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Biology 11
Classification Unit Notes
1
Basics of Classification (Taxonomy)
The earth today is home to more than 300,000 species of plants and more than one million species of
animals. Biologists, called taxonomists, have developed a way to organize all these species. One of the
most important 18th century naturalists was a Swedish botanist and medical doctor named Karl von Linné.
He wrote 180 books mainly describing plant species in extreme detail. Since his published writings were
mostly in Latin, he is known to the scientific world today as Carolus Linnaeus, which is the Latinized
form he chose for his name.
Linnaeus's basic system is still used today and is the foundation of modern taxonomy. The term
“classification” is synonymous with the word “taxonomy.” Taxonomy is the study of the classification of
organisms.
The classification system places an organism into
“groups” called taxonomic levels” based on various
criteria. The taxonomic levels start with the most
broad category and narrow down until only a single
species. The order of the taxa from broadest is:
Kingdom
Phylum
Class
Order
Family
Genus
Species
The generally accepted criterion for defining a species is that organisms of the same species interbreed
under natural conditions to yield fertile offspring. Individuals of different species normally do not
mate. If they are forced to mate, the mating is either unsuccessful or the offspring are sterile. For example,
a horse (Equus caballus) can be mated to a donkey (Equus assinus), and the result will be a mule.
However, mules are sterile and cannot reproduce. Thus, the horse and donkey are classified as different
species. A quarterhorse and a thoroughbred can mate and produce a fertile offspring. Therefore, both are
classified as the same species: Equus caballus.
Linnaeus developed a two-name naming system is known as “Binomial nomenclature” (Latin for 2 name
naming system). We call this name the “scientific name” of the organism. For example, humans have the
scientific name Homo sapiens. The name of any species is two words: the name of the genus followed by
the “species modifier.” For humans, Homo is the genus and sapiens is the species modifier. The genus
name is generally a noun, while the species modifier is an adjective. Thus, Homo sapiens means “human
knowing.”
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Classification Unit Notes
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So why Latin?
Latin is used in nomenclature (and throughout Science) for a number of reasons:
1) Latin provides a common language for all scientists, regardless of their country of origin and first language.
2) Latin is a DEAD LANGUAGE. This means that no country speaks it as a primary mode of communication.
When languages are not spoken, they do not evolve and change. All other modern languages are constantly
changing due to the addition of new words, cultural shifts and generational phrases and lexicon. Common
word meanings today may mean something slightly or even vastly different in the future. Consider the word
“bad”. Historically is meant something “no good”. Today, it can be used in street cultures to mean
something “very good”.
3) Common names can be very confusing as different countries or areas may use the same common names to
describe different species. Another familiar problem occurs when a species has more than one
common name. For example, the striped mullet, Mugil cephalus, is found all over the world, and
has a variety of common names (striped mullet, black mullet, sea mullet, flathead mullet, and gray
mullet) which are used in different regions.
Examples of Taxonomic Comparisons
Man
Box Elder Tree
Bobcat
Canadian lynx
Kingdom
Animalia
Plantea
Animalia
Animalia
Phylum/Division
Class
Order
Family
Genus
Species
Chordata
Anthophyta
Chordata
Chordata
Mammalian
Dicotyledonae
Mammalia
Mammalia
Primates
Sapindales
Carnivora
Carnivora
Hominidae
Aceracae
Felidae
Felidae
Homo
Acer
Lynx
Lynx
sapiens
nugundo
rufus
canadensis
The more taxa two organisms have in common, the more closely related the two organisms are. Using the
table above, which two organisms are most closely related? How closely related are they? Which organism is
LEAST related to the others? How do you know?
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Classification Unit Notes
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The 6 Kingdoms of Life
Name
1
2
3
Archaeabacteria
Characteristics and Examples
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Eubacteria
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Protista
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Fungi
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Plantae
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Animalia
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Prokaryotic (no membrane-bound nucleus)
Unicellular
Anaerobic organisms (can’t live in oxygen)
Three subdivisions:
 Methanogens – methane producers
 Halophiles – salt lovers, can thrive in salt
concentrations 10x that of sea water
 Thermoacidophiles – thrive in 100oC +
temperatures and highly acidic conditions.
Prokaryotic
Unicellular
Can be either autotropic or heterotrophic
Reproduce asexually through binary fission.
Three main shapes:
 Round = cocci (coccus – singular)
 Rod shaped = bacilli (bacillus)
 Spiral = Spirullus
Eukaryotic (true membrane-bound nucleus)
Unicellular (some in colonies)
Live in aquatic environments
Three examples:
 Amoeba – moves on pseudo pods
 Paramecium – moves with cillia
 Euglena – moves with flagella
Eukaryotic (true membrane-bound nucleus)
Both Unicellular (yeast) and multicellular
(mushrooms, mould, etc.)
Heterotrophs – must eat something else. Fungi
break down food outside their body and absorb
the nutrients.
Three examples:
 Mushrooms, molds, mildews, yeast, etc.
Eukaryotic (true membrane-bound nucleus)
Mostly multicellular
Autotrophs – contain chlorophyll and carry out
photosynthesis where they convert sunlight into
sugars.
Examples:
 Mosses, grass, flowering plants, trees, etc.
Eukaryotic (true membrane-bound nucleus)
Multicellular
Heterotrophs – must eat something else.
Most reproduce sexually
Examples:
 Sponges, insects, birds, mammals,
humans, etc.
Pictures of Representative
Organisms
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Biology 11
Classification Unit Notes
Phylogenetic Tree
Most scientists believe that organisms have changed
over time. The history of the evolution of organisms is
called phylogeny. Relationships between organisms
are often shown on a diagram called a Phylogenetic
tree.
The tree begins at the bottom with the most ancestral
form and includes branches that lead to all of its
descendants.
Types of Symmetry
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The 9 Phyla of Kingdom Animalia
Phylum Name
1
Porifera
Characteristics & Examples
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2
Cnidaria
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3
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Platyhelminthes
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4
Nematoda
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5
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Annelida
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The Sponges
Sessile-stays in one place
Most simple multicellular organism
No tissues or organs
Central body cavity
Osculum- large opening(s) at top
Pores for allow water in and out
About 5000 species in this group
Jellyfish & Anemones
Nematocytes- stinging cells on tentacles
Radial symmetry
Gastrovascular cavity- central body cavity
Mostly marine (ocean creatures)
Jellyfish are considered plankton (free
floaters) in the ocean.
Anemones and hydra are sessile.
About 10 000 species in this group.
“Flat Heads”
These are flat worms
Bilateral Symmetry
Diffusion is used in place of important
body systems.
No real vision only senses light with
eyespots
Only one food opening. Food enters the
mouth, is digested and absorbed, then
wastes are released from the same opening.
About 19 000 species in this group.
Examples: Planaria, Flukes and
Tapeworms
Roundworms are found everywhere
Cylindrical, slender, tapered and both ends
Bilateral symmetry
Many Nematodes are parasitic
1st group with a continuous digestive tube
Hookworms are intestinal and drink blood
from the stomach
About 20 000+ species in this group
Examples – Ascaris, hookworm, pinworms
Segmented worms are capable of more
complex movements
Have a closed circulatory system with 5
pairs of aortic arches (like “hearts”)
Food passes into the mouth, travels along a
continuous tube and then exits the anus.
Mass of nerves forms simple “brain” called
a ganglion.
About 12 000+ species in this group
Examples – Earthworm, leeches, etc.
Pictures of Representatives
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Arthropoda
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Classification Unit Notes
Insects, spiders (arachnids) and
crustaceans (lobsters, crabs, shrimp,
etc.)
Most dominant animals on Earth
Exoskeleton “suit of armor” made of
chitin
Efficient gas exchange allows rapid
supply of oxygen to muscles
Jointed appendages (6+ legs)
Well developed sensory system
Well developed nervous system
Well developed circulatory system
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 About 1 000 000+ species in this group
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The “shell fish” + squid/octopus
Shell made of Calcium Carbonate
Muscular foot
Mantle lays down the shell
About 100 000+ species in this group
Mollusca
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Echinodermata
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Chordata
 The name echinoderm is Greek for
“hedgehog skin”
 Use a water-vascular system for
locomotion (tube-feet),
 Radial symmetry (pentamerous – 5
sided)
 They can regenerate parts of their body
that are damaged or “broken off”.
 About 7000 species in this group
 Dorsal nerve (Spinal) cord
 Notochord or backbone/vertebrae
 Tail (at some stage of the life cycle)
 Gill Slits (at some stage of the life
cycle)
 About 7000 species in this group
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Classification Unit Notes
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The 7 Classes of Phylum Chordata
All chordates have a number of structures in common:
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A notochord (noto = the back; chord = string) is present in all embryos, and may be present or
absent/reduced in adults. This is the structure for which the phylum was named.
A dorsal, hollow, nerve cord.
The pharangeal slits (pharynx = throat), also known as gill slits, originally functioned in filter
feeding: water is taken into the mouth and let out via the pharangeal slits. The slits filter out food
particles and keep them in the animal’s body so they can be put into the digestive tract. In fish, these
have become modified as gills, and in humans as our ears and eustachian tubes.
A postanal tail (post = behind, after; anal refers to the anus) is present and extends behind the anus
in many taxa, thus the anus isn’t at posterior tip of body. In humans, the tail is present during
embryonic development.
Chordata Phylogenetic tree
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Classification Unit Notes
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The 7 Classes of Phylum Chordata
Phylum Name
1
Agnatha
2
Chondrichthyes
Characteristics & Examples
 Class Agnatha (a- = not, without;
gnatho = jaw);
 They do not have jaws, are eel-shaped,
prey on fish;
 Examples: lampreys and hagfish.
 Class Chondrichthyes (chondro =
cartilage; ichthys = fish)
 They have a cartilage skeleton, not
bone.
 They are not buoyant like other fish so
they must swim or sink.
 Like other fish they have a lateral line
system which detects differences in
water pressure, the equivalent of our
hearing.
 Examples: sharks and rays.
 Class Osteichthyes (osteo = bone) is
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Osteichthyes
the bony fish.
 This is the most numerous of all
vertebrate classes.
 2 chambered heart
 Two subdivisions:
o
o
Lobe finned fish
Teleosts (you are most familiar with
these)
 Class Amphibia (amphi = on both
4
sides, double; bios = life)
 They were the first land vertebrates.
 3 chambered heart
 External fertilization takes place in
Amphibia
water.
 They are tied to the water due to this &
the fact that their skin must remain
moist or risk drying out.
 Examples: frogs, newts, and
salamanders.
Pictures of Representatives
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Reptilia
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Aves
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Mammalia
Classification Unit Notes
Class Reptilia (reptili = creeping)
Reptiles have scales and are dry to the
touch.
Their eggs have leathery shells and do
not require water.
3.5 chamber heart
Reptiles are exothermic (exo = out,
outside), that is they maintain their
body temperature through external
means such as sunning on a rock or
seeking shade.
Examples: dinosaurs (dino = terrible),
snakes, turtles, crocodiles, and lizards.
 Class Aves (avi = a bird) the birds.
 They have feathers for insulation and
flight.
 Birds’ bones are hollow and light
weight for flight.
 Birds are endothermic (endo = within,
inner), that is, they control their body
temperature from within (they’re
“warm-blooded”).
 Birds have shelled eggs and so must
have internal fertilization — the egg
must be fertilized before the hen’s
reproductive tract secretes an eggshell.
 Examples: parrots, ducks, eagles.
 Class Mammalia (mamma, mammil
= teat, nipple) are the mammals.
 They have fur/hair;
 They have mammary glands which
produce milk for the young.
 They are endothermic.
 Most mammals bear live young
 3 Subdivisions:
 Monotremes (trema = hole)
includes the platypus and spiny
anteater. These mammals lays eggs
like reptiles, but do have fur and
milk. However, they have no nipples:
their mammary glands just secrete
milk onto the fur, from which the
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Biology 11
Classification Unit Notes
babies lick it. E.g. platypus and spiny
ant-eater
 Marsupials (marsupi = a bag,
pouch) includes opossums,
kangaroos, koalas, etc. The young are
born as very immature embryos and
must crawl to their mother’s pouch to
continue their development.
 Placentals (placent = a round, flat
cake) contains most of the animals
with which we are familiar. In this
taxon, young complete embryonic
development within the mother’s
uterus and are nourished across a
placenta.
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Biology 11
Classification Unit Notes
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Dichotomous Keys
A tool used to help you identify various organisms. For example, if you were asked to find the names of the
creatures below, you could use a dichotomous key to help you.
1a If fish shape is long and skinny ………………………………………………………………………………………. go to step 2
1b If fish shape is not long and skinny, ………………………………………………………………………………. go to step 3
2a If fish has pointed fins,……………………………………………………………………………………………………..it is a trumpet fish
2b If fish has smooth fins, …………………………………………………………………………………………………….it is a spotted moray eel
3a If fish has both eyes on top of the head, …………………………………………………………………… go to step 4
3b If fish has one eye on each side of the head, ……………………………………………………………. go to step 5
4a If fish has long whip-like tail, …………………………………………………………………………………………it is a spotted eagle ray
4b If fish has short, blunt tail, ……………………………………………………………………………………………it is a peacock flounder
5a If fish has spots, …………………………………………………………………………………………………………….. go to step 6
5b If fish does not have spots, …………………………………………………………………………………………. go to step 7
6a If fish has chin "whiskers," ……………………………………………………………………………………………it is a spotted goat fish
6b If fish does not have chin "whiskers," ………………………………………………………………………….it is a band-tail puffer
7a If fish has stripes, …………………………………………………………………………………………………………….go to step 8
7b If fish does not have stripes,………………………………………………………………………………………… it is a glassy sweeper
8a If fish has a v-shaped tail, ………………………………………………………………………………………………..it is a squirrel fish
8b If fish has a blunt tail, ……………………………………………………………………………………………………….it is a glass-eye snapper
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Classification Unit Notes
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Classification Flow Chart
Name the following creatures using the flow chart below:
1
2
3
4
5
6
7
8
9
10
All Creatures
Wheels for feet
1 wheel
No Wheels
Flipper feet
4 wheels
No Flipper feet
Wheelus quatros
2 feet
2 arms
4 arms
4 feet
Noflipus bipedus Noflipus quatrpedus
Monowheelus diarmus Monowheelus tetrarmus
Noflipus octopedus
2 eyes
Snake-like tail
Dieyous serpentailus
8 feet
3 eyes
Fish-like tail
Dieyous poisontailus
2 arms
trieyous diarmus
4 arms
trieyous tetrarmus