Biological Classification

Why classify?

• Humans have developed classification systems in order to make sense of the abundant biological diversity that exists in nature.

Taxonomy

• …the identification, naming, and classification of species

• Taxonomists spend their time searching for previously unknown organisms, determining their relationships to known organisms, and giving them names.

The Linnaean System of Classification

• The system is hierarchical.– Larger groups are more general and

smaller groups are more specific.– For example, the phylum Chordata

includes both lions and lionfish, but the genus Panthera includes only lions.

Chordata

Panthera

The Linnaean System of Classification

– Homologous structures are the clues used to assess how closely organisms are related.

• The system is phylogenetic.– It is meant to reflect the

evolutionary interrelatedness among groups.

– For example, the grey wolf and the dog both are placed in the genus Canis because of their close evolutionary relationship.

grey wolf dog

• Kingdom

• Phylum

• Class

• Order

• Family

• Genus

• Species

Seven Levels of Taxonomic Classification

Kingdom, Phylum…what?

• An easy way to remember the classification levels:

“Kansas Predators Catch Old Furry Grey Squirrels”

• Try to make up your own!

Seven Levels of Taxonomic Classification

for the…

• Kingdom

• Phylum

• Class

• Order

• Family

• Genus

• Species

Grizzly Bear

Kingdom

• The most general of the seven levels.

• Traditionally, biologists have recognized five different kingdoms: Monerans, Protists, Fungi, Plants, Animals

Phylum (plural: phyla)

• Each kingdom is subdivided into smaller, more specific groups called phyla.

Class

• Each phylum is subdivided into smaller groups called classes.

Order

• Each class is subdivided into smaller groups called orders.

Family

• Each order is subdivided into smaller groups called families.

Genus (plural: genera)

• Each family is subdivided into smaller groups called genera.

Species

• Each genus is subdivided into smaller groups called species.

• The species is the most specific level of classification.

Scientific Names

• The scientific name (binomial) of an organism contains two parts—the name of the genus and the name of the species.

Writing Scientific Names

• The rules for writing scientific names:

-CAPITALIZE the first letter of the genus name.

-Do not capitalize the species name.

-Both names must be underlined or italicized.

• Example: human = Homo sapiens

• Kingdom-Animalia

• Phylum-Chordata

• Class-Mammalia

• Order-Carnivora

• Family-Felidae

• Genus-Panthera

• Species-leo

Seven Levels of Taxonomic Classification

for the…Lion

• Kingdom-Animalia

• Phylum-Chordata

• Class-Mammalia

• Order-Primates

• Family-Hominidae

• Genus-Homo

• Species-sapiens

Seven Levels of Taxonomic Classification

for the…Human

• Kingdom-Protista

• Phylum-Sarcodina

• Class-Rhizopoda

• Order-Amoebida

• Family-Amoebidae

• Genus-Amoeba

• Species-proteus

Seven Levels of Taxonomic Classification

for the…Amoeba

• Kingdom-Animalia

• Phylum-Chordata

• Class-Mammalia

• Order-Carnivora

• Family-Canidae

• Genus-Canis

• Species-familiaris

Seven Levels of Taxonomic Classification

for the…Dog

Seven Levels of Taxonomic Classification

for the…

• Kingdom: Animalia

• Phylum: Chordata

• Class: Mammalia

• Order: Xenarthra

• Family: Myrmecophagidae

• Genus Tamandua

• Species: tetradactyla

Collared Anteater