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 blood and bloodless.

• 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. • Classified plants and

animals according to similarities in form.

• Divided living things into one of two "kingdoms" – Plant or Animal

• Divided each of the kingdoms into smaller groups called "genera" (plural of "genus").

• Divided each genera 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 or division, 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. • Because the bacteria structure is so minute, it

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 somebacteria like blue-green algae 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 tetanus, pneumonia, syphilis, tuberculosis and other 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 convert milk protein into lactic acid and inhibit the growth of potentially harmful bacteria.

Archaebacteria vs. Eubacteria

• Archaebacteria– “ancient bacteria”– Found in very harsh

conditions such as in the volcanic vents or at the bottom of the sea.

– They survive in the environments such as sea vents releasing sulfide-rich gases, hot springs or boiling mud around volcanoes.

– “extremophiles”– All forms of

archaebacteria are non-pathogenic.

• Eubacteria

– “true bacteria”

– Cyanobacteria – blue-green algae

– 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.

• A protist is any organism that is not a plant, animal or fungus.

• Mostly unicellular, some are multicellular (algae)

• Can be heterotrophic or autotrophic.

• Most live in water (though some live in moist soil or even the human body).

• 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• Fungi are some of the most

important organisms in terms of their ecological and economic roles.

• By breaking down dead organic material, they continue the cycle of nutrients through ecosystems.

• Most vascular plants could not grow without the fungi that inhabit their roots and supply essential nutrients.

• Other fungi provide numerous drugs (such as penicillin and other antibiotics), foods like mushrooms, truffles and morels, and the bubbles in bread, champagne, and beer.

• A number of fungi, in particular the yeasts, are important "model organisms" for studying problems in genetics and molecular biology.

Bad Fungi?

• Fungi also cause a number of plant and animal diseases.

• In humans, ringworm, athlete's foot, and several more serious diseases are caused by fungi.

• Plant diseases caused by fungi include rusts, smuts, and leaf, root, and stem rots, and may cause severe 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.

Plant Kingdom

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.

Animal Kingdom

Animal Kingdom

Invertebrates

Vertebrates

The Evolution of the Animal Kingdom

The Organization of Life . . .

. . . ever changing!