Classification
Classification is grouping similar things together.
Scientists classify living things into groups, so that organisms are easier to study.
Aristotle was the first scientist to classify organisms based on their movement. He organized them into three groups: those that fly, those that swim and those that walk, crawl or run. He found that organisms grouped together were different in many other ways. So he divided each group into subgroups.
Linnaeus expanded on Aristotle’s idea and wrote down the description of the organisms. He devised a naming system for the organisms: Binomial nomenclature (Two part name). The first part of an organism’s scientific name is the Genus. The second part of the scientific name is the species.
When Linnaeus developed his classification system people thought species never change. The theory of evolution changed the outlook of the biologists. They understood that organisms are similar because they have share a common ancestor, thus share an evolutionary history. Today’s system of classification considers the history of a species when classifying the species.
Today’s classification system has seven levels to classify an organism.
Kingdom: Broadest Level
Phylum: consists of different classes
Class: different order
Order: different families
Family: different Genus
Genus: different species
Species: similar organisms that can mate and produce fertile offspring.
The more classification levels the two organisms share, the more characteristics they have in common.
Identification
To identify an organism, one can use a field guide, a book with illustrations that highlight differences between similar organisms. Another tool is to use a taxonomic key, a series of paired statements that describe the physical characteristics of different organisms.
Today, the classification system includes six kingdoms.
Archaebacteria / Unicellular / Both / Prokarotes / Ancient bacteria, live in extreme conditions
Eubacteria / Unicellular / Both / Prokaryotes / Live in normal conditions
Protists / Both / Both / Eukaryotes / Called“Odds and Ends” because organisms are very different from one another.
Fungi / Both / Heterotrphs / Eukaryotes / Reproduce through spores
Plants / Multicellular / Autotrophs / Eukaryotes / Feed almost all the heterotrophs
Animals / Multicellular / Heterotrophs / Eukaryotes / Have different adaptations. Found in diverse environments.
Questions
1: What does an organism’s scientific name consists of?
2: Why is the Protist kingdom sometimes called the “Odds and “ends” kingdom?
3: Which kingdom only includes multicellular heterotrophs?
4: Which kingdoms only include Prokaryotes?
5: Which kingdoms include both unicellular and multicellular organisms?
6: What is binomial nomenclature?