Previously
From page 20 There are millions of species of living things but we
don’t really know how many.
From page 28 Variation comes about due to genetic and
environmental reasons.
Unit 5
Remarkable nature
How amazing is nature?
This Unit is our ‘Guinness Book of Records’ for nature.
We will learn about a small selection of some of the most
remarkable animals and plants on Earth.
In this Unit, you will learn:
that blue whales and giant redwood trees are the
qq
biggest living things on Earth;
how whales live, feed and communicate;
qq
why bees are important to us and the Earth;
qq
how honeybees communicate information about food
qq
to each other;
why some animals are threatened by human activity;
qq
that parrots are amongst the most intelligent of all
qq
birds and can solve problems;
that a bristle cone pine tree is one of the oldest things
qq
on the planet;
that Welwitschia is weird!
qq
Key words
baleen
biomass
communicate
conservation status
extinct
girth
32 SMART SCIENCE
imitate
intelligence
krill
waggle dance
Welwitschia
Remarkable nature
What is special about whales?
There are 86 species of whales, including dolphins
and porpoises. Many of them are very rare and
one, the Baiji or Chinese River Dolphin, was
declared extinct (none left alive) in 2005. Here,
we will learn about the very large ocean-living
whales. We will look in particular at the blue
whale, Balaenoptera musculus, which at about
30 metres long and weighing in at 200 000 kg is the
biggest known animal to ever have existed.
What does a blue whale eat?
Possibly the most remarkable thing
about this gigantic animal is that its
food is tiny! It feeds almost entirely
on krill, a small crustacean that exists
in vast numbers. Let’s work out just
how much krill food whales could find.
Name
Genus and
species
Mass
Length
Food
Special
skills
Blue whale
Balaenoptera
musculus
200 000 kg
Record
30 m
Krill, tiny crustaceans
Communicates
by ‘song’ across
hundreds of miles
Biggest animal we
know of, ever
If we add the mass of all the humans
on the planet together, we call the total
the biomass of the human species. In
2012, there were about 7 000 000 000
humans on Earth. On average, a human
has a mass of about 50 kg.
So the biomass of humans = 7 000 000 000 × 50 kg = 350 billion kg
One Antarctic krill has a mass of about 0.5 g, so a human has a mass 100 000 times
bigger than a krill! We think there are about 800 trillion krill living in the Southern
Ocean. So what is the biomass of krill?
Biomass of krill = 800 000 000 000 000 × 0.5 g = 400 billion kg
So the tiny Antarctic krill living in the Southern Ocean has a total biomass more than
that of all humans on the planet! That’s a lot of food for whales.
However, a blue whale eats around 40 million krill every day. The whale moves forward
into a group of krill, and takes them into its massive mouth, together with hundreds of
gallons of seawater. The water is squeezed through hard baleen plates that hang from
the roof of its mouth. Krill cannot pass through the baleen plates and are swallowed.
How much mass of krill does a blue whale eat every day?
BIOLOGY 33
Unit 5
How do whales communicate?
Another remarkable feature of some whales is their ability to communicate with each
other in complex ways. Unfortunately, one thing that cannot be done in a book is to
convey sounds.
The most complex song is that of the male humpback whale. Each song can last for up
to 20 minutes, and the males will sing all day. We have not yet worked out why they
sing these songs or what they mean. They may be challenges to other males. At certain
times of the year, the song changes and is used to herd the fish that these whales eat.
Search online for recordings of whale songs. Try using your
descriptive writing ability to convey the songs in words to
others. Let them read what you have written, listen to the
song and ask them what they think of your description.
Why are whales under threat?
There is much else to learn
about whales, but perhaps
the most important fact to
end with is that humans
threaten many of them. So
that we can understand which
animals are most in danger,
the International Union for
the Conservation of Nature
(IUCN) was formed in 1948.
The IUCN is working to give
all species of living things a
‘conservation status’.
Because of hunting and other
human activities, many species
of whale are threatened.
Extinct (EX)
Extinct in the Wild (EX)
Threatened categories
Critically Endangered (CR)
Extinction
risk
Endangered (EN)
Vulnerable (VU)
Near Threatened (NT)
Least Concern (LC)
–
The categories the IUCN uses to describe how much
at risk a species can be.
Species
World population Conservation status
Blue whale
under 25 000
EN Endangered
Fin whale
under 100 000
EN Endangered
North Atlantic right whale
under 300
EN Endangered
Sperm whale
under 2 million
VU Vulnerable
Common minke whale
not known
NT Near Threatened
34 SMART SCIENCE
+
Remarkable nature
What is special about bees?
Bees are a huge group of insects (about
20 000 species) closely related to ants and
wasps. Here we are going to look at the
Western honeybee, Apis mellifera, and in
particular its ability to communicate.
How do honeybees live?
Honeybees live in colonies of up to 80 000
individuals. They feed on nectar and pollen
collected from local flowers. When a foraging worker
finds a new patch of flowers it can communicate
information about it to others. The returning bee
performs a ‘round dance’, telling others that food
is within 50 m. It then does a ‘waggle dance’,
which provides more detailed information about the
distance and direction of the food.
Sun
Western Honeybee
Name
Genus and Apis mellifera
species
0.25 g (a colony of
Mass
50 000 bees would
weigh about 12 kg)
Just over 1 cm
Length
Nectar and pollen
Food
Lives in big colonies
Special
Communicates by
skills
‘dances’
Helps flowering plants
Record
and many crops
reproduce through
pollination
flower
The angle a of its dance to the vertical shows
qq
2
a
1 s = 1 km
start
1
the direction of the flower relative to the Sun.
The length of time it takes to dance the
qq
wiggly line, in seconds, measures the distance
to the flower in kilometres.
It returns to the start from the right, repeats
qq
the waggle, then returns from the left, and
so on.
Bees are not the only animals that use unusual methods of communicating
with each other.
Find out more about bee dances and, in a table, compare
this method of communication with that of three other
animals and humans. Can you find out any information about
communication in plants?
BIOLOGY 35
Unit 5
Why are bees under threat?
Honeybees are very important to us and the environment.
They provide us with honey when we keep them in beehives.
qq
They make sure most flowering plants and crops reproduce, because they pollinate
qq
the flowers.
Unfortunately, a combination of natural and human causes means bee numbers have
reduced dramatically.
Over the last hundred years the number of beehives in the UK has declined from over
qq
1 million to only 280 000.
There are several diseases that threaten bees – in 2008, 30% of all bees in the UK
qq
were lost to such diseases.
Human activity means that large areas where bees live and forage have disappeared.
qq
These areas include traditional meadows and heather moors.
Explain why bees are important to the environment around us.
What do you think can be done to help bees?
What is special about parrots?
It is well known that parrots can imitate human
speech, but being able to imitate is not the same
as having intelligence. Better evidence comes
from experiments showing that parrots can solve
puzzles. In addition, some parrots have been
shown to use language in a creative way. One,
an African grey parrot called N’kisi, is said to
have a vocabulary of 950 words. Once, when the
chimpanzee expert Jane Goodall visited N’kisi,
the bird said ‘got a chimp’ because it had seen
a photograph of her with chimpanzees.
1Find out how many words a
human child will learn by
the age of three. What does
that suggest about N’kisi’s
intelligence?
2 Keep a vocabulary log by noting
every new word you learn in a
week. You may be surprised!
36 SMART SCIENCE
Name
African Grey Parrot
Genus and Psittacus erith
acus
species
Mass
0.5 kg
Length
0.3 m
Food
Fruit and nuts
Special
Can imitate human
skills
speech
Able to solve
problems
Record
Largest number of
human words learnt
by an animal – 950
Remarkable nature
What is special about ‘General Sherman’
and the bristle cone pine?
If the blue whale is the biggest animal ever to
have lived, the giant redwood is probably the
biggest plant. For example, the tree called ‘General
Sherman’ is the biggest alive today. It is 83.8 m
(275 feet) high and has a girth (distance around
it) of over 30 m (100 feet). It is thought to weigh
over 2 000 000 kg. It accumulates new wood at
a rate equivalent to the wood in a 30-year-old
oak tree every year. The General Sherman grows,
along with other giant redwood trees, in the Sierra
Nevada Mountains of California.
Name
Genus and
species
Mass
Length
Food
Special
skills
Name
Bristle Cone Pine
Genus and Pinus longaeva
species
Mass
20 000 kg
Length
About 15 m
Food
Sunlight, water, carbon
dioxide and minerals
Special
Nearly 5000 years old
skills
Record
Oldest living tree on
Earth
Record
Giant Redwood
Sequoia gigantea
2 000 000 kg
83.8 m
Sunlight, water,
carbon dioxide and
minerals
Grows enough wood
every year to make
a whole 30-year-old
oak tree
Biggest plant we
know of
Not very far away in the White
Mountains of California grows a bristle
cone pine tree called Methuselah, which
is nearly 5000 years old!
The ‘General Sherman’ is not in fact the largest living thing on Earth, nor is
‘Methuselah’ the oldest. ‘General Sherman’ is the largest single-stemmed tree
and ‘Methuselah’ is thought to be the oldest non-clonal living thing.
Using the clues above, see if you can find out which are truly
the largest and oldest living things. Write a paragraph about
each of them.
BIOLOGY 37
Unit 5
Why is Welwitschia truly special?
Welwitschia has been given a number of different
descriptions; the world’s ugliest, weirdest, strangest,
most wonderful and most bizarre plant.
Welwitschia is the only species in its genus, the
only genus in its family and the only family in its
order. There is no other species of living thing even
remotely like it!
It lives on the coast of Namibia and Angola in South
West Africa. This region is a dry desert but water
is available in early morning mists. Welwitschia
consists of a long taproot, a short trunk and just
two leaves. The leaves grow throughout the life of
the plant, which can be as long as 2000 years. The
leaves curve downwards, so that they collect the
mist into water droplets. These droplets run into the
soil and to the roots.
Growing plants have leaves about 2 m long, but the
wind blowing them against the sand wears away the
growth. If they weren’t constantly worn away like this
it is thought each leaf would be well over 100 m long!
Name
Genus and
species
Mass
Length
Food
Special
skills
Record
Welwitschia
Welwitschia mirabilis
100 kg
About 2 m
Sunlight, water,
carbon dioxide and
minerals
Lives in very harsh
conditions
Very, very unique
You need to remember that:
The world is full of amazing living things. qq
Whales and bees are threatened by
qq
human activity.
Blue whales are the biggest animals that
qq
have ever lived.
Parrots are amongst the most intelligent
qq
of all birds and can solve problems.
Whales feed off some of the smallest
qq
animals on the Earth.
The biggest giant redwood trees are some
qq
of the largest living things on the planet.
Whales communicate with each other by
qq
‘singing’ under water.
Bristle cone pine trees can live to be
qq
some of the oldest things on the planet.
Honey bees communicate information
qq
about food to each other through
Welwitschia is weird!
qq
‘waggle dances’.
Next time
Unit 15 Each living thing is adapted to the place it lives, its habitat (page 95).
Unit 16 There are over 7 billion people on Earth, which puts a big strain on the environment (page 104).
38 SMART SCIENCE