Classifying living things

• Scientists develop system for classifying living things.

– Scientists classify millions of species• 400 years ago organisms were classified on their

appearance and behavior• The problem with this is scientists have realized that

appearances can suggest false connections.• Many things helped change these classifications

– Observing

– Collecting samples

– The microscope

Classifying living things

– Classification and Taxonomy

• Classification is the process of arranging organisms into groups based on similarities

• Taxonomy is the science of naming and classifying organisms.– A good system allows one to

organize a large amount of information

– so it is easy to find and

understand.

Classifying living things

• Using Classification– Similarities and differences among

species are used– Sometimes easy to see like fur, feathers,

or scales– Others more detailed and require DNA

• Taxonomists study Biological relationships

» The Greek word, taxis means arrangement.

» Taxonomists are scientists who classify and name organisms based on their similarities and differences.

Classifying living things

– A Taxon is a group of organisms that share certain traits.

– Taxons can be broad like animals and plants – More specific like cats and roses.

• Taxonomists try to discover how one species evolved as compared with another species.

• Species sharing an ancestor are group together.

Classifying living things

• To determine how to classify, scientists compare a variety of characteristics or traits– A trait is a characteristic or behavior that can be used to

tell two species apart.

– IF two organisms share a trait, taxonomists try to determine if they share the trait because they share an

ancestor.

Classifying living things

– Physical Evidence• All physical evidence helps scientists see that all

living organisms are related by evolution• Primary tools used

– Color– Size– Weight– How group of organisms obtain energy.– The internal structure– And outward appearance

• Comparing skeletons, and fossilized parts

Classifying living things– Genetic Evidence

• In the mid 1950’s DNA helped further classify

• Genetic evidence usually support physical evidence, but not always

• Best example is the red panda and Panda bear– Both ate bamboo,– Both look alike except for

size– DNA proved that the red

panda is more related to the raccoon family

– Pandas more closely to bears

Classifying living things

• Biologists use seven levels of classification

– Carolus Linnaeus developed both a naming system and how to organize them.

• Used appearance to group• This was called the

binomial nomenclature.– Binomial means two

names– Nomenclature means list

of names

• Most of these names are Latin

Classifying living things

– Using scientific names • He used both a genus and

species.• Certain rules for scientific

names must be followed– First letter of the genus (which

comes first) is capitalized

– Species’ first letter is lowercase

– Both written in italics

• These two names are part of a classification system that contains several larger parts.

BINOMIAL NOMENCLATURE

• Uses two names • A GENUS and A SPECIES

– Haliaeetus leucocephalus

• Genus is always CAPITALIZED • Species is always lower case• BOTH ARE IN ITALICS OR UNDERLINED• Just like us, each animal was given 2 names

Latin Binomials

• Canis latrans– Coyote

• Canis lupis– Timber Wolf

• Canis familiaris – Domesticated Dog

Panthera leo– Lion

• Panthera onca – Jaguar

Classifying living things

– Classified into 7 groups• Each group gets narrower

or specific then that last.– Kingdom (most general)

(Animalia- the animals)

– Phylum (Chordata- animals with a backbone)

– Class ( Mammalia- mammals or furry animals that nurse their young.)

Classifying living things

– Order ( Carnivora- carnivores, or animals that kill and each other animals)

– Family (Felidae- cat family)– Genus( Felis housecats, cougars, and many others– Species (catus- all housecats regardless of breed)

• Scientists can compare very broad categories, • As they go down the classification level, you get

more specific, eliminating organism that are not longer similar.

Classifying living things

– Dichotomous keys and field guides help identify• A series of questions that can be answered in

only 2 ways• Your answer to each question leads to another

question with only 2 choices• The questions gradually narrow down the list of

possible organisms.• Field guides also help identify based on physical

characteristics.

Classifying living things

• Classification systems change as more is learned.

– Taxonomy changes as discoveries are made

• First there were 2 groups– Plants

» Green» Non-moving

– Animals

Classifying living things

– Three Domains• Grouping before placing

organism into Kingdoms– Cells containing a nucleus are

called eukaryotic cells– Cells with no nucleus called

prokaryotic cells

• The domain Bacteria and Archae include ONLY prokaryotic cells

• Eukarya contain organisms with eukaryotic.

Classifying living things

• Bacteria- class smaller then Eukarya and have no nucleus

• Archaea- Cells have a distinctive chemistry and can survive extreme environments.

• Eukarya- larger and contain more complex structures

Classifying living things

– Six Kingdoms• After domains, all

organisms fall into one of six kingdoms– Plantae (includes plants,

trees, grass, and moss)– Animalia (animals from lions

to bugs to Multicellular microbes)

– Protista ( organisms that don’t fit easily into animals, plant, or fungi. Either unicellular or have a simple Multicellular structure)

Classifying living things– Fungi (mushrooms, molds and

yeasts)– Archaea ( organisms that are

similar to bacteria but have a cell structure so different they must fit in own kingdom)

– Bacteria (unicellular with no nucleus)

• Changed around 1990 from 5 kingdoms.– Chemical differences between

cells– Protista should be arranged into

smaller kingdoms because of the many differences among its species.

Classifying living things

– Two most familiar kingdoms are plants and animals.

• Plantae– 250,000 plant species known on

Earth.

– Tiny moss to giant kelp

– All plants multicellular

– All plants can make their own food via photosynthesis

– Can not move from place to place

– Can turn to face the sun or light

– Grow upward

Classifying living things• Animalia

– Already a million species in the kingdom

– More then 90 percent are insects

– All animals get energy from other organisms

– Most have some type of mouth and

– A nervous system– Has no cell wall like

plants

Classifying living things

– Other organisms in remaining 4 kingdoms• Protista

– Has a wide variety of organism– Most unicellular– Have large complex cells with

true nucleus (eukaryote)– Some eat other organisms– Some can photosynthesize– Do not have specialized cells

like plants, animals, or fungi– Most live in fresh or salt water

Euglena sp.

Classifying living things• Some organisms,

like seaweed are also classified as Protista

• Fungi– Composed of

molds, yeasts, mushrooms

– Take in nutrients from their surrounding

– Remain rooted in one place

– Many fungi act as decomposers

– Don’t photosynthesize

Classifying living things

• Archaea– Mid 1990’s changed

classification of bacteria– Do not have a nuclei– But cell structure is different

from that of bacteria– Live in water environments– Live in extreme environments

like boiling mud near geysers, Hot vents, bottom of oceans, salt ponds, deep in sand

Classifying living things

• Bacteria– Live just about

everywhere.– Most are helpful– Some harmful– All unicellular– Have small cells without a

nucleus– Have a cell wall but not

the same as plants