Levels of Classification

Classifying Life • Classifications – grouping of organisms using similar characteristics

• Taxonomy – study of how organisms are classified

• Carl Linnaeus – created the system of naming organisms called binominal nomenclature

• Binominal nomenclature – two part naming system for organisms also called scientific name – Genus and species

• Genus – the second most specific level of classification

• Species – most specific level - group of similar organisms that can mate with each other and their offspring can also mate

Classification of Living Things:Eight Levels of Classification

1 - Domain:

• Most general level of classification

• There are three domains – Bacteria, Eukaryotes, Archaea

• Bacteria are prokaryotes, which are single celled organisms that lack a nucleus.

• Eukaryotes are single-celled or multi-celled organism with a nucleus and other organelles in their cells.

• Archaea are prokaryotes often found in very harsh environments such as hot springs and very salty water.

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• The four kingdoms of Eukarya are Protista , Plantae, Fungi, and Animalia

• Archaea and bacteria have different kingdoms

There are four Kingdoms under Domain Eukarya

Protista• Extremely diverse• Autotrophs and heterotrophs in the

Protista kingdom• Most unicellular • some multicellular

Fungi• Heterotrophs• Athletes foot – eat skin cells• Most are multicellular • Some unicellular

• Plantae• Autotrophs• Photosynthesis• Cell walls • Multicellular

• Animalia • Heterotrophs• Most multicellular

• Autotroph = make food• Heterotroph = eat food

Phylum: • Placed into phylum by generalization of

body plan

• certain morphological or developmental similarities

• Examples

• Cnidaria – jellyfish

• Mollusca – clams, snails

• Chordata – lions, turtle , eagle

• Coniferophyta – pines, firs

Class• further divides organisms of a

phylum

• organisms of a class have even more in common than those in an entire phylum

• Examples include Mammalia, Reptilia, Aves

Order and Family • Order:

• subdivision of a Class• Some orders are group by what animal eats• Some orders are grouped by how a plant flowers

• Example: carnivore , Asterales

• Family• Orders are divided into families. • share so much in common, organisms of a family are said to be

related to each other. • Humans are in the Hominidae Family.

Genus and Species

• Genus• describes the generic name for an organism• very specific so there are fewer organisms within each one• There are a lot of different genera among both animals and

plants

• Species• Is as specific as you can get• It is the lowest and most strict level of classification• The main criterion for an organism to be placed in a particular

species is the ability to breed with other organisms of that same species

Writing Scientific Name

• The genus is used to determine the first part of its two-part name.

• The species of an organism determines the second part of its two-part name.

• How to write genus and specis

• The genus has to be capitalized

• The species has to be lower cased

• If typed must all be italicized (slant)

• If written must be underlined

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