Ch 9 Section 1: Classification: Sorting It All Out Objectives: Explain why and how organisms are classified. List the eight levels of classification. Explain scientific names. Describe how dichotomous keys help in identifying organisms. Sorting It All Out How is the school organized? Why is it important to have things organized? Why is it important to use a common language? Classification: the arrangement of organisms into orderly groups based on their similarities. 1
Why Classify? For thousands of years humans have classified organisms based on their usefulness. Example: Edible or poisonous plants Today classification is done to answer basic questions: How many species are there? What are their characteristics? What are the relationships between the species? A common system is needed so that scientists can answer those questions and share the information. 8 Levels of Classification Domain Largest group Kingdom one or more kingdoms make up a domain Phylum many phyla make up a kingdom Class many classes make up a phylum Order many orders make up a class Family many families make up an order Genus many genera make up a family Species only one type of organism The genus and species make up the scientific name of an organism. 2
Mnemonic device D K P C O F G S Example Kingdom Animalia Phylum Chordata Class Mammalia Order Carnivora Family Felidae Genus Felis Species domesticus Scientific Name: Felis domesticus 3
Example Kingdom Animalia Phylum Chordata Class Mammalia Order Primate Family Hominidae Genus Homo Species sapien Scientific Name: Homo sapien What is the basis for Classification? Carolus Linnaeus: Swedish physician and botanist in the 1700s. Created the science of identifying: taxonomy He attempted to classify all known organisms by their shared characteristics. Why is Linnaeus s method of classifying organisms incorrect? 4
Modern Classification Today s taxonomists look at evolutionary relatoinships. Species with a recent common ancestor can be classified together. Example: Mammalia: Platypus, brown bear, lion and house cat common ancient mammalian ancestor Carnivora: Brown bear, lion and house cat common ancient carnivore ancestor. Feline: Lion and house cat common ancient feline ancestor. 5
Branching Diagrams Branching diagrams show close evolutionary relationships between organisms. It shows common ancestors and common characteristics. It is based on the fossil record that can tell us when organisms lived what physical structures they share with other organisms. 6
Naming Names Most living things have a common name. Common names can be different in other languages. Scientific names are the same for every language, culture and country. Using a common system for naming can help clear up confusion among scientists when talking about an organism. Linnaeus created the 2 name system for naming organisms. Scientific names Scientific names are in the Latin or Greek language. In Linnaeus time Latin was spoken among all scientists, regardless of what country they were from. Latin names have complex meanings. Example: Tyrannosaurus rex tyrant lizard and king Example: Ursus americanus bear and American 7
Um Unique Scientific Names Megapnosaurus: big dead lizard extinct dinosaur Aegrotocatellus: sick puppy trilobite Colepiocephale: "knucklehead dinosaur Abra cadabra - clam Heerz lukenatcha snail Pieza pi fly Stupidogobius fish Supercrambus moth Dichotomous Keys A special guide to aid in identifying unknown organisms. A dichotomous key consists of several pairs of descriptive statements that have only two alternative responses. 8
From each pair of statements you must choose the answer that is correct for the unknown organism. This will lead you to another question that has two possible choices. By working through the statements in the key, a person can eventually identify the organism. Example: 1a. Internal skeleton go to 2 1b. No internal skeleton go to 3 2a. Pouch present kangaroo 2b. Pouch absent cow 3a. Six legs bee 3b. Not six legs spider 9