifications assigned to every ocean creature? No way, and I doubt I could in my lifetime--but I'm learning as much as I can! Why? Once you have the main taxa memorized and begin learning the different groups and organisms that belong to each level, you'll start forming a cool understanding of whatever kind of organisms you're studying, from how they're related to how they evolved and what roles they often play in any ecosystem. Here's a mnemonic device (a memorable pattern) so you can remember the main taxa for a start! "Dear King Philip Came Over For Good Spaghetti." The first letter of each word corresponds to Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species. If you can remember the phrase and spend some time rehearsing the taxa that go with each word in the phrase, you'll have all eight taxa memorized in no time!
You may have noticed that the term "Bacteria" and "Archaea" appear at BOTH the Domain and Kingdom levels. Why the repeats of "Bacteria" and "Archaea"? To be perfectly honest, taxonomy gets a little messy sometimes, and scientists around the world sometimes disagree on various aspects within the current taxonomic system, such as where a single species goes or whether one phylum ought to be split into two phyla instead. Thankfully, this system is a lot cleaner and more agreed upon than it used to be! That's because scientists who specialize in the study of various aspects of living creatures, from their physiology, meaning physical characteristics, to their DNA and RNA, meaning their genetic code (the most essential thing that determines what an organism is), have made many great advancements that helped us better understand how organisms evolved and how they are related.
You may have seen other taxons than I've shown so far in this blog post. That's because the eight taxa I've shown here are generally considered the minimum, though the https://www.britannica.com/science/taxonomy/Ranks page gives a great example of the kinds of additional taxa you might see when dealing with an organism that is part of a more complex classification with added taxa to properly classify it:
Northern (Canadian Subarctic) Timber Wolf:
Kingdom Animalia | Subkingdom Metazoa | Phylum Chordata | Subphylum Vertebrata | Superclass Tetrapoda | Class Mammalia | Subclass Theria | Infraclass Eutheria | Cohort Ferungulata | Superorder Ferae | Order Carnivora | Suborder Fissipeda | Superfamily Canoidea | Family Canidae | Subfamily Caninae | Tribe (none described) | Genus Canis | Subgenus (none described) | Species Canis lupus (wolf) | Subspecies Canis lupus occidentalis
In the above example you see a trinomial scientific name. I did say the rule was only a general one! The exception to the rule occurs when the taxonomy assigned to an animal gets more specific, such as for Canis lupus familiaris, the domestic dog.
Want to learn more about how ocean creatures are classified? Check out my "Main Classifications" blog category for more coming soon after this blog post!
Resources:
Comments