Biologists use 7 Levels of Classification Linnaeus named about 4000 species Carolus Linnaeus developed systems for naming & organizing species into groups. Today scientists have named over 1 million species with help of modern technology NAMING SPECIES USING SCIENTIFIC NAMES Organisms can be classified into 7 levels Dichotomous keys and field guides help people identify organisms

NAMING SPECIES A genus is a group of species that have similar characteristics. Ursus groups all are bears; include Ursus arctos(grizzly) & Ursus maritimus(polar) . Linnaeus developed a binomial nomenclature system for modern taxonomy. Binomial = 2 names and nomenclature = list of names. It is a system of naming something using 2 names or words (most are Latin terms). If genus name isn’t included, species may by mystery (all 3 below are species “gracilis, meaning slender/graceful in Latin. Genus always comes first, first letter is capitalized, and entire name is in italics. Species name is second & is italicized too, all in lower case.

7 Levels of Classification The largest level is the kingdom, the group with the most species. Below is an example for a housecat. Kingdom (Animalia- the animals) Phylum (Chordata- animals with backbones) Class (Mammalia-mammals that nurse their young) Order(Carnivora-carnivores that kill or eat other animals) Family(Felidae-the cat family) Genus(Felis-housecats, cougars & many others) Species(catus-all housecats, no matter what breed) The more names an organism shares with another organism, the more closely related the 2 organisms are.

7 Levels of Classification Scientists can compare very broad categories of organisms, like kingdom & phyla, or very specific categories, like species. Can remember classification levels by: Kings Play Chess On Fat Green Stools. A human is classified like this: Kingdom Animalia, phylum Chordata, class Mammalia, order Primates, family Hominadae, genus Homo, and species sapiens.

Dichotomous Key/Field Guide Taxonomists have come up with a tool to identify organisms like beetles (over 300,000 known species). A dichotomous key= asks a series of questions that can be answered in only 2 ways. Each answer leads to another question with only 2 choices. Eventually, you will identify the organism. The questions in a dichotomous key gradually narrow down the list of possible organisms. Field Guides are another tool for identifying organisms. It includes paintings or pictures of familiar species. Flower guides may start with the flower’s color, while bird guides are arranged by orders & families. Field guides also include maps where organisms live.