Science, Technology, and Society LET REVIEWER
General Education
Lesson 3: Eight Levels of Taxonomy
Taxonomy is the science of classifying and naming organisms. With millions of different species of organisms on Earth, scientists need a system to organize them and give them names. Taxonomy provides this system.
The Eight Levels of Taxonomic Classification
Scientists classify all organisms into eight different levels, from the broadest category to the most specific. Each level gets more specific, narrowing down the organism's identity.
"Dogs Keep Pets Clean Or Fleas Get Spread."
Dogs = Domain
Keep = Kingdom
Pets = Phylum
Clean = Class
Or = Order
Fleas = Family
Get = Genus
Spread = Species
The Eight Levels Explained
Domain
The broadest category. It divides all life into three main groups based on cell type and structure.
The three domains:
- Bacteria (prokaryotic cells)
- Archaebacteria (prokaryotic cells)
- Eukarya (eukaryotic cells)
Domain is the biggest group. It divides all life into three super-groups based on how their cells are structured.
Kingdom
 |
| Image from Britannica Kids |
The second level. It divides organisms into major groups based on how they get energy and their general characteristics.
Major kingdoms:
- Bacteria (one-celled prokaryotes)
- Archaebacteria (one-celled prokaryotes in extreme environments)
- Protista (mostly one-celled eukaryotes)
- Fungi (organisms like mushrooms and yeast)
- Plantae (plants)
- Animalia (animals)
Kingdom is a big group of organisms that are similar in major ways.
Phylum (plural: Phyla)
The third level. It groups organisms based on major structural features.
Examples:
- Chordata (animals with a backbone or notochord)
- Arthropoda (animals with joints and exoskeletons, like insects)
- Mollusca (soft-bodied animals, like snails and squid)
Phylum groups organisms by major body features.
Class
The fourth level. It groups organisms more specifically based on characteristics.
Examples:
- Mammalia (animals that have hair and produce milk)
- Aves (birds)
- Reptilia (reptiles)
Class divides organisms into smaller groups with more specific shared features.
Order
The fifth level. It groups organisms based on more detailed characteristics.
Examples:
- Carnivora (meat-eating mammals)
- Primates (humans, apes, monkeys)
Order divides organisms into even more specific groups.
Family
The sixth level. It groups organisms that are quite similar to each other.
Examples:
- Felidae (cats — lions, tigers, house cats)
- Canidae (dogs — wolves, dogs, foxes)
- Hominidae (great apes — humans, chimpanzees, gorillas)
Family groups organisms that are quite closely related.
Genus (plural: genera)
The seventh level. It groups organisms that are very closely related and share many characteristics.
Examples:
- Homo (humans and human-like ancestors)
- Canis (wolves, dogs, jackals)
- Felis (small cats like house cats and wildcats)
Genus groups organisms that are very similar and closely related.
Species (Most Specific)
The most specific level. A species is a group of organisms that can reproduce together and produce fertile offspring.
Examples:
- Homo sapiens (humans)
- Canis lupus (gray wolf)
- Felis catus (domestic house cat)
Species is the most specific group. Members of the same species can reproduce together.
Scientific Names (Binomial Nomenclature)
When scientists name organisms, they use a special system called binomial nomenclature, which was created by Carolus Linnaeus.
Binomial Nomenclature: Uses two parts; the genus name and the species name.
Format: Genus species
Example: Humans are named Homo sapiens
Homo = Genus (humans and human-like ancestors)
sapiens = Species (wise or intelligent)
Another example: The common house cat is named Felis catus
Felis = Genus (small cats)
catus = Species (cat)
Rules:
- The genus name is capitalized
- The species name is lowercase
- Both are usually written in italics or underlined
Every organism has a two-part scientific name: genus (like a last name) and species (like a first name).
Carolus Linnaeus: The Father of Modern Taxonomy
 |
| Image from The Guardian |
Carolus Linnaeus (1707–1778) was a Swedish naturalist and scientist. Linnaeus created the system of classifying organisms that we still use today. He proposed binomial nomenclature, the system of giving every organism a two-part scientific name.
Before Linnaeus, organisms did not have a standard naming system. Different people called the same organism by different names, which was confusing. Linnaeus created a universal system that allows scientists all over the world to use the same names and classification system.
Eight levels of taxonomy Quiz: click here
“I will pass the board exam. I will be a Licensed Professional Teacher. I believe in myself and my hard work. Write your name in the comments with LPT beside it to manifest”
Example: Juan Cruz, LPT
If you don’t claim it, you lose it
