Classification
Since the earliest of times people have been classifying living
things. As recently as the 1960’s, biologists simply classified all
living things into two groups – plants and animals. Today living
organisms are classified into 5 main groups.
In this topic we will look at how organisms are classified and how
and why we name organisms .
But First …….what is Life?
 You know that a horse is alive and that your
text book is not. However it is not always
obvious whether something is alive or not.
 To try and work out whether something is
living or not, Biologists use a list of
characteristics that living organisms ( a living
thing) must exhibit.
 All Living things
exhibit the following
characteristics
 Remember MRS
GREN …….
What is Classification?
 Classification in Biology is arranging living
organisms into groups.
 This is called TAXONOMY.
 There are many advantages gained by
classifying organisms.
 - Species identification
 - Predictive value- if this shows this then …
 - Evolutionary links
Why are organisms organised into
groups?
 TAXONOMY makes it easier to identify, describe and
remember different groups of organisms
 Every organism needs an international name.
 Organisms are organised depending on their
characteristics.
 Organisms with similar characteristics are grouped
together.
 The more characteristics they share, the more select
the organisational group
Binomial names
 Binomial names are internationally
recognised names for each organism.
 You have to remember at least 2…
 They are the Genus and the species names
 Note that the Genus always has a capital
letter and the species has a small letter.
They are usually underlined and/or in italics.
Organisational groups - who is
responsible??
 It was the Swedish biologist Carl
Linnaeus who devised a
systematic method of naming
organisms. It was called the
Binomial System and is still
used today.
 All organisms are divided into the
following TAXA
The classification system recognises
7 taxa, which we use today
 Kingdom
 Phylum
 Class
 Order
 Family
 Genus
 Species
Kingdoms
 Taxonomists do not always agree about how
living organisms should be classified into
kingdoms. One system that is widely used
has 5 kingdoms.
-Prokaryote/ Monera - includes all types of bacteria
-Protictista – unicellular organisms like amoeba & algae
-Fungi – the moulds & the yeasts
-Plantae – mosses, ferns, conifers & flowering plants
-Animalia – all animals
Kingdom
 A kingdom is a group of closely related phyla
 We study TWO of the kingdoms in our IGCSE
course
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The Animals kingdom
The Plants kingdom
 The animal kingdom includes organisms from
humans to worms
 Eg man belongs to the Kingdom : Metazoa
Phylum
 A phylum is a group of closely related
classes
 Man belongs to the Phylum: Chordata
(meaning backbone)
 Another phylum is invertebrates
Class
 A class is a group of closely related orders
 The vertebrate phylum is divided into 5 classes:
 Fish
 Amphibians
 Reptiles
 Birds
 Mammals
 For your syllabus, you need to know the
characteristic features of each class
Order
 An order is a group of closely related
families
 Man belongs to the Order: Primates
 Primates have a thumb that can be opposed
to the other digits, binocular vision and
various more broadly defined characteristics
(including high intelligence)
Family A family is a group of closely related Genera
 Man belongs to the Family: Hominidae
Genus
 A genus is a group of closely related species
 The genus is the first part of the binomial
name of an organism – this describes the
final two levels of organisation.
 Man belongs to the Genus: Homo
Species
 This is the final basic unit of classification.
 A species is defined as a group of organisms
that can reproduce with each other to
produce fertile offspring.
 This means that if a horse and donkey
reproduce to make a mule but the off spring
(the mule) cannot reproduce itself (which it
can’t!) then horses and donkey’s must be
different species
Species
 Man belongs to the species:sapiens
(note the
small letter and italics of sapiens)
 The species name is the second part of the
binomial name.
 Human: Homo Sapiens
 Look at the next slide showing the
classification of a lion………
The variety of life…..
 There are millions of different plants and
animals in the world.
 They may differ in their appearance, their
behaviour or where they live.
 We can divide living things up into groups.
 For your course you need to know about 2
main groups
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the Vertebrates and
the Invertebrates.
Vertebrates
 These are animals with a backbone.
 There are five groups of vertebrates:
 Amphibians
 Birds
 Fish
 Mammals
 Reptiles
Fish
 Wet Scaly covering
 Live in water all their
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lives
Have gills for breathing
Eggs laid in water
Cold blooded
e.g. shark, cod, eel
Amphibians
 Have a smooth moist skin with no scales
 They breed in water - External fertilisation.
 Eggs are laid in water
 Young have gills for breathing and live in the
water
 Adults have lungs and live on land but can
swim well
 Cold blooded
 e.g. frog, toad
Reptiles
 Dry, waterproof skin with
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scales
Most live on land but some
can swim
Have lungs to breathe air
Some have 4 legs but
some slide along the
ground
Internal fertilisation
Eggs have a soft leathery
shell
Cold blooded
e.g. snake, crocodile,
lizard
Reptiles
Birds
 Covered with feathers
 Live on land and in the air
 Have wings for flying and a
beak for feeding- most are
able to fly
 Internal fertilisation & parental
care
 Eggs have a hard shell
 Warm blooded
 e.g. owl, vulture, sparrow
Mammals
 Covered with hair/fur
 Young develop inside the
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mother- internal fertilisation
Young are fed on milk produced
by mammary glands of mother
Live on land, in water and in the
air
Have lungs
Warm blooded
e.g. dog, lion, YOU!
Summary of Vertebrates
Invertebrates
 These are animals NO backbone
 There are eight groups of invertebrates
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Molluscs
Flatworms
Annelids
Roundworms
Sponges
Echinoderms
Cnidarians
Arthropods – you only need to know about this one !
Arthropods
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This is the largest group of invertebrates
They have jointed legs
Their bodies are divided into segments
They have a hard skeleton on the outside
called an exoskeleton
 When they grow they moult.
 On their heads are feelers or antennae.
 The arthropods are made up of 4 smaller
groups
Insects
 The largest group within the arthropods
 3 pairs of legs (6 in total).
 One pair of antennae.
 Body is divided into 3 parts (head, thorax,
abdomen).
 Usually 2 pairs of wings
 e.g. grasshopper
Arachnids
 4 pairs of legs and No
wings
 Bodies divided in to 2
parts
 No antennae
Mouthparts have
pincers
 e.g. spider
Crustaceans
 Quite a lot of legs
(between 5 and 8 pairs)
 Two pairs of antennae
 Mainly live in water,
breathe oxygen using
their gills (woodlice is an
exception)
 e.g. crab
Myriapods
 Have long bodies made up
of many segments
 Lots of legs (over 8 pairs –
but can be as many as 750
legs! – depends on how
many segments they have.
 One pair of antennae
 e.g. centipede – carnivore
 eg. Millipede - herbivore
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(not officially on your syllabus!)
Test!
 See if you can identify the class of these
organisms
 They were all recently discovered in Vietnam
Green flash
Green flash – a reptile
 The Annamite mountains of
central Vietnam are providing
scientists with a torrent of new
and exciting species, such as
this tree viper.
 The environmental group WWF
is showcasing some of the new
discoveries this week. It says
forests in the region are crucial
for local indigenous peoples as
well as wildlife.
The skipper
The skipper – an insect
 One of the smallest of the
new finds is this butterfly, a
"skipper" of the Zela genus.
 Typified by a quick, darting
flight, skippers differ
anatomically from other
butterflies, most noticeably
by having antennae that
sweep backwards at the
ends.
White moustache
White moustache – a reptile
 The white-lipped keelback
(Amphiesma leucomystax) is
found across more of Vietnam
than just the central Annamites.
 The name means "white
moustache" or "white upper lip",
and this specimen clearly lives
up to its name.
 It tends to live beside streams
where it makes meals of frogs
and other small animals.
Loris
Loris – a mammal
 The group of species
collectively known as the slow
loris is threatened from various
directions.
 Used for food and in traditional
medicine, and with their forest
habitat dwindling in many parts
of southeast Asia, perhaps the
biggest issue is the pet trade.
Creatures so cute are bound to
be in demand, but often do not
survive transit in captivitity.
Slackjaw
Slackjaw – a reptile
 WWF describes this part of the
Annamite range as the Green
Corridor. It is home to
endangered reptiles,
amphibians, birds and primates.
 Local authorities say they are
committed to conserving the
region's natural resources; but
as in other parts of the world,
logging, hunting, and human
development are all putting
pressure on the wildlife.
Dichotomous keys
 Dichotomous keys are a way of identifying
organisms.
 They work by asking a sequence of
identification questions, each with multiple
answers.
 Choosing one of the answers leads you on to
the next step.
 Eventually you can identify your organism.
Try this one !!
Dichotomous keys
 Look at these pictures
of birds
1
2
3
4
 They are all fairly
similar
 A Dichotomous key
will help to identify
them.
Finch Dichotomous key
Finch Identification
1.
2.
3.
a. The beak is relatively long and slender.
Certhdea sp.
b. The beak is relatively stout and heavy.
Go to set 2
a. The bottom surface of the lower bill is flat
and straight.
Geospiza sp.
b. The bottom surface of the lower bill has a
bend
Go to set 3
a. The lower edge of the upper bill has a
distinct bend.
Camarhynchus sp.
b. The lower edge of the upper bill is mostly
flat.
Platyspiza sp.
Finch Dichotomous key
 Use the key to identify the birds.
 Answers are below…
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Certhdea sp = Bird 4
Geospiza sp = Bird 3
Camarhynchus sp. = Bird 1
Platyspiza sp. = Bird 2
Dichotomous keys
 Now work through the examples in your work
books.
 Complete for homework
Shortpants
Morgan
Smith
Elsworth
Hickson
Hickman