CLASSIFICATION
Why Do We Classify?
• We classify in order to
organize.
• We classify to
recognize
relationships among
organisms.
• We classify to study
the evolutionary
history of organisms
(phylogeny).
History of Classification
• Aristotle was a Greek
philosopher and
scholar.
• Divided organisms
into 2 groups - plants
and animals.
• Divided animals into
groups based on
number of legs.
• Divided animals into 3
groups according to
how they moved walking, flying, or
swimming (land, air,
or water)
History of Classification
• Carolus Linnaeus was a
Swedish scientist.
• Classified plants and
animals according to
similarities in form.
• Divided living things into
one of two "kingdoms" –
Plant or Animal
• Divided each of the
kingdoms into smaller
groups called "genera"
(plural of "genus").
• Divided each genera into
smaller groups called
"species“.
The Evolution of Our
Classification System
• The Linnaean System is used by scientists all over
the world, but has been expanded to include new
and different living things as they are discovered.
It will continue to grow as human knowledge
grows.
Classification Terminology
• CLASSIFICATION –
• Grouping things based on
their similarities.
• TAXONOMY –
• The science of classifying
organisms.
• ORGANISM –
• Any living thing.
• BINOMIAL
NOMENCLATURE –
• A two-part scientific name
(Genus species).
• EVOLUTION –
• Species change gradually
over time.
Our Current
Classification System
• The classification
system in use
today places each
living thing into a
series of specific
groups based on
similarities and
differences in body
structure, color,
behavior, etc.
Our Current
Classification System
• The largest group
into which any
living thing can be
classified is its
kingdom.
• This is followed by
its phylum or
division, then its
class, order, family,
genus, and finally
its species.
The Kingdoms
• Most biologists use
a classification
system based on
five kingdoms.
The Kingdom Debate
• The number of
kingdoms is often
under debate,
depending on how
scientists interpret
current research.
• For example, some
scientists separate
the Moneran into
two kingdoms.
Our Hierarchical System
• Taxonomists divide
organisms into a
series of groups
(divisions) that get
more and more
specific.
• The most general
division of life is a
kingdom.
• The most specific
division of life is a
species.
Our Hierarchical System
• Within each kingdom, there
are groups, increasing in
commonality and
evolutionary relationships,
but decreasing in size (fewer
numbers).
• For example, two organisms
in the same order have more
in common than two
organisms in the same class.
Moneran Kingdom
• Bacteria are among the oldest living organisms
on Earth, and are very small.
• Because the bacteria structure is so minute, it can
only be seen through a microscope.
• Bacteria are unicellular prokaryotes.
• Bacteria is commonly found in the ground, water
and in other living organisms.
• Most bacteria are
heterotrophs but some
bacteria like blue-green
algae are autotrophs.
Moneran Kingdom
• While some types
of bacteria can
cause diseases and
become harmful to
the environment,
animals and
humans, others
offer benefits that
we likely could not
live without.
Harmful Bacteria
• Some types of
bacteria can attack
plants, causing
diseases like leaf
spot and fire
blight.
Harmful Bacteria
• In human hosts, certain
types of bacteria can cause
tetanus, pneumonia,
syphilis, tuberculosis and
other illnesses.
• Humans can be treated
with antibiotics, which kill
bacteria or at least hamper
their growth.
• Antiseptics, sterilization
and disinfectants can help
prevent contamination
and risk of infection from
bacteria.
Helpful Bacteria
• The term “friendly
bacteria” is used to
describe the types of
bacteria that offer some
benefit.
• Not only does bacteria
help produce the food we
eat and keeps the soil
fertile, it also helps us
digest our food.
• Bacteria in our digestive
system help to convert
milk protein into lactic acid
and inhibit the growth of
potentially harmful
bacteria.
Archaebacteria vs. Eubacteria
• Archaebacteria
– “ancient bacteria”
– Found in very harsh
conditions such as in
the volcanic vents or at
the bottom of the sea.
– They survive in the
environments such as
sea vents releasing
sulfide-rich gases, hot
springs or boiling mud
around volcanoes.
– “extremophiles”
– All forms of
archaebacteria are nonpathogenic.
• Eubacteria
– “true bacteria”
– Cyanobacteria – bluegreen algae
– Most bacteria are in this
kingdom.
– They are the kinds
found everywhere and
the ones people are
most familiar with.
Archaebacteria vs. Eubacteria
Protozoan Kingdom
• This is sometimes called
the “odds and ends”
kingdom.
• A protist is any organism
that is not a plant, animal
or fungus.
• Mostly unicellular, some
are multicellular (algae)
• Can be heterotrophic or
autotrophic.
• Most live in water
(though some live in
moist soil or even the
human body).
• ALL are eukaryotic (have
a nucleus).
Classification of Protists
• How they obtain nutrition
• How they move
• Animal-like Protists - protozoa
- heterotrophs
• Plantlike Protists - algae
autotrophs
• Fungus-like Protists –
heterotrophs & decomposers
Fungi Kingdom
• Mushrooms
• Molds
• Yeasts
• Mildews
Fungi Kingdom
• Most fungi are
multicellular (yeast
is unicellular).
• All fungi are
eukaryotic
heterotrophs.
• Fungi can be found
almost everywhere
on land, but only a
few live in fresh
water.
The Importance of Fungi
• Fungi are some of the most
important organisms in terms of
their ecological and economic
roles.
• By breaking down dead organic
material, they continue the
cycle of nutrients through
ecosystems.
• Most vascular plants could not
grow without the fungi that
inhabit their roots and supply
essential nutrients.
• Other fungi provide numerous
drugs (such as penicillin and
other antibiotics), foods like
mushrooms, truffles and morels,
and the bubbles in bread,
champagne, and beer.
• A number of fungi, in particular
the yeasts, are important
"model organisms" for studying
problems in genetics and
molecular biology.
Bad Fungi?
• Fungi also cause a
number of plant and
animal diseases.
• In humans, ringworm,
athlete's foot, and
several more serious
diseases are caused by
fungi.
• Plant diseases caused
by fungi include rusts,
smuts, and leaf, root,
and stem rots, and
may cause severe
damage to crops.
Plant Kingdom
• Plants are
multicellular
eukaryotes.
• Plants are autotrophs
and make their own
food through the
process of
photosynthesis.
• Plants feed almost all
of the heterotrophs on
Earth.
Plant Kingdom
Animal Kingdom
• All animals are
multicellular
eukaryotes.
• All animals are
heterotrophs.
• Animals have
adaptations that
allow them to find
food and digest it.
• Members of the
animal kingdom are
found in diverse
environments on
earth.
Animal Kingdom
Animal Kingdom
Invertebrates
Vertebrates
The Evolution of the
Animal Kingdom
The Organization of Life . . .
. . . ever changing!