THE LINNAEAN

CLASSIFICATION

SYSTEM Pages 5-4 through 5-11

Linnaean Classification

Created by Carolus

Linnaeus in 1735

Swedish botanist

Created an organized

system to categorize

plants and animals

Two-name system =

binomial nomenclature

2

The Need for classification

Three reasons for classification:

It helps to identify relationships between organisms

It requires scientists to identify key characteristics of organisms

It helps to avoid confusion

Only one Latin name (Genus species)

Common names differ by culture & one species may have several common names

3

Classification Taxa

An organism’s scientific name represents two taxa:

Genus – a group of closely related organisms

Examples: house cats, lions, tigers, bobcats, mountain lions, & cheetahs are in the genus Felis

Species – written in lower-case

usually a group of organisms that can reproduce together

Organisms are identified by their genus and species

4

Seven main taxa

1. Kingdom =group of phyla

2. Phylum (division) = a group of classes

3. Class = group of related orders

4. Order = group of related families

5. Family = group of genera that share characteristics

6. Genus (genera) = group of closely related species

7. Species = Latin name for an individual organism

5

Determining Taxa

How organisms are classified

Anatomical features

Theoretical evolutionary relationships – genetics

Common Problems:

Some organisms don’t fit neatly into defined groups

Ex: ratfish

Solution:

Assigning superlevels – creates higher divisions

Assigning sublevels – creates lower divisions (subphyla)

6

Classification systems

Six-Kingdom system:

Kingdom Eubacteria

Kingdom Archaebacteria

Kingdom Protista

Kingdom Fungi

Kingdom Plantae

Kingdom Animalia

Three-Domain System

Domain Archaea

Domain Bacteria

Domain Eukarya

7

Prokaryotes

Important primary producers in

the ocean

Characteristics of Prokaryotes

Structurally simple

Lack chromosomes or a nucleus

(only have DNA or RNA)

No mitochondria or chloroplasts

Believed to be the oldest types

of organisms

8

Archaea & Bacteria

Includes Kingdoms Archaebacteria & Eubacteria

Most Archaebacteria are extremophiles

(live in mostly inhospitable environments)

Volcanic sulfur pools

Hydrothermal vents

Phylum Cyanophyta (Cyanophytes)

Eubacteria

Evolution of photosynthesis

Nitrogen fixation

Pigments contribute to the color of other organisms

9

Eukaryotes (Eukarya)

Includes Kingdoms Protista, Fungi, Plantae, & Animalia

Single-celled to multi-cellular

Cell specialization

10

Protists

The Kingdom Protista is made up of seven phyla:

Chlorophyta – green algae

Rhodophyta – red algae

Phaeophyta – brown algae

Dinophyta – dinoflagellates

Bacillariophyta – diatoms

Euglenophyta

Chrystophyta

11

Plants & Animals

Not many plant species can

survive in the ocean

Can’t cope with salinity

Marine animal groupings:

Invertebrates

Vertebrates

12

Animals

Invertebrates

Sponges

Cnidarians

Marine worms

Mollusks

Arthropods

Echonoderms

Chordates (vertebrates)

Reptiles, fish, birds, and mammals

No amphibian species in the ocean.

13

Quiz

1. What are the three reasons for classification?

2. What are the six kingdom names?

3. How many phyla are in the kingdom protista?

14

Video Notes: The Kingdom of Animals

Copy down the

outline, leaving

space for your

notes.

1. Introduction (2)

2. Kingdom of Protists (2)

3. Sponges (2)

4. Stinging Animals (3)

5. Spiny-skinned animals (2)

6. Worms (4)

7. Mollusks (2)

8. Arthropods (2)

9. Chordates (6)

15