Download worksheet: classifying mammals

TWENTY FIRST CENTURY SCIENCE
KEY STAGE 3 TO KEY STAGE 4
Classification of mammals
Mammals are vertebrates which share a set of common characteristics. The list
below describes properties that mammals have in common, but there are
exceptions.
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Mammals are covered in hair or fur
They are warm blooded
They give birth to live young
Females produce milk to suckle their young when they are born
Most mammals live on land
They have four limbs
In the boxes below are descriptions of some common mammals.
Lion
Carnivore
Fur covered
Warm blooded
Live on land
Gives birth to live young
Mother suckles infants
Powerful limbs, sharp claws
Elephant
Herbivore
Body covered in fine sparse hair
Warm blooded
Lives on land
Gives birth to live young
Mother suckles infants
Sturdy limbs with sponge-like feet
Beaver
Herbivore
Fur covered
Warm blooded
Lives mainly in water but also on land
Gives birth to live young.
Mother suckles infants
Short front paws with large claws, and larger
back legs with webbed feet
Dolphin
Carnivore
Body covered in thick tough skin
Warm blooded
Lives entirely in water
Gives birth to live young
Mother suckles infants
Two short front flippers, and a dorsal fin on its
back
To do
Draw a table in your book with the following headings. Use the descriptions of the
four mammals to complete the table with the correct characteristics:
Characteristics that
mammals share with other
vertebrate groups
Characteristics that most
mammals have, but which no
other vertebrate group have
Characteristics that all mammals
have, but which no other
vertebrate group have
Do you think four animals is a large enough sample to study to come up a definite
set of characteristics?
Case study by Helen O’Connor from Preston Manor High School, Wembley
© in this format University of York and Nuffield Foundation 2008 • downloaded from www.21stcenturyscience.org
What characteristics do dolphins have which mean they are characterized as
mammals and not fish?
What kind of animal is the duck-billed platypus?
To study
The duck-billed platypus was first described in 1797. This account
described a small fur-covered animal with webbed feet and a beaver-like
tail. The head has a flat beak like a duck. The body shape is similar to a
crocodile, with short legs spread out to the sides. It lives in both water and
land. It has webbed feet for efficient swimming; long sharp claws on the
feet help it burrow out a den. The duck-billed platypus lays soft-shelled
eggs like those of a lizard. But when the young hatch out of their eggs, the
platypus babies drink milk produced by their mothers.
When scientists first read about this strange new animal, they didn’t believe
it. Sailors often returned from abroad with wild stories about dragons and
other monsters.
However, when a respected biologist dissected a pair of duck-billed
platypus specimens, preserved by pickling, the scientific world was stunned
to learn that it was a genuine animal. Scientists had difficulty believing
there was an animal that could lay eggs and also suckle its youngsters.
The duck-billed platypus is from Australia, which had become isolated from
the other continents millions of years ago after the super-continent
Pangaea broke up. Because of this, Australia preserved many animals
which no longer exist anywhere else in the world, including the duck-billed
platypus and the marsupials such as kangaroos and opossums. The
platypus is now protected now by law in Australia.
For pictures of a duck-billed platypus, type ‘duck-billed platypus’ into the
Images area of a search engine.
To do and to answer
1 Read the information above in your groups. Write down any questions
you want to ask, and be ready to share this with the class. This can be
about information you don’t understand, or something you want to find out
more about.
2 Read the information again, this time selecting the key scientific
information (by underlining or highlighting) that will help you decide which
vertebrate group the duck billed platypus belongs to.
3 Create a table with headings:
characteristics of mammals • characteristics of reptiles • characteristics of birds
Copy the information you have highlighted into the correct column.
Case study by Helen O’Connor from Preston Manor High School, Wembley
© in this format University of York and Nuffield Foundation 2008 • downloaded from www.21stcenturyscience.org
4 Decide, with reasons, which vertebrate group the duck-billed platypus
belongs to.
Duck-billed platypus: Extension activity
To study
Scientists publish new findings on the duck-billed platypus
An organism’s characteristics are determined by genes. Our skin, eye and
hair colour, height, weight, sex and blood group are examples of
characteristics which are determined by genes. We human beings have
about 30,000 genes, but simpler organisms have a lot fewer genes. The
more genes that humans have in common, the more similar they are. It
follows that the more genes two different animals have in common, the
more similar they are. In the last 30 years, scientists have developed a
method for finding out exactly what each gene is made of. They call this
method ‘gene sequencing’. Because most animals have many thousands
of genes, this is not an easy or quick process and often involves teams of
scientists working together all over the globe.
Quite recently over a hundred scientists working in America, England and
Australia managed to work out the gene sequence of the duck-billed
platypus. They told the rest of the scientific community about their findings
by publishing their results in a Journal called Nature.
To work out what the genes a platypus had, the scientists needed to take a
small tissue sample from a duck-billed platypus. This came from a female,
nicknamed Glennie, which had been captured in the wild in New South
Wales, Australia. They compared her genes with small sections from about
100 platypuses living in the wild. They found out that a duck-billed platypus
has about 18,500 genes.
The duck-billed platypus is classified as a mammal despite the fact that it
lays reptile like eggs, and has the bill of a duck and webbed feet. Scientists
found that the most of the genes in the platypus were shared with other
mammals, but some genes were more like reptile genes and others were
like bird genes.
To do and to answer
1 Read the information through carefully in your groups. Write down any
questions you want to ask, and be ready to share these. The questions can
be about information you don’t understand, or something you want to find
out more about.
2 Why do you think it was important to have many scientists working to
find the gene sequence of the duck billed platypus?
Case study by Helen O’Connor from Preston Manor High School, Wembley
© in this format University of York and Nuffield Foundation 2008 • downloaded from www.21stcenturyscience.org
3 Why is it important that scientists share their findings with other
scientists when they discover something new?
4 Do you think this new discovery of the duck-billed platypus genes means
that early scientists were right or wrong to classify it as a mammal?
Case study by Helen O’Connor from Preston Manor High School, Wembley
© in this format University of York and Nuffield Foundation 2008 • downloaded from www.21stcenturyscience.org