Classification of OrganismsChapter 18

What is an Organism?What is an Organism?

An organism is generally referred to An organism is generally referred to any living thing. More specifically any any living thing. More specifically any thing that has “cells”. thing that has “cells”.

This includes the smallest of This includes the smallest of organisms,organisms,the single celled bacteria, all the way the single celled bacteria, all the way to theto thelargest redwood tree or Blue Whale.largest redwood tree or Blue Whale.

Why Classify?

Biologists use classification to organize living things into groups so that the organisms are easier to study.

In the following few slides, you will In the following few slides, you will findfind14 different organisms, each of them 14 different organisms, each of them labeled with a letter. labeled with a letter.

In your groups, write down two main In your groups, write down two main classification (example red/green).classification (example red/green).

Then place the corresponding letters Then place the corresponding letters underunderthe correct classification.the correct classification.

The Classification Game!!The Classification Game!!

Divide into groups of 3 Divide into groups of 3 or 4or 4

For ExampleFor Example

These organisms have beenThese organisms have beenclassified by their color.classified by their color.

RedRedGreenGreen

AREARE

YOUYOU

READY!READY!

I

B

H

L M

A D

F

C

N

G

E

K

J

One Possible SolutionOne Possible Solution

PlantsPlants AnimalsAnimals

A

B

C

D

E

F

G

H

I

J

K

L

M

N

????????

Did You Have Problems??Did You Have Problems??

There were actually several different ways There were actually several different ways to goto goabout classifying these 14 organisms. You about classifying these 14 organisms. You might might have done color, shape, size, number of have done color, shape, size, number of legs… the possibilities are endless. You legs… the possibilities are endless. You might have encountered one or two that might have encountered one or two that really did not fit into either of your two really did not fit into either of your two classifications, what should you do when classifications, what should you do when this happens? Make a new classification of this happens? Make a new classification of course! And this is what scientist have course! And this is what scientist have done as well through the years.done as well through the years.

Our modern classification system originated withOur modern classification system originated withtwo main classifications, plants and animals. Overtwo main classifications, plants and animals. Overthe years, scientist came up with certain “plants” the years, scientist came up with certain “plants” that really did not act like plants, they couldn’t that really did not act like plants, they couldn’t make their own food. So the kingdom Fungi wasmake their own food. So the kingdom Fungi wasformed. formed.

When microscopes were invented, When microscopes were invented, scientist discovered new single celled scientist discovered new single celled organisms. Some were animal-like, some organisms. Some were animal-like, some were plant like and some were both. were plant like and some were both.

This lead to the creation of the Kingdom This lead to the creation of the Kingdom Protista.Protista.

As the microscope improved, scientist As the microscope improved, scientist discovered that many of the single celleddiscovered that many of the single celledorganisms were quite different. Some of themorganisms were quite different. Some of themhad a nucleus and others did not. This leadhad a nucleus and others did not. This leadto the Kingdom Monera, the kingdom of the to the Kingdom Monera, the kingdom of the most simplistic organisms, Bacteria.most simplistic organisms, Bacteria.

Taxonomy-The study of how living things are classified

Asistotle – he had the first classification system that group animal according to how the moved or where they lived.

Swim Fly Walk /crawl

He also had subgroups for organisms that shared other characteristics

Carolus Linnaeus- Swedish – He placed organisms in groups according to observable features and physical characteristics.

Linnaeus’s Naming System

Linnaeus had a two name system called

Felis concolor is the scientific name for a puma.

Is the genus name- it is written first and is always capitalized

Is the species name – it is written second and is always lower case

Linnaeus used the Latin language Linnaeus used the Latin language because that was the language thatbecause that was the language thatwas dominate around the world at was dominate around the world at that time. This is why even today that time. This is why even today organism’s scientific names are always organism’s scientific names are always in Latin.in Latin.

Along with the two major Kingdoms,Along with the two major Kingdoms,PlantPlant and and AnimalAnimal, Linnaeus came up, Linnaeus came upwith several sub-classifications for thosewith several sub-classifications for thosekingdoms. They are: kingdoms. They are: Kingdom, PhylumKingdom, Phylum, , Class, Order Family, Genus,Class, Order Family, Genus, and and SpeciesSpecies. .

What Kingdom are you in?What Kingdom are you in?

What phylum are you in? Why?What phylum are you in? Why?

Levels of classification

Kingdom Phylum

Class

Order

Family

Genus

Species

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The Human SpeciesThe Human Species

Kingdom:Kingdom:Phylum:Phylum:Class:Class:Order:Order:Family:Family:Genus:Genus:Species:Species:

Animalia (Animal in Latin)Animalia (Animal in Latin)Chordata (Spinal Cord)Chordata (Spinal Cord)

Mammalia (have mammary glands)Mammalia (have mammary glands)Primates (two mammary glands)Primates (two mammary glands)Hominoidea (bipedalism)Hominoidea (bipedalism)HomoHomoSapienSapien

When you refer to an organismWhen you refer to an organismscientifically, you always use the scientifically, you always use the genus and the specie names.genus and the specie names.Therefore, the human species wouldTherefore, the human species wouldbe referred to as:be referred to as:

Homo sapienHomo sapien

Recognizing Species

Biologists usually define species based on appearance and structure

Biological species- group of actually or potentially interbreeding natural populations, reproductively isolated from other such groups

Hybrids can be made between two species

Evolutionary History

Convergent evolution- organisms evolve similar features independently Example: anteaters- long, sticky tongue; few

teeth; large salivary glands

Evolutionary History

Analogous characters- similar features of organisms that evolve independently

Phylogeny- evolutionary history of a species

Cladogram

Cladogram- diagram based on patterns of shared, derived traits that shows the evolutionary relationships among groups of organisms

Cladogram

Differences in morphological, physiological, molecular, and behavioral level between organisms

New derived characters will show up on the cladogram as groups evolve

ConclusionConclusion

The classification system for organismsThe classification system for organismshave been around for a long time. It hashave been around for a long time. It hasendured several changes and is quiteendured several changes and is quitecomplex. Without it modern biology couldcomplex. Without it modern biology couldnot exist, much in the same way thatnot exist, much in the same way thata grocery store would go out of businessa grocery store would go out of businessif it did not have a classification system.if it did not have a classification system.