Classification of Living Things

Unit II

pp 98

Why There is a Need for Classifying

–There are over 2 million different types of organisms known.

–biologists can organize living things into groups.

Taxonomy

•naming and placing of all organisms into groups.

• science of classifying organisms

Early Classification Schemes

•placed all organisms into one of two groups.

Early Classification

Plants Animals

Living Things

Classification by Aristotle and Theophrastus

• Aristotle classified animals according to where in the environment they lived.

• Theophratus classified plants according to their stem structure

Aristotle's Classification

Air Dwellers Land Dwellers Water Dwellers

Animals

Theophrastus's Classification

Herbs

(soft stem)

Shrubs

(Several woddy stems)

Trees

(single woody stem)

Plants

•The early schemes were based mainly on structural similarities.

•In 1866 Ernst Haeckel added another Kingdom called Protista

•Fungi such as mushrooms and mold were first placed in the plant kingdom, but warranted their own kingdom as they do not carry out photosynthesis, as plants do.

•The Kingdom Protista was further subdivided into:

–Protista

–Monera

based on their cellular structure

•In the early 1970’s

–Monera

•Kingdom Bacteria

•Kingdom Archaea

Biological Domains and Kingdoms

•Today

–3 Domains

–6 Kingdoms

Domains

Kingdom

Bacteria

Domain

Bacteria

Kingdom

ProtistaKingdom

FungiKingdom

PlantaeKingdom

Animalia

Domain

Eukarya

Kingdom

Archaea

Domain

Archaea

Living Things

Kingdom MONERA(Bacteria)

•Also called Kingdom Bacteria

•Unicellular

•Prokaryotic

•may be photosynthetic, chemosynthetic, or feed by absorption.

Bacteria

Kingdom PROTISTA

• Also called Archaebacteria

• These bacteria like organisms posses a differing cell wall composition that allows them to survive extreme conditions such as salt lakes, or hot acidic springs

Archaea

Domain Eukarya

•This domain includes all living organisms that are composed of one or more Eukaryotic cells

•Protista, Fungi, Plantae, and Animalia

Kingdom Protista

•Most are unicellular

•Eukaryotic

•may be photosynthetic, may feed by absorption, or may ingest food.

Protists

Kingdom Fungi

•Most multicellular although some are unicellular.

•Eukaryotic cell structure

•Absorptive Heterotrophs

•Non Motile

Fungi

Kingdom Plantae

•Multicellular

•Eukaryotic

•Photosynthetic

•Non Motile

Plants

Kingdom Animalia

•Multicellular

•Eukaryotic

•Ingestive Heterotrophs

•Motile

•Nervous system present

Animals

Classification Categories

•Within any Kingdom there are many levels of classification.

Carl Linnaeus

• Linnaeus attempted to classify all known species of his time (1753).

Linnean hierarchical classification was based on the premise that the species was the smallest unit, and that each species (or taxon) nested within a higher category

• Domain

• Kingdom

• Phylum

• Class

• Order

• Family

• Genus

• Species

• Within any kingdom there are many phylum

• Within any phylum there are several classes

• Within any Class there are several Orders

• Within any order there are several Families

• Within any Family there are several Genus

• Within a Genus there may be many species

•Every Organism on earth is placed into each of the classification categories

Humans

• Kingdom Animalia

• Phylum Chordata

• Class Mammalia

• Order Primates

• Family Hominidae

• Genus Homo

• Species Sapien

Domestic Dog

• Kingdom Animalia

• Phylum Chordata

• Class Mammalia

• Order Carnivora

• Family Canidae

• Genus Canis

• Species familaris

Wolf

• K. Animalia

• P. Chordata

• SubP. Vertebrata**

• C. Mammalia

• O. Carnivora

• F. Canidae

• G. Canis

• S. lupus (Latin for wolf)

Naming Organisms

•taxonomists also name each type of living organism.

•Naming is also called Nomenclature

Binomial Nomenclature

• devised by Linnaeus

• two names: genus and species

• Latin

• Genus has first letter capitalized, species all lower case

• underlined or italicized

Examples

•Homo sapiens - Humans

•Canis familaris - dog

The use of Latin in naming

•Universally used

•the language of scholars

Common Names

•organisms may also be given common names.

Common names can cause confusion

• StarFish - not a fish

• green pepper is also referred to as a bell pepper, sweet pepper

•Common names also vary from language to language

•Dog - perro - inu

• Cougar, Mountain Lion,

Puma

Today’s Classification Schemes

•Taxonomy centers around evolutionary relationships

Today’s Classification Schemes

•Taxonomists use a variety of information to classify or group organisms.

•Fossil Record

•Structural

•Biochemical

•Cytological Information

•Embryological Information

•Behavioral

TRANSITIONAL FOSSILS LINKING PAST AND PRESENT Basilosaurus (ancient whale)

Homologous Structures

VESTIGIAL STRUCTURES