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 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 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

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 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

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

Molluscs Flatworms Annelids Roundworms Sponges Echinoderms Cnidarians Arthropods – you only need to know about this one !

Arthropods

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

(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

They are all fairly similar

A Dichotomous key will help to identify them.

1 2

3 4

Finch Dichotomous key    Finch Identification

1. a. The beak is relatively long and slender. Certhdea sp.

  b. The beak is relatively stout and heavy. Go to set 2

     

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

 

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…

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

Morgan

Smith

Hickson

Shortpants

HickmanElsworth