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Classifications of Organisms

Living oranisms are grouped into five kingdoms: Monera, Protista, Fungi, Plantae and Animalia. Each kingdom is further classified into divisions (or phyla for Animalia), classes, orders, families, genera and species. This classification are very important to identify and name individual species and to show the relationships between different species. Organisms are named using the binomial (two-name) system invented by Swedish naturalist Carolus Linnaeus (1708–78): genus as first part and species as the second part, such as Tillandsia usneoides. Sometimes there is also a third part to indicate subspecies or varieties of a particular species.


Prokaryotic (no membrane-bound subcompartments); single-celled.
Examples: bacteria, cyanobacteria (blue-green algae)

Protista (Protists)

Eukaryotic (have membrane-bound subcompartments or organelles); single-celled.
Heterotrophic: eat other organisms for energy.
(Divisions not listed)
animal-like (Protozoans):      Examples: amoebae, ciliates, flagellates
fungus-like:     Examples: slime and water molds
Autotrophic: make their own food by photosynthesis.

Chlorophylls and other pigments used in photosynthesis.
plant-like (algae)

Division Chlorophyta
(green algae)
contains chlorophyll A & B and carotenoids
Example: green seaweeds
Division Rhodophyta
(red algae)
contains chlorophyll A and phycobilins (red)
Example: Coralline algae
Division Phaeophyta
(brown algae)
contains chlorophylls A & C and fucoxanthin (greenish brown)
Example: giant kelp


Eukaryotic; mostly multicelluar.
Examples: fungi, molds, mushrooms, yeasts, mildews

Plantae (plants)

Eukaryotic; multicellular; cells have cell walls. Autotrophic: make their own food by photosynthesis.
Primary photosynthetic pigment: chlorophyll A; accessory pigments: chlorophyll B and carotenoids.

no true roots, stems or leaves
Division Hepatophyta (liverworts) no stomata or specialized nutrient-conducting cells
Division Anthocerophyta (hornworts) have stomata, no specialized nutrient-conducting cells
Division Bryophyta (mosses):

have specialized water and food conducting cells.
Class Bryidae
Class Sphagnidae: peat mosses.
One genus: Sphagnum, 350 species.
Class Andreaeidae: granite mosses.
Vascular plants

vascular system for nutrient conduction and supporting life on land

motile sperm;
fertilization requires water.
Division Psilotophyta Two genera, 3 species
Division Lycophyta 1000 species
Division Sphenophyta One genus: Equisetum; 24 species
Example: horsetails
Division Pterophyta The largest division:
about 230 genera, 12,000 species
Example: ferns
Seed plants
water no longer required for fertilization; pollination by wind or animal vectors.
(naked seeds)
Division Cycadophyta (cycads)
11 genera, about 140 species
Example: Zamia neurophyllidia
Division Ginkgophyta Only one species:
Ginkgo biloba (maidenhair tree);
Division Gnetophyta (genetophytes) Only one class (Gnetopsida) with 3 genera: Gnetum, Ephedra (Mormon tea) and Welwitschia
Division Coniferophyta (conifers) About 50 genera with 500 species;
primarily in cooler temperate zone.
Examples: pines, cypresses, redwoods, larches, cedars and yews etc.
(seeds in fruit)
Division Anthophyta (flowering plants) Class Liliopsida (monocots)
Class Magnoliopsida (dicots)

Animalia (animals)

Eukaryotic; multicellular; cells do not have cell walls. Heterotrophic: eat other organisms for energy.
Examples: sponges, worms, insects, fishes, amphibians, reptiles, birds, mammals

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