Domains and Kingdoms

and required information about Plants, Fungi, and Mutualisms

domain Bacteria

Kingdom names are not presently being used in this domain.

These are part of the large group of organisms commonly called "bacteria." They include the blue-green algae (= cyanobacteria), purple sulfur bacteria, etc., as well as most of the more familiar decomposing and disease-causing bacteria.

General Characteristics

domain Archaea

Kingdom names are not presently being used in this domain.

These are also part of the large group of organisms commonly called "bacteria."   Most of the thermophilic (hot-water-loving) and halophilic (brine-loving) organisms belong here, as well as sulfur-oxidizers that are mutualists with animals (such as Pogonophora) near submarine hot water vents, and the anaerobic decomposers that produce methane from organic wastes such as sewage and landfills.
Includes chemoautotrophic, photoautotrophic, and absorptive-heterotrophic (decomposer) metabolic types; does not include pathogens or the typical, aerobic decomposers of soils and underwater sediments.

General Characteristics

domain Eukarya

Unicellular protozoans (ciliates, amebas and flagellates), most kinds of algae, and all plants, fungi and animals.
Includes the ten kingdoms covered by the sixth edition of the Campbell and Reece textbook (Fig. 28.8), as well as many protozoans that are not placed in kingdoms in your textbook, often commonly called amebas and zooflagellates.  Three of the eukaryotic kingdoms - Parabasala, Diplomonadida, and Mycetozoa - in your textbook will not be covered in ZO 150.

General Characteristics:

Eukaryotic organisms not classified into candidate kingdoms.

Amebas and many photoautotrophic and heterotrophic flagellates are classified in kingdoms that we will not cover in ZO 150.  Recent estimates of the number of valid kingdoms range from 60 to 80.  Each is as genetically distinct from the others as any of the kingdoms we will be covering (e.g., plants and animals) are from each other.

For ZO 150, you must simply know that many amebas and zooflagellates belong to other kingdoms. This includes the sponge-like choanoflagellates, which are in an unnamed kingdom that is equally related to Fungi and Animalia by the most recent genetic studies.

kingdom Euglenozoa

Euglenas and other phyto- and zoo-flagellates, including the sleeping sickness pathogens called trypanosomes.

General Characteristics:

kingdom Alveolata

Ciliates, dinoflagellates and apicomplexans.

General Characteristics:

kingdom Stramenopila

Diatoms, golden algae, brown algae (including many seaweeds), and water molds

General Characteristics:

kingdom Rhodophyta

Red algae and red seaweeds.

General Characteristics:

kingdom Viridiplantae

Green algae, green seaweeds, stoneworts, and plants.

General Characteristics:

kingdom Fungi

Yeasts, mushrooms, shelf fungus, athlete's foot organism, mildews and molds (but not slime molds or water molds), plant rusts and smuts.

General Characteristics:

kingdom Animalia


General Characteristics:

Required Information About Viridiplantae and Fungi

Within the Viridiplantae, know relationships and distinctions among:

Know general characteristics of these fungal growth forms:

(which are neither taxonomic nor phylogenetic groups)

Examples of Inter-Kingdom Mutualisms

Each of these cases is a cooperative association of two distinct species from different kingdoms of life.  Know the kingdoms involved and how each member of the mutualism contributes to the growth, survival or reproduction of the other.

Fungi + green algae (Viridiplantae), or blue-green algae (Bacteria)
The fungus provides nutrient minerals, protection from drying, excess sunlight, and grazers for the alga, while the green or blue-green alga produces carbohydrates for the fungus by photosynthesis.

mycorrhizae (singular, mycorrhiza)
multicellular, rooted Viridiplantae + Fungi
The mycorrhizal fungus decomposes and transports mineral nutrients and water from soil into plant root cells much more efficiently than the plant root cell could do itself, while the fungus obtains carbohydrates for energy from the plant's root cells.

rhizobia (singular, rhizobium)
vascular Viridiplantae + nitrogen-fixing Bacteria
The rhizobial bacterium lives in plant root nodules and converts nitrogen gas (N2) from soil air into ammonia (NH3) as a nutrient for the plant, while the bacterium obtains carbohydrates for energy from the plant's root cells.

stony or reef-forming corals
Animalia (anthozoan cnidarians) + dinoflagellates (photosynthetic Alveolata) called "zooxanthellae."
The coral animal provides inorganic nutrients to the alga by capturing and digesting prey and releasing carbon dioxide from tissue respiration, while the alga produces carbohydrates for the animal by photosynthesis. 

termites and ruminant artiodactyls:
Animalia + flagellates (of several kingdoms), ciliates (Alveolata), and bacteria (Bacteria)
Protozoan and bacterial symbionts live in the animal's gut and digest cellulose and lignin for their host, while being maintained in a protected, moist environment and supplied constantly with fresh organic substrate (food) by the animal.  Many other kinds of herbivorous and detritivorous animals also have mutualistic bacteria to aid them in digesting cellulose and synthesizing vitamins and essential amino acids that they cannot synthesize for themselves.  Anaerobic archaeans also live in these gut communities and produce methane, but this chemical does not benefit the other members.

vent worms
Animalia (Pogonophora, and also a few bivalves and polychaetes) + Archaea (sulfide-oxidizers)
Prokaryotic symbionts live in a special organ of pogonophoran vent worms called the trophosome, which completely replaces the digestive tract of these gutless wonders.  The worm collects the dissolved sulfides (reduced, black sulfur compounds) that issue from submarine vents by using its tentacles with large surface areas and circulating blood containing hemoglobin.  The hemoglobin binds (just as it would to oxygen or carbon monoxide) and partially detoxifies the sulfides, then transports them to the trophosome.  The worm provides a steady supply of inorganic chemical substrate to the chemoautotrophic archaeans, which oxidize it to sulfate and use the released energy to synthesize biochemicals.  Pogonophorans use biochemical secretions and digested cells of archaeans as energy, and may also obtain energy by absorbing soluble biochemicals directly from the mud around them (absorptive heterotrophy).

pollination mutualisms
flowering Viridiplantae and insects, birds and bats (Animalia)
Many flowering plants provide nectar and excess pollen to animals as food, in exchange for the animals' transfer of the otherwise immobile pollen to the stamens of other plants or blossoms for sexual reproduction.  The animals tend to specialize in one particular species of flower, which greatly increases the likelihood that the pollen they carry will reach another plant or flower of the same species, where it can fertilize the ovule.  Some pollination mutualisms are obligatory, while others are more flexible.

seed dispersal mutualisms
seed-bearing Viridiplantae and insects, birds or mammals (Animalia)
Gymnosperms and angiosperms (collectively called spermatophytes) provide excess seeds or nutritious fruit as food for the animals, while the animals may bury some seeds they never recover, or pass undigested seeds through their guts and defecate them in new locations where the plant is likely to be able to germinate and survive, along with a little fertilizer.

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Maintained by Sam Mozley (click to send me E-mail)

Last modified on September 7, 2004