Classification of Earth’s
Diversity
Biodiversity
• Biodiversity – the variety of
organisms on earth is the result of
3.5 billion years of evolution
• Approx 8 million species on earth!
• To make sense of all of them, they are
organized into meaningful groups
• Species are becoming extinct at an
increasing rate, so there is a rush to
catalog them
Common vs Scientific Names
• Common names are convenient, but there
are problems:
- same names are used for different species
(robin here, robin Europe)
- can be more than one name for same
species (mt lion, cougar, puma)
- very ambiguous (not very descriptive)
Common vs. Scientific Names
• Advantages of scientific names:
– Provide a consistent naming system for
all
– Show evolutionary relationships
– Systematics – the science of naming and
grouping organisms according to biological
meaning
– Groups are called taxa (singular: taxon)
Binomial Nomenclature
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Bi = two, nomial = name
Scientific names have two parts
Always typed in italics (or underlined)
First word is capitalized, second is not
First word - genus – a group of similar
species
• Second word - species – unique to
ONLY that species
Use Latin language
Brown bear
Polar bear
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Ursus arctos
Ursus americanus
Ursus maritimus
Ursus thibetanus
Black bear
Asian black bear
Linnaean Classification
• Carolus Linnaeus developed 1st
system
• Four levels of hierarchy, or ranks
• Today there are 7: Kingdom, Phylum,
Class, Order, Family, Genus, Species
• Bears belong in the Family Ursidae
• Pandas are also in this Family, but have
a different genus (Ailuropoda)
• Mnemonic for remembering
• King Phyl Came Over For
Good Spaghetti
Kingdom- Ex: p.514
• Largest and most inclusive taxon
• All multicellular animals are in the
kingdom Animalia
Phylum
• Contains groups of organisms that are
different but share important characteristics
• Phylum Chordata features organisms with a
nerve cord along the back
• Within the phylum, are groups called
Classes…
Class
• Classes are groups that narrow down the
differences even further
• Class Mammalia includes all animals that are
warm-blooded, have body hair, and
produce milk for their young
• Within a class are groups called orders…
Order
• Order Artiodactyla contains hoofed
animals with an even number of toes
• Within an order are groups called
Families
Family
• Family – a group of several genera
(plural of genus) that share similarities
• Bactrian camel and dromedary more
closely related than the llama (Family
Camelidae)
Genus species
• Camelus bactrianus – two humps
• Camelus dromedarius – one hump
• The genus Camelus includes both of
these species
Identifying Organisms
• Dichotomous keys
NOT like these
• Used to VISUALLY identify organisms
• Has series of “couplets” or paired statements
that describe visual traits (color, size, unique
features, etc.)
• Each statement describes the presence or
absence of a visible trait
• Each set of choices helps to narrow down the
identity of the organism
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DIRECTIONS:
The most useful tool for such identifications is the
dichotomous key, which contains information useful in
identifying similar kinds of organisms, but is arranged in a
way that allows the information to be used quickly.
A dichotomous key is a list of paired statements (each
statement is called a lead) that guides you to the identification
of a specimen.
The paired leads (the pair of leads together is called a couplet)
are contrasting descriptions of certain characteristics.
In a good key, couplets are written so that you must choose
one or the other of the leads as being true for your specimen.
Couplet leads should always be mutually exclusive
In addition, the leads in a couplet should be parallel; that is,
both should ask questions about the same character(s).
Can you figure out the key?
• Help! Scientists have discovered quite a few
new creatures on planet Pamishan. They
need your help to identify and classify
them. Use the dichotomous key on the next
page to identify these creatures.
• ALWAYS start with step 1, and go to
whichever step the key tells you