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Linnaeus and Taxonomy
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More than 1.5 million species of animals are named
 Estimated that these account for
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Less than 20% of all animals currently alive
Less than 1% of extinct animals
Taxonomy (aka - Systematics)
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Formal system for naming and classifying species
Science of classifying organisms based on similarity, biogeography, molecular components, development, etc.
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Linnaeus and Taxonomy
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Greek philosopher Aristotle first classified organisms (350 BC)
Carolus Linnaeus designed the current system of classification (1750)
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Swedish botanist with experience classifying flowers
Used morphology (study of form and structure) to develop a classification system of animals and plants
Divided animal kingdom into species and gave each a distinctive name
 Grouped species into genera, genera into orders, and orders into classes
His classification scheme has been drastically altered, but the basic principle is still followed
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Linnaeus and Taxonomy
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Hierarchy of taxonomic ranks now includes 7 major groups
 Kingdom, phylum, class, order, family, genus, and species
Now, the new level of Domain is also used.
All animals are placed in Kingdom Animalia, or
Domain Eukarya
Taxa (Taxon) Groups of animals that share a particular set of characteristics.
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Example: True Flies “Diptera” - single pair of wings
 Each rank can be subdivided into additional levels of taxa
 Superclass, suborder, etc.
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Linnaeus
1735
2 ki ngdoms
Haeckel
1866 [5]
3 ki ngdoms
Chatton
1937 [6]
2 em pires
Copela nd
1956 [7]
4 ki ngdoms
Whittaker
1969 [2]
5 ki ngdoms
Woese et al.
1977 [3]
6 ki ngdoms
Woese e t al.
1990 [8]
3 domai ns
(not treated)
Vegetab ilia
Animalia
Protista
Plantae
Animalia
Proka ryota Mone ra
Protista
Euka ryota
Plantae
Animalia
Mone ra
Protista
Fung i
Plantae
Animalia
Eubacte ria Bacte ria
Archaebacte ria Archaea
Protista
Fung i
Plantae
Animalia
Euka rya

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Taxonomy
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Nomenclature: assignment of a distinctive name to each species
A scientific name of an animal consists of two words (binomial nomenclature)
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First word is the genus and is capitalized
Second is the species written in lower case
Scientific name should be printed in italics or underlined if handwritten
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Homo sapiens
Homo sapiens
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Taxonomy
 Some animals are subspecies, usually caused by Geographic locations. They are referred to as trinomials (3 names)
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All three terms are in italics
Subspecies is also in lower case
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Ensantina eschscholtzii (salamander) has many subspecies.
 E.e. plantens, E.e. picta, E.e.croceater

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Taxonomic Characters and Phylogenetic Reconstruction
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Cladogram
 Diagram illustrating hierarchy of clades (groups of animals with common ancestry)
 Outgroups used
Phylogenetic tree
(compared to cladogram)
 Additional information concerning:
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 ancestors, duration of lineages,
 amount of evolutionary change
(some mathematical calculation and numerical values usually invovled)
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Amphioxus is the “outgroup” because it doesn’t share any of the defining characteristic with the other taxa. What characteristic separates Bass from
Horses?

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Taxonomic Characters and Phylogenetic Reconstruction
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(What do we use to identify animals in a
Phylogenetic Tree??)
 Comparative Morphology
 Examines shapes, sizes and development of organisms
 Skull bones, limb bones, scales, hair and feathers
 Living specimens and fossils are used
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Taxonomic Characters and Phylogenetic Reconstruction
 Comparative Biochemistry
 Analyzes sequences of amino acids in proteins and nucleotides sequences in nucleic acids
 Comparative biochemistry can be applied to fossils
 Comparative Cytology
 Examines variation in number, shape and size of chromosomes
 Used almost exclusively on living specimens
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Phylogenetic Tree based
On Cytology:
Comparing base substitutions on
Cyctochrome C
(a respiratory protein).
#’ s represent number of
Mutations that occurred at the ancestral division.
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Symmetry
 Asymmetrical (no central body point/axis) ex. sponge
 Embryonic Tissue
Layers:
 Diploblastic - 2 tissues
(ectoderm and endoderm)
 Bilateral (if divided right/left sides are mirror image) ex. vertebrates
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 Triploblastic - 3 tissue layers (also mesoderm)
Zygote Cleavage
 Radial (any plane cut through organism makes mirror image) ex. Sea anemone
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Protostome - blastopore becomes mouth
Deuterostome blastopore becomes anus

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Major Subdivisions of the Animal Kingdom
 Traditional groupings based on embryological and anatomical characters
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Major Subdivisions of the Animal Kingdom
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 Grade I (Radiata): phyla Cnidaria
 Grade II (Bilateria): all other phyla
 Division A (Protostomia):
Mouth is first opening
Subdivision of Protostomes by coelom formation:
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Acoelomates: phyla Platyhelminthes,
Pseudocoelomates: phyla Nematoda,
Eucoelomates: phyla Mollusca, Annelida,
Arthropoda
 Division B (Deuterostomia):
Anus is first opening
 phyla Echinodermata, Chordata
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