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Taxonomy
The Naming and Classification of
Life
I. Taxonomy: the branch of biology that deals with the naming and
classification (grouping) of living and extinct organisms.
• Taxon = group
a) Methods of Classification
•
Organisms (living things) are classified based upon physical
(anatomical) and genetic (DNA) similarities.
•
Organisms that are placed into groups can be said to closely
related in terms of evolution.
• Evolution: the theory that organisms today have come from more
primitive organisms from the past. The theory states that organisms have
changed over long periods of time.
b) Reason for Classification
•
The classification of life is necessary to enable biologists to more easily
study living things.
c) Father of Modern Classification System
Carolus Linnaeus
d) Organization of Taxonomy
• Organisms are grouped into seven major taxons:
KINGDOM
(large, broad, most organisms, least similarities)
PHYLUM
CLASS
ORDER
FAMILY
GENUS
SPECIES
(small, specific, least organisms, most similarities)
e) Five Kingdom System:
1. Monera – unicellular; simple; microscopic; no membrane-bound
organelles; no nucleus; some are autotrophic while others are heterotrophic;
prokaryotes.
Bacteria
Ex: Eubacteria, archaebacteria
Archaebacteria
Eubacteria
“ancient bacteria”
“true bacteria”
• inhabit some of the
most extreme
environments on the
planet.
• differ from eubacteria
in the chemical
composition of cellular
structures.
Extremeophiles
Morphology
•thermophiles (heat)
•Halophiles (salt)
•acidophiles (acids)
•alkaphiles (bases)
•methanogen (methane)
• cocci (spheres)
• bacillus (rods)
• spirillum (spirals)
From: http://commons.wikimedia.org/wiki/File:Arrangement_of_cocci_bacteria.svg
2. Protist – unicellular; simple (but more complex than monera);
microscopic; have organelles; have a nucleus; some are autotrophic
while others are heterotrophic; eukaryotes.
Ex: Ameba, Paramecium, Algae
Ameba
Paramecium
Euglena
Algae
From: http://www.fcps.k12.va.us/StratfordLandingES/Ecology/Plants/Green%20Algae/07.jpg
3. Fungus: multicellular; complex, macroscopic; heterotrophic; consume
dead plant material (saprophytes).
Ex: mushrooms, yeast, mold
Yeast
Mushroom
Mold
4. Plants:
• multicellular; complex; autotrophic (photosynthesis); macroscopic.
Ex: grass, shrubs, bushes, trees, moss
• Bryophyta – lacks vascular tissue such as xylem and phloem.
Ex: moss, liverworts, and hornworts.
• Tracheophyta -are plants with roots, stems
and leaves. Some tracheophytes reproduce
with seeds and some reproduce with spores.
• Tracheophytes have vascular tissue:
xylem and phloem.
• Gymnosperms: a group of vascular plants whose seeds are not
enclosed by a ripened ovary (fruit). The seeds of many gymnosperms
(literally, "naked seed") are borne in cones and are not visible.
• Angiosperms:
• Angiosperms are flowering plants. Angiosperms are the biggest group
in the plant kingdom. They have true roots, stems, leaves and flowers.
They also have seeds. The seeds are formed when an egg or ovule is
fertilized by pollen in the ovary. The ovary is within a flower. The flower
contains the male and/or female parts of the plant. Fruits are frequently
produced from these ripened ovaries.
5. Kingdom Animalia:
• Characteristics: Eukaryotic, multicellular, heterotrophic, lack of cell
walls, interior digestion of food, possession of a digestive tract where
hydrolytic enzymes are secreted and digestion takes place, and special cell
junctions in their tissues.
• Kingdom Animalia is thought to have arose in the sea, from
colonial protists.
• The most well known phyla of kingdom Animalia are the Porifera,
Cnidaria, Mollusca, Platyhelminthes, Nematoda, Annelida, Arthropoda,
Echinodermata, and Chordata. There are more than 35 phyla in all, but
these nine generally comprise the bulk of the kingdom.
PORIFERA
1. PORIFERA
“PORE BEARING”
SIMPLEST
ANIMALS
- Filter feeders
- have choanocytes
EXAMPLES:
SPONGES
CNIDARIANS
2. CNIDARIA
(Coelenterates)
“STINGING
CELLS”
- nemotocysts
EXAMPLES:
CORAL,
JELLYFISH,
SEA ANEMONE,
HYDRA
MOLLUSCA
3. MOLLUSCA
“SHELL
MAKER”
EXAMPLES:
CLAMS,
OYSTERS,
SNAIL,
SCALLOP,
OCTOPUS,
SQUID
Platyhelminthes
4. PLATYHELMINTHES
“FLAT WORMS”
- acoelomates
EXAMPLES:
Planaria, Fluke,
Tapeworm
Nematoda
5. NEMATODA
“ROUND WORMS”
- pseudocoelomates
EXAMPLES:
HOOKWORMS,
HEARTWORMS
Annelida
6. ANNELIDA
“SEGMENTED WORMS”
- coelomates
EXAMPLES:
LEECHES,
EARTHWORMS
Arthropoda
7. ARTHROPODA
“JOINTED APPENDAGES”
SEGMENTED
ANIMALS
- exoskeleton of chitin
- open circulatory system
EXAMPLES:
Insects, Arachnids, Crustaceans,
Centipedes, Millipedes, Horseshoe
Crabs
Echinodermata
8. ECHINODERMATA
“SPINY SKIN”
- Water vascular system with tube feet.
EXAMPLES:
SEA URCHIN,
SEASTAR,
BRITTLE STAR
Chordata
9. CHORDATA
- Pharyngeal gill slits
- post anal tail
- Hollow, dorsal nerve cord
- notochord
- mouth and anus
- brain
EXAMPLES:
FISH, REPTILES, BIRDS,
AMPHIBIANS, MAMMALS
II. DETERMINING PHYLOGENETIC RELATIONSHIPS
(CLADISTICS AND CLADOGRAMS)
a) PHYLOGENY: The history of descent of organisms which is based upon
taxonomy and evolution.
b) The establishment of a hierarchy based upon comparative anatomy and
biochemistry is valuable in indicating the relatedness between organisms.
c) Cladograms are branching diagrams to show a hierarchical
distribution of shared characters.
• Phylogenies are determined by constructing
cladograms.
• Each branch (or bundle of branches) of a phylogeny is
called a clade (from "clados" meaning branch).
d) A divergence is a split on a cladogram. Convergence is the evolution of
similar features in two unrelated (or distantly related) clades.
e) The manner in which organisms are related is defined as their
phylogenetic relationships (or evolutionary relationships).
Cladogram showing the phylogenetic relationships of vertebrates
(From: American Museum of Natural History: Understanding Cladistics at
http://www.amnh.org/Exhibition/Fossil_Halls/cladistics.html).