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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