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. Eubacteria 6. 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. Eukarya- protists, fungi, plants, and animals; uni- and multicellular, eukaryotes Bacteria- eubacteria; unicellular prokaryotes, “true bacteria” Archaea- archaebacteria; unicellular prokaryotes, no O2, extreme environments.

Exit Slip What are the three Domains of life? 2. Which Domains include only prokaryotic organisms? Which are only eukaryotic?