1. Animal Classification From Buckle Down Mississippi

2. Taxonomy Scientists believe that all life on the Earth arose from an ancient single- celled life-form. For this reason, all of the organisms that have ever lived on the Earth are related to each other—some distantly, and some not. Biologists figure out how closely different life-forms are related to each other by comparing their characteristics and putting them into groups.

3. Taxonomy is the science of naming and classifying organisms based on their similarities and differences. In the 1700s, the Swedish scientist Karolus Linnaeus developed a classification system for living things. His system involved grouping organisms into seven levels— kingdom, phylum, class, order, family, genus, and species. Taxonomy

4. In this system, the level of kingdom is the most general and contains the most types of organisms. The level of species is the most specific and contains only one type of organism. If you have trouble remembering the order of the taxonomic groups, just remember the phrase "Kings Play Chess On Fat Green Stools” The first letter of each word will help you recall the name of each level, in order from most general to most specific Taxonomy

5. An example will make clear how the Linnean system works. The following table shows how the Linnean system classifies a polar bear. The top level (kingdom) is the most general, containing all animals including the polar bear. The next level (phylum) is a little more specific, including only those animals that are vertebrates (have backbones). Taxonomy

6. Each level down gets even more specific, excluding more and more types of animals. The last level (species) contains only one type of animal— Ursus maritimus, the polar bear. Taxonomy

8. Linnaeus used two Latin names to describe an organism's genus and species. This method of naming organisms is called binomial nomenclature, a term that means "two-word naming system." Taxonomy

9. Organisms that are similar may have the same genus name but different species names. A tame dog is Canis (dog) domesticus (domestic), whereas the coyote is Canis (dog) latrans (barking). Notice that the genus name is capitalized, the species name is not capitalized, and both names are in italics. When writing an organism's genus and species name by hand, don't try to italicize them—-just underline them. Taxonomy

10. Back in the 18th century, Linnaeus only defined two kingdoms: Plantae and Animalia—plants and animals. Since Linneaus's time, scientists have added other kingdoms to the original two. The Kingdoms of Life

11. There are now five widely recognized Kingdoms –Monera –Protista –Fungi –Plantae –Animalia The Kingdoms of Life

12. Monera: Includes bacteria and blue-green algae. Monerans have no nuclei These are the most abundant life-forms on Earth. They also may have been the first: Scientists believe that photosynthetic monerans helped to oxygenate the Earth's atmosphere billions of years ago. The Kingdoms of Life

13. Protista: Includes amoebas, euglenas, and algae. Protists can be single celled and microscopic, but unlike monerans, they have nuclei. They can also be multicellular, but unlike plants or animals, they lack any specialized tissues and organs. They are commonly called protozoa. The Kingdoms of Life

14. Fungi: Includes mushrooms, yeasts, and molds. Yeasts are single celled, but most other fungi are multicellular. Fungi decompose other organisms, an important role in maintaining a healthy ecosystem. The Kingdoms of Life

15. *Plantae: Includes mosses, ferns, and trees. *Plants are multicellular and make their own food by absorbing sunlight. *They generally cannot move about freely. The Kingdoms of Life

16. Animalia: Includes microscopic animals, shellfish, and humans. Like plants, animals are multicellular, but they eat other life-forms for their nutrition. Most animals can move about freely. The Kingdoms of Life

17. Today, there isn't solid agreement about how many kingdoms there actually are. For example, many scientists argue that the kingdom Monera should be broken into two kingdoms: Archaebacteria ("ancient bacteria") and Eubacteria ("true bacteria"). The Kingdoms of Life

18. Archaebacteria thrive in extreme conditions—near volcanic vents under the sea or in hot springs too salty for other life- forms to survive. Many scientists believe that members of the kingdom Archaebacteria resemble the first organisms to evolve on the Earth. Members of the kingdom Eubacteria, in contrast, live everywhere on the planet—in water, in the air, in your body, and even on the page you are reading right now. The Kingdoms of Life

19. Kingdom Phylum Scientists use similarities and differences among body plans and internal structures to organize the vast diversity of life into groups called phyla (singular phylum).

20. All members of the phylum Arthropoda, for example, have a hard outer shell and jointed legs. Insects, spiders, and crabs are all types of arthropods. Kingdom Phylum

21. All members of the phylum Chordata start out their lives with a notochord—a long, flexible rod that runs along a central nerve cord. Kingdom Phylum

22. In vertebrates, the notochord develops into a spinal column with vertebrae. This flexible, tough spinal column protects the delicate nerve cord inside. Fish, amphibians, reptiles, birds, and mammals are all classes of vertebrates. Kingdom Phylum