18-3 Kingdoms and Domains

As biologists learned more about the natural world, it became apparent that Linnaeus’s 2-kingdom system was too simple.

Today, we use 6 Kingdoms for classification:

1. Plants (Plantae)2. Animals (Animalia)3. Protists (Protista)4. Fungi 5. Eubacteria6. Archaebacteria

Kingdom Plantae

• Land plants include mosses, liverworts, hornworts, and vascular plants like trees and ferns

• Obtain energy through photosynthesis

Kingdom Animalia

• Multicellular, eukaryotic , heterotrophic organisms

• Water bears (Tardigrades) are eight-legged microscopic animals that are extremophiles– They can survive temp. of -

273° C to over 151° C, 1,000 times more radiation than other animals, and live a decade without water. They have also lived over 10 days in the vacuum of space.

Kingdom Protista

• Protists are mostly unicellular, eukaryotic organisms

• They include protozoa, ciliates, some molds and algaes.

• Red algae is a multicellular example of a protist

Kingdom Fungi• Fungi include mushrooms,

molds, and yeasts. • Fungi are more related to

animals than plants!• Eukaryotic decomposers

– NA Destroying angel (Amanita bisporgia) death by liver hemorrhage within 2 days in most cases.

– Most toxic mushroom in North America

Kingdom Eubacteria

• Single-celled, prokaryotic microorganisms

• True bacteria• Biomass greater than all

plants and animals on Earth

• 10x as many bacterial cells in human flora as there are cells in human body

Kingdom Archaebacteria

• Single-celled organisms with no nucleus and no membrane-bound organelles

• Extremophiles• Halophiles – extreme

salt• Thermophiles –

extreme heat

To organize all of these kingdoms, biologists use 3 domains.

1.Eukarya- protists, fungi, plants, and animals; uni- and multicellular, eukaryotes

2.Bacteria- eubacteria; unicellular prokaryotes, “true bacteria”

3.Archaea- archaebacteria; unicellular prokaryotes, no O2, extreme environments.

Exit Slip

1. What are the three Domains of life?

2. Which Domains include only prokaryotic organisms? Which are only eukaryotic?