Classification of Living Things
What is Classification? The arranging of organisms into groups according to how they are alike = classification. Taxonomy = The branch of Biology that involves identifying, classifying, and naming organisms. Scientists who study Taxonomy are Taxonomists.
Early Classification Aristotle, a Greek philosopher, developed the first widely accepted system of classification. Classified organisms into two main groups and further broke them down by observable traits: Plants Herbs Shrubs Trees Animals Swam Flew Walked
Aristotle's Animal Classification System Question: Which animas have no red blood, soft bodies and a shell? Does this system work for all organisms on the planet? Shellfish Not even close!
A New Approach Aristotle’s system lasted for centuries. But as new organisms were discovered the system wasn’t allowing for their classification. Carolus Linnaeus, 18th century, developed a new method of classification. based on the physical and structural similarities. His system of classifying and naming organisms survives to this day. Movie: Carl Linnaeus 3:58 min
Basis for Classification Modern classification is based on the idea that organisms who share a common ancestor are related and also share a similar evolutionary history. Evidence: Structural Similarities Evolutionary Relationships Genetic Similarities
Structural Similarities If two organisms have similar structures, they likely evolved from a common ancestor. Who is the most structurally similar to each other? Domestic Dog & Wolf Who is the least structurally similar to each other? Cat to the Domestic Dog & Wolf
Evolutionary Similarities The more recent two organisms split from a common ancestor the closer related they are. Which two organisms have the closest ancestor? What level of classification do ONLY these two share? Which organisms have the most distant ancestor? do they share? Domestic dog & wolf Genus - Canis Cat to Dog & Wolf Order - Carnivora
Genetic Similarities Chromosomes (X)– The number and structure of chromosomes also indicate a common ancestor. 38 64 60 78 78
Levels of Classification Classification is based on groups of organisms that all have similar characteristics but can be broken down to the individual by a specific characteristics within that group. – hierarchial system. (Largest most general grouping) Your LAST NAME, FIRST NAME (smallest and most specific)
5 Kingdoms Monera – primitive cell structure lacking a nuclear membrane. Ex. Bacteria & Blue-green Algae Protista – Has membrane bound organelles but unicellular. Ex. Protozoa & Algae Fungi – Has membrane bound organelles but doesn’t ingest food, instead absorbs nutrients. Ex. Molds, mushrooms & Yeast Plant – photosynthetic multicellular organisms. Ex. Plants Animal – Multicellular and ingests their food Ex. Animals
Domains All life falls within three Domains, the highest level of organization.
Understanding Levels The Sea Star, Abert Squirrel and Giant Panda all share this level. Ursidae is this level of classification? What level does the Grizzly occupy all by itself? Kingdom Anamilia Family Species – Ursus arctos
Naming Organisms Common names differ depending on where you happen to be: Florida panther = puma, cougar, mountain lion or panther. Linnaeus used a two-part (Genus and Species) Greek or Latin name to create unique individual names for each organism – Binomial Nomenclature Binomial = “two names” Nomenclature = “naming”
Naming Organisms Florida Panther = Felis Concolor Always written in itallics Felis = genus always capitalized! concolor = species always lower case!
Dichotomous Key Dichotomous = “two parts” Dichotomous Keys are made up of several pairs of opposing statements based on observable characteristics. Choose the statement that best describes the organism and move on to the next set of statements. When you can’t move any further through a pairing you should be at the name of the organism you’re identifying.
Dichotomous Key Eagle Jacana Cormorant Kingfisher