Classification of Living Things

Definitions1. Taxonomy – the science of classifying

organisms based on biological similarities

2. Carolus Linnaeus – the father of taxonomy

3. Binomial nomenclature – the way that organisms are named using two word Latin descriptions

4. Kingdom – the most general description of living things (6)

5. Phylum – the second level of classification

Definitions cont…6. Class – the third level of classification

7. Order – the fourth level of classification

8. Family – the fifth level of classification

9. Genus – a Latin name that describes a specific organism

10. Species – the most specific level of classification

Definitions cont…..11. Eubacteria – a unicellular kingdom of bacteria that

have a cell wall and a cell membrane made of carbohydrates

12. Archaebacteria – a unicellular kingdom of bacteria that are way different than the eubacterias

13. Plantae - multicellular kingdom of organisms that include flowering plants, mosses, and ferns

14. Animalia – a multicellular kingdom of organisms that includes an incredible diversity of animals

15. Fungi – a multicellular kingdom of organisms that can not move to get their food

Definitions cont….16. Protista – unicellular kingdom of organisms that

contain organelles and a nucleus

17. Dichotomous Key – a tool used by scientists to determine the scientific name of an organism

18. Scientific name - the name given to an organism using the genus and species name

19. Common name – a nickname given to an organism

20. classification – placing organisms into similar groups

The "Nuts and Bolts" of Taxonomy and Classification

Why Classify?There are more than 2.5 million different

living things on earth.Millions more have not yet been discovered.Life is diverse and needs to be organized.It is organized so that scientists all over the

world have a universal method of classifying.Organisms are placed into groups with

biological similarities.

History of Classification:

• Aristotle - 2000 years ago

• Plant or Animal

Stem differences Land dweller

Water dweller

Air dweller

Problems with this early system:• Some plants and animals could not be

classified using this system.

• People also used common names.– Common names - don’t describe things

accurately

• Example:

Jellyfish is not a fish

Same common name for different species

Maple Trees = Silver Maple, Sugar Maple, & Red Maple are each different species

Cougar, Mountain Lion, Puma

• By the 1700’s scientists realized that common names were too confusing.

• They vary among languages and even

regions.

Carolus Linnaeus

• Binomial Nomenclature

• “two names”

• All organisms are called by their Genus and species

Canis lupus

Canis latrans

Canis domesticus

How are organisms classified?

Kingdom (6)PhylumClassOrder FamilyGenus Species

• Larger of the two prokaryote kingdoms.• Surrounded by a cell wall made of

carbohydrates.• Wide range of organisms; simple to

elaborate• Range from living in soil to infectious

bacteria.• Such a large range; number of phyla is

debated.

Examples of Eubacteria:• Cyanobacteria (blue-green bacteria)

– Photosynthetic

– Found throughout the world; salt water to freshwater

– Some species survive in hot springs, or in the arctic

– Usually a pioneer species; colonization after volcanoes

• Lack an important carbohydrate found in the cell walls of eubacteria.

• Differ in lipids, ribosomes, and gene sequences.

• Organisms that live in extremely harsh environments- thick mud, digestive tracts, salty environments, and thermal vents.

• Single-celled eukaryotic organisms

• Divided into three groups:– Animal-like protists

– Plant-like protists

– Fungus-like protists

• Examples: amoeba, paramecium, euglena, slime mold

• Build cell walls that do not contain cellulose.

• Heterotrophic- DO NOT CARRY OUT PHOTOSYNTHESIS

Examples: yeast, molds, mushrooms

• Multicellular

• Cell walls contain cellulose

• Autotrophic- can carry out photosynthesis using chlorophyll

Examples: flowering plants, mosses, ferns, multicellular algae

• Multicellular

• Heterotrophic

• Cell membranes/ no cell walls

• Includes incredible diversity

Memorize the levels of classification in order.

• A good way to remember them is……• King Pete Caught Over Five Green Snakes

• Kids Playing Catch On Freeways Get Squished

• You can also come up with your own sentence to help you remember them in order.

• Memorize all 6 kingdoms

The Father of Taxonomy• His system for naming,

ranking, and classifying organisms is still in wide use today (with many changes).

• His ideas on classification have influenced generations of biologists during and after his own lifetime, even those opposed to the philosophical and theological roots of his work.

ClassificationCarolus Linnaeus developed the classification systemHis system was called binomial nomenclatureOrganisms were named using the Latin genus and

species namesAn international committee keeps track of all new

namesA Dichotomous Key is used by scientists to research

new organisms and to figure out scientific names

Kingdom;Animalia

Phylum; Chordata

Class; Mammalia

Order; Carnivora

Family; Ursidae

Genus; Ursus or UrsusUrsus

Species; arctos or arctos

Writing a scientific nameThe scientific name is equal to binomial nomenclatureThe genus and species name are always usedThe genus name is always written firstIt always begins with a capital letterThe species name is written right after the genus name It always begins with a lower case letterBoth words must be underlined or written in italics

Check your answers

1. Animalia

2. Fungi

3. Archaebacteria

4. Protista

5. Plantae

6. Eubacteria

Dichotomous Key

• A dichotomous key is a tool that allows the user to determine the identity of items in the natural world, such as trees, wildflowers, mammals, reptiles, rocks, and fish.

• Keys consist of a series of choices that lead the user to the correct name of a given item.

• "Dichotomous" means "divided into two parts".

Rules when reading a dichotomous key

1. Always read both choices, even if the first seems to be the logical one at first.

2. Be sure you understand the meaning of the terms involved. Do Not Guess.

3. When measurements are given, use a calibrated scale. Do Not Guess.

4. Since living things are always somewhat variable, do not base your conclusion on a single observation. Study several specimens to be sure your specimen is typical.

5. If the choice is not clear, for whatever reason, try both divisions. If you end up with two possible answers, read descriptions of the two choices to help you decide

Dichotomous Key Example

1. a. wings covered by an exoskeleton ………go to step 2 b. wings not covered by an exoskeleton …..go to step 3

2. a. body has a round shape …………….ladybug b. body has an elongated shape ……….grasshopper

3. a. wings point out from the side of the body …….dragonfly

b. wings point to the posterior of the body ……….housefly

• Notice that there were four organisms to be identified and it only took three steps. There should be one less step than the total number of organisms to be identified in your dichotomous key.

Constructing a dichotomous key1. Use constant characteristics rather than variable ones. 2. Use measurements rather than terms like "large" and

"small". 3. Use characteristics that are generally available to the user

of the key rather than seasonal characteristics or those seen only in the field.

4. Make the choice a positive one - something "is" instead of "is not".

5. If possible, start both choices of a pair with the same word.

6. If possible, start different pairs of choices with different words.

7. Precede the descriptive terms with the name of the part to which they apply.