CLASSIFICATION

Similarities and Differences

TEKS 8A: Students will…

define taxonomy and recognize the

importance of a standard system to the

scientific community

8B: Students will…

categorize organisms using a hierarchical

classification system based on similarities

and differences

8C: Students will…

compare the characteristics of taxonomic

groups

CLADOGRAMS AND

DICHOTOMOUS KEYS

CLADOGRAMS AND DICHOTOMOUS KEYS

Cladograms are used to show the evolutionary

history of an organism and its relationship to other

organisms

Similar to a family tree you can trace an

organism’s history through time, and see how closely

related they are to other organisms

CLADOGRAMS AND DICHOTOMOUS KEYS

How can we place newly discovered organisms into their correct

spot on a cladogram?

Nodes of the cladogram are areas where organisms diverged in

their evolution

Speciation

Therefore, a cladogram is nothing but a series of choices

o A dichotomous key is used

to help identify organisms

Based on a series of two

choices

o You read both choices, which

will lead you to another

set of choices until the

organism is identified

DICHOTOMOUS KEY EXAMPLE

DICHOTOMOUS KEY EXAMPLE

CLADOGRAMS AND DICHOTOMOUS KEYS

CLADOGRAMS AND DICHOTOMOUS KEYS

CLADOGRAMS AND DICHOTOMOUS KEYS

Example

1a: Four limbs– Go to 2

1b: Does not have four limbs– Fish

2a: Covered skin – Go to 3

2b: Skin not covered– Amphibian

3a: Birth via amniotic eggs – Go to 4

3b: Live birth – Mammals

4a: Feathers – Aves (birds)

4b: No feathers – Reptile

CLASSES OF ANIMALS

Fish (vertebrate)

No limbs (arms or legs)

Covered in scales

Lay unshelled eggs

Amphibians (vertebrate)

Four limbs

Thin, uncovered skin

Lay unshelled eggs

Mammals (vertebrate)

Four limbs

Covered skin (in hair)

Give birth to live young

Reptiles (vertebrate)

Four limbs

Covered skin (in scales)

Lay amniotic eggs

Aves/Birds (vertebrate)

Four limbs

Covered skin (in feathers)

Lay amniotic eggs

Insects (invertebrate)

Six limbs

Exoskeleton

Lay eggs

Antenna & compound eyes

CLASSES OF ANIMALS

HOW WE CLASSIFY

History and Naming

WHY DO WE CLASSIFY?

https://vimeo.com/19796663 (0:00-1:33)

Scientists currently estimate that there are

approximately 8.7 million (+/– 1.3 million) organisms

on the planet today

A study published by PLoS Biology says 86% of all land

species and 91% of marine species have yet to be

discovered, described, and catalogued

VOCABULARY

Species: a group of organisms that can

interbreed and produce fertile offspring

Taxonomy: the science of classification

Binomial Nomenclature: a two-part scientific

name consisting of the organisms genus and

species

HISTORY OF CLASSIFICATION

Aristotle classified organisms into two categories –

plants and animals

However, this system did not allow for evolutionary

relationships or organisms that did not fit into

either the plant or animal category

In the 1700’s, a new system was created by Carolus

Linneaus

Modern classification still

uses Linneaus’s system, but

has been updated to show

evolutionary relationships

CAROLUS LINNAEUS

Created binomial nomenclature

Organisms categorized into taxa – groups based on

specific criteria and shared characteristics

MODERN CLASSIFICATION

Today taxonomists classify organisms based on

Physical similarities

Genetic similarities

Biochemical similarities

Behavioral similarities

There are eight classification groups

Domain (3) (Hemisphere)

Kingdom (6) (Continent)

Phylum (54) (Country)

Class (State)

Order (County)

Family (City)

Genus (Street)

Species (~8.7 million) (House #)

MNEMONIC DEVICE

Domain Dear

Kingdom King

Phylum Philip

Class Cried

Order Out

Family For

Genus Good

Species Shoes

CLASSIFICATION LEVELS

RED FOX CLASSIFICATION

GRIZZLY BEAR CLASSIFICATION

CLASSIFICATION FOR HUMANS

CLASSIFICATION COMPARISON

NAMING ORGANISMS

Scientists name organisms in order to

assist in clarity and organization

Why not use common names?

Common names can vary from location to location for

the same organism. Ex: cougars, pumas, mountain

lions, and panthers are all the same organism

Common names can be misleading. Ex: a starfish is

not a fish, a mountain goat is not a goat, a guinea pig is

not a pig, and a killer whale is not a whale

NAMING ORGANISMS

There is only ONE scientific name for an

organism

Organism’s scientific name = Genus species

The correct way to write a scientific name

Genus capitalized and species lowercase

The whole name should be in italics or underlined

DOMAIN AND KINGDOM

DESCRIPTIONS

DOMAINS AND KINGDOMS

THREE DOMAINS AND SIX KINGDOMS

Each has a set of characteristics that bind the

organisms in the group together

These characteristics are not hard-and-fast ‘rules’,

but more like guidelines

THREE DOMAINS AND SIX KINGDOMS

1. Archaea – contains one kingdom (archaea)

2. Bacteria – contains one kingdom (eubacteria)

3. Eukaryea – contains four kingdoms (protists,

fungi, plants, and animals)

DOMAIN ARCHAEA

Kingdom Archaea

Ancient prokaryotes

Unicellular

Cell walls

Autotrophic OR heterotrophic

Called extremophiles because they live in extreme

environments

Methanogens – make methane gas

Thermophile – love heat (found in hot springs)

Halophiles – love salt

Decomposers – break

down dead/decaying

organisms

DOMAIN BACTERIA

Kingdom Eubacteria

Prokaryotic

Unicellular

Cell walls made of peptidoglycan

Some are aerobic, some are anaerobic

Most are heterotrophic, but a few are autotrophic

Decomposers – break down dead/decaying organisms

More abundant than any other organism

DOMAIN EUKARYA

All are eukaryotic

Contains 4 kingdoms: protista, fungi, plantae,

animalia

DOMAIN EUKARYA

Protista

Eukaryotic

Some are unicellular and some are multi-cellular

Some are autotrophic (make their own food), but

some heterotrophic

Some have cell walls, others do not

Known as the “odds-and-ends” kingdom since these

are the organisms that simply do not fit anywhere

else

DOMAIN EUKARYA

Fungi

Eukaryotic

Multi-cellular (except yeast)

Have cell walls are made of chitin

Heterotrophic

Decomposers

DOMAIN EUKARYA

Plantae

Eukaryotic

Multicellular

Has a large central vacuole,

chloroplasts, and cell walls (peptidoglycan)

Autotrophic – can make their own food using

energy from the sun

FYI: many organisms depend on plants because of

their ability to make food

DOMAIN EUKARYA

Animalia

Eukaryotic

Multi-cellular

No cell walls

Heterotrophic – cannot make their own food, so they

must eat plants, hunt, filter feed, or scavenge for food