CLASSIFICATION

Why Do We Classify? We classify in order to organize. We classify to recognize relationships among organisms. We classify to study the evolutionary history of organisms (phylogeny).

History of Classification Aristotle was a Greek philosopher and scholar. Divided organisms into 2 groups - plants and animals. –Divided animals into groups based on number of legs. –Divided animals into 3 groups according to how they moved - walking, flying, or swimming (land, air, or water)

History of Classification Carolus Linnaeus was a Swedish scientist, who like Aristotle, based his groupings on similarities in appearance. Divided living things into one of two "kingdoms" – Plant or Animal. Divided each of the kingdoms into smaller groups called genera or “genus”. Divided each genus into smaller groups called "species“.

The Evolution of Our Classification System The Linnaean System is used by scientists all over the world, but has been expanded to include new and different living things as they are discovered. It will continue to grow as human knowledge grows.

Classification Terminology CLASSIFICATION – TAXONOMY – ORGANISM – BINOMIAL NOMENCLATURE – EVOLUTION – Grouping things based on their similarities. The science of classifying organisms. Any living thing. A two-part scientific name (Genus species). Species change gradually over time.

Our Current Classification System The classification system in use today places each living thing into a series of specific groups based on similarities and differences in body structure, color, behavior, etc.

Our Current Classification System The largest group into which any living thing can be classified is its kingdom. This is followed by its phylum, then its class, order, family, genus, and finally its species.

The Kingdoms Most biologists use a classification system based on five kingdoms.

The Kingdom Debate The number of kingdoms is often under debate, depending on how scientists interpret current research. For example, some scientists separate the Moneran into two kingdoms.

Our Hierarchical System Taxonomists divide organisms into a series of groups (divisions) that get more and more specific. The most general division of life is a kingdom. The most specific division of life is a species.

Our Hierarchical System Within each kingdom, there are groups, increasing in commonality and evolutionary relationships, but decreasing in size (fewer numbers). For example, two organisms in the same order have more in common than two organisms in the same class.

Moneran Kingdom Bacteria are among the oldest living organisms on Earth, and are very small. Bacteria can only be seen through a microscope. Bacteria are unicellular prokaryotes. Bacteria is commonly found in the ground, water and in other living organisms. Most bacteria are heterotrophs but some are autotrophs.

Moneran Kingdom While some types of bacteria can cause diseases and become harmful to the environment, animals and humans, others offer benefits that we likely could not live without.

Harmful Bacteria Some types of bacteria can attack plants, causing diseases like leaf spot and fire blight.

Harmful Bacteria In human hosts, certain types of bacteria can cause diseases and illnesses. Humans can be treated with antibiotics, which kill bacteria or at least hamper their growth. Antiseptics, sterilization and disinfectants can help prevent contamination and risk of infection from bacteria.

Helpful Bacteria The term “friendly bacteria” is used to describe the types of bacteria that offer some benefit. Not only does bacteria help produce the food we eat and keeps the soil fertile, it also helps us digest our food. Bacteria in our digestive system help to break down protein and inhibit the growth of potentially harmful bacteria.

Archaebacteria vs. Eubacteria Archaebacteria –“ancient bacteria” –They survive in very harsh environments such as sea vents, hot springs or boiling mud around volcanoes. –“extremophiles” –All forms of archaebacteria are non- pathogenic. Eubacteria –“true bacteria” –Most bacteria are in this kingdom. –They are the kinds found everywhere and the ones people are most familiar with.

Archaebacteria vs. Eubacteria

Protozoan Kingdom This is sometimes called the “odds and ends” kingdom. unicellular Can be heterotrophic or autotrophic. Most live in water ALL are eukaryotic (have a nucleus).

Classification of Protists How they obtain nutrition How they move Animal-like Protists - protozoa - heterotrophs Plantlike Protists - algae autotrophs Fungus-like Protists – heterotrophs & decomposers

Fungi Kingdom Mushrooms Molds Yeasts Mildews

Fungi Kingdom Most fungi are multicellular (yeast is unicellular). All fungi are eukaryotic heterotrophs. Fungi can be found almost everywhere on land, but only a few live in fresh water.

The Importance of Fungi Decomposers - breaking down dead organic material cycling of nutrients through the environment. Provide numerous drugs (such as penicillin) Food source - mushrooms, truffles and morels Fermentation - cause the bubbles in bread, champagne, and beer Yeasts, are important "model organisms" for studying problems in genetics and biology.

Bad Fungi? Humans –ringworm –athlete's foot Plants –rusts –Smuts –leaf, root, and stem rots –damage to crops

Plant Kingdom

Plants are multicellular eukaryotes. Plants are autotrophs and make their own food through the process of photosynthesis. Plants feed almost all of the heterotrophs on Earth.

Animal Kingdom

All animals are multicellular eukaryotes. All animals are heterotrophs. Animals have adaptations that allow them to find food and digest it. Members of the animal kingdom are found in diverse environments on earth.

Invertebrates

Vertebrates

The Evolution of the Animal Kingdom

The Organization of Life...

... ever changing!