How do we organize living things?
Updated: May 16, 2020
The simple answer: taxonomy!
You have probably seen the scientific name (also called the Latin name) that is unique to all species. Swedish scientist Carl Linnaeus founded the method of naming nearly 300 years ago, and it has remained the accepted system for officially naming a species. He chose Latin as the basis, because Latin was considered a scholarly language at the time (Greek is sometimes used too).
It is helpful to have a standard language for naming species that does not favor a common language in the world. If an English-speaking scientist named the species in English, it might not translate well across the world. If a Chinese-speaking researcher named it in Chinese, we might have difficulty even recognizing the characters used.
A so-called “dead language” like Latin puts everyone on equal footing, and does not include or exclude any particular group.
It is sometimes referred to as binomial nomenclature, which is just a fancy way of saying that the species are identified by two (binomial) names (nomenclature).
Why is this important?
Take the apple as an example. You and I would look at it and see an apple. An Italian-speaking person sees una mela; a French person might see une pomme; and our Spanish-speaking friends would call it una manzana.
But an apple scientist could read Malus domestica and know exactly what it is.
Everywhere in the world, in any scientific paper, Malus domestica is the same thing.
No matter if it is called apple, mela, pomme, or manzana at the local grocery store.
The first part of the name Malus is the Genus and the second part domestica is the species.
What does this mean?
It is all about the level of classification. That is to say, it is about how specific you want to be. Only one species in the entire world has that species name, but several may share the Genus, and many more are added for every level upward.
Let’s use the honeybee as another example.
Taxonomy is a kind of ranking of the categories that the organism fits into. Here’s how it usually breaks down, from the broadest category with millions of species all the way down to the one species identifying name:
Domain- is it a eukaryote (cells have a nucleus like plants and animals), prokaryote (cells do not have a nucleus- basically bacteria), or archaea (superhero “extremophile” bacteria who also do not have a nucleus)?
Kingdom- in the eukaryotes, is it a plant, animal, fungus, or protist?
Phylum- in the animals, does it have a spine (vertebrate) or not (invertebrate)?
There are 36 phyla in the Animal Kingdom, and only one of them is animals with a backbone!
So it already gets a bit complicated, as the invertebrates are divided into worms, molluscs, jellyfish, arthropods (basically insects, arachnids, myriapods, and crustaceans), and so much more!
And it only gets more complicated from there. Taxonomists have a lot of work to do, and a lot of details to pay attention to. The next categories are:
Class
Order
Family
Genus
Species
Genus and species are always italicized, with Genus capitalized and species lowercase:
Genus species
Sometimes scientists break these down even further into subclasses, suborders, subspecies, etc., but the main categories are perfectly suitable for our purposes.
The good news is, for every species we know of, this work has already been done. All you have to do is look it up!
Back to our honeybee, which was named by Linnaeus himself in 1761. These are the taxonomic levels that classify it and, except for the very last category, all of its relatives.
Domain: Eukarya
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Apidae
Genus: Apis
Species: mellifera
Anywhere in the world, Apis mellifera means honey bee.
It’s a Eukaryote, so the cells have a nucleus.
It is an Animal, so its cells do not have a cell wall.
It is an Arthropod, so it has an exoskeleton and jointed legs.
It is an Insect, so it has three pairs of legs, antennae, and three body segments.
It is a Hymenopteran, so some of them have wings, they have compound eyes, chewing mouthparts, and many of them have a stinger.
As part of the Family Apidae, they are typically social and important pollinators. There are over 5,700 bees in this group!
Genus Apis narrows it down to about 7 living species of honeybees
And lastly, species mellifera gives us the one and only European honeybee- the hero that provides not only honey, but many of our favorite fruits, vegetables, and flowers.
Challenge: Try it yourself!
Take a picture, find a picture online, or pick your favorite animal, plant, or fungus (some people really like mushrooms!)
Classify it for us and share what you find! Was it difficult to find the information? Do scientists have any problem fitting your species into one category?
Taxonomy is a surprisingly fluid science. Many times you have to revise your understanding, or even completely rename a species when you find new species or discover new information.