A STUDYGUIDE bY Andrew Fildes
11
www.metromagazine.com.au
www.theeducationshop.com.au
Overview
Planet Earth is a BBC production with five episodes in the first series (episodes one through
five) and six episodes in the second series (episodes six through eleven). Each episode
examines a specific environment, focussing on key species or relationships in each habitat;
the challenges they face; the behaviours they exhibit and the adaptations that enable them to
survive. Recent advances in photography are used to achieve some spectacular ‘first sights’
– in particular, stabilised aerial photography gives us remarkable views of migrating animals
and the techniques used by their predators to hunt them.
As the series examines pristine environments where possible, they are often extreme.
These are the parts of the world where few humans have chosen to live as the climate and
landscape is too challenging, too difficult and dangerous. The plants and animals that do
survive here have made some spectacular adaptations in forms and behaviour to live in these
far reaches of the planet.
The series is suitable for middle secondary students studying Science and SOSE, and for
senior secondary students of Biology, Environmental Science and Geography.
SCREEN EDUCATION
1
Episode Eleven: Ocean
Deep
The deep oceans, the pelagic zone covers more than half our planet’s surface
and is one of the least explored areas.
Much of it is simply an empty blackness
but the upper reaches are a vital part of
the earth’s habitat and climatic systems
and even the deepest, darkest zones
hold some remarkable surprises.
We begin with the largest fish of all, the
harmless whale shark that was almost
unknown a few years ago but has now
become a tourist spectacle in many
places. It cruises the warm waters of
the sub-tropical reefs, swallowing huge
quantities of plankton and small fish, as
does the manta ray, master of underwater flight. These are the great grazers of
the ocean, scooping up the microscopic plants and some small animals too.
True predators like the white tip shark
are long distance hunters, cruising the
vast reaches of the open ocean in the
constant hunt for scarce food while
large tribes of dolphins take a more
proactive approach, herding their prey
into tight bunches before they strike
mercilessly.
There are odd communities down
here, discovered only in the last few
years. Communities of strange worms
Episode 11: Ocean Deep
Time Log
Intro
00:00 - 01:25
Whale Shark
01:25 - 05:00
White Tip Shark
05:00 - 07:20
Dolphin and Shearwater
07:20 - 11:10
Plankton Night Grazers
11:10 - 13:53
Submarine Descent
13;53 - 17:30
Vampire Squid
17:30 - 18:57
Deep Ocean Floor
18:57 - 23:55
Atlantic Smokers
23:55 - 25:26
Dragon Chimneys
25:26 - 27:03
Death of a Vent
27:03 - 28:56
Sea Mounts
28:56 - 31:10
Nautilus
31:10 - 33:24
Dolphin and Squid
33:24 - 36:00
Sunfish
36:00 - 37:00
Frigate Birds on Ascension
37:00 - 41:56
Green Turtle Hatching
38:50 - 41:32
Sailfish
41:56 - 44:50
Blue Whale
44:50 - 48:09
(Timings are approximate)
gered more by the threats to its food
source than hunting, as in the past.
Resources
http://www.pbs.org/saf/1207/
features/113.htm (Black Smoker
Discovery)
3D IMAX movie – Aliens of the Deep
Species List
Whale Shark – Rhinocodon typus
Yellowfin Tuna – Thunnus albacares
Oceanic White Tip Shark – Carcharhinus longimanus
Pilot Fish – Naucrates ductor
Rainbow Runners – Elagatis bipinnulata
Dolphin – Tursiops spp., Delphinus
spp.
Blue Jack Mackerel – Trachurus picturatus
Cory’s Shearwater – Calonectris diomedea borealis
Mobula Ray – Mobula spp.
Indo-Pacific Sailfish – istiophorus
platypterus
Manta Ray – Manta birostris
Pteropod (Sea Butterfly) – Thecosomata
Sea Cucumber – Holothuroidea
Sea Spider – Muneurycope spp.
Sawtooth Eel – Serrivomer spp.
Dumbo Octopus – Grimpoteuthis spp.
Vampire Squid – Vampyroteuthis
infernalis
Sea Urchin – Phormosoma placenta
Monkfish – Lophius piscatorious
Giant Isopod – Bathynomus giganteus
Sperm Whale – Physeter macrocephalus
Spider Crabs – Hyas spp.
Squat Lobster – Shinkaia crosnieri
Giant Tubeworm – Riftia pachyptila
Whip Corals – Iridgorgia spp.
Chambered Nautilus – Nautilus pompilius
Pacific Spotted dolphin – Stenella
attenuata
Ocean Sunfish – Mola mola
Ascension Frigate Bird – Fregata
aquila
Green Turtle – Chelonia mydas
Atlantic Sailfish – Istiophorus albicans
Blue Whale – Balaenoptera musculus
SCREEN EDUCATION
But beneath the warm and sunlit waters
of the surface lie unimaginable depths
of dark, cold water. Some animals may
dive down there hunting food but most
of it is a high pressure desert, inhabited
by strange beasts that live on whatever falls, dead, from the upper levels.
These are highly specialized creatures,
adapted to filter their food blindly from
the downward drifting ‘snow’ or to hunt
each other in the total dark above the
great plains of sand and ooze. Like
the vampire squid which can light up
to confuse its predators or prey and
the scavengers of the plains sifting out
any organic particles from the ocean
floor. Eventually even the giants die and
the carcass of a huge sperm whale is
slowly consumed by the scavengers of
the abyss.
and crustaceans that huddle around
volcanic fissures on the ocean floor,
outpourings of superheated water in so
called ‘black smokers’. The plumes of
mineral rich hot water form huge chimneys and whole, unique ecosystems
tread a fine line between that water
venting at hundreds of degrees and the
freezing deeps around them. These are
contrasted with the great seamounts,
undersea volcanoes that rise kilometres
from the abyss to provide a platform for
life. Some like Ascension Island in the
Atlantic break the surface and create
a special habitat for frigate birds and
turtles. Finally we return to the ocean giants, creatures that could only live here
with the limitless space and the support
of the water. But this time it is the great
blue whale, the largest animal ever to
have lived on earth and now endan-
1
Blackline Master | Planet Earth | Episode 11: Ocean Deep
Viewing Questions
SCREEN EDUCATION
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9 What is the unique defence of the vampire squid?
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5 How deep can the shearwaters dive?
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SCREEN EDUCATION
1 How much of the planet is covered by deep ocean?
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15 What kind of coral can live in deep water?
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11 What do most sea floor animals eat?
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16 What do the dolphin prefer to eat?
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17 What does the sunfish (mola mola) eat in the deeps?
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SCREEN EDUCATION
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2
Blackline Master | Planet Earth | Episode 11: Ocean Deep
Ocean Deep Ecosystems
SCREEN EDUCATION
2
a
The open ocean zone beyond the
continental shelf is called the pelagic
zone. It is then divided into sub-zones
based on depth. The first thing to
consider is whether light can penetrate
– if any light from the surface at all
can be detected, it is called the photic
zone. Below that it is totally dark and
referred to as aphotic.
several centimetres in diameter in the
weeks before they sink to the abyssal
plains.
This snow is the producer of the deep
sea ecosystem where no light penetrates and what is not eaten during its
descent, becomes part of the layer of
organic waste on the sea floor which
is scavenged and filtered by small
animals. Without it, nothing could live
permanently in the deep waters.
The pelagic area is further divided
into depth zones, each with its own
ecosystem. This is often a function of
depth, temperature and pressure at
the increasing depths, as well as what
light can penetrate.
Epipelagic (Surface down to 200m).
Epi – surface. This is the surface zone
where enough light penetrates to allow photosynthesis. Most plants and
animals live in this thin zone and the
large fish that cruise long distances,
like sharks and sailfish are usually
found here.
Mesopelagic (200m to 1,000m
deep).
Meso – middle. This is the zone where
the light gets increasingly dim and
plant growth – photosynthesis is impossible. Phytoplankton – microscopic
plants cannot grow so the ecosystem
has to live on other materials such as
detritus – sinking debris and rubbish.
Abyssopelagic (4,000m to ocean
floor).
Abyssos – bottomless. No light
whatsoever and huge pressure. Most
animals are blind and colourless,
The bottom three zones are very
similar and are almost lifeless except
around any source of energy like a
hydrothermal vent – black smoker.
1. The largest predators on earth live
on the some of the smallest organisms. How does this work?
2. Whale sharks have become an
important ecotourism resource.
Why?
3. The dolphins and shearwaters
seem to work together to catch
small fish. Are they competing or
co-operating?
4. Deep water animals often seem to
have bizarre and outrageously ugly
shapes and adaptations. How can
we explain this?
5. Photoluminescence is a strange
adaptation and is used by terrestrial and marine animals. How does
it work?
Marine Snow
Extension Tasks
Deep sea organisms rely mostly on
so-called ‘marine snow’ which falls
constantly from the upper levels. It
is mostly organic ‘detritus’ (waste)
and those animals that rely on it are
referred to as detritivores – waste
feeders. It may include dead or dying microscopic animals and plants
(plankton), protists (diatoms), fecal matter and inorganic particles
(sand and dust). The ‘snowflakes’
are clumps or strings of material held
together by strings of sugary mucus,
the wastes of bacteria that are feeding
on the contents of the wastes. Those
bacteria become an important part
of the food resource in the material.
They continue to grow and may reach
•
wandering across the abyssal plains
filtering out small organic particles or
scavenging dead animals that sink to
the floor.
Hadopelagic (Deep ocean trenches in the sea floor).
Hades – hell, the ancient Greek underworld. Mostly unexplored and with
little life.
•
•
Draw up a visual presentation
(poster) that compares the ecosystems of the pelagic zones – compare the photic and aphotic zones.
Prepare a visual presentation or
report on the unique ecosystem
of the hydrothermal vents of the
deeps (black smokers), explaining
how these systems can survive
without any photosynthesis to
produce energy.
Research and report on the exploration of the abyssal depths – what
research equipment and techniques have been used and what
has been discovered in recent
years?
SCREEN EDUCATION
Bathypelagic (1,000 to 4,000m
deep).
Bathys – deep. Totally dark apart
from those animals that can produce
their own light, using photoluminescent bacteria – they have symbiotic
bacteria in their tissues that can glow
and can be used as lures or decoys,
rather than headlights! As there are no
plants, small animals live on the falling
marine ‘snow’ and larger animals are
predators. Giant squid live here and
sperm whales dive to catch them.
Pelagic Ecosystems
– Discussion Questions
3
Case Study | Planet Earth | Episode 11: Ocean Deep
‘Black Smokers’
SCREEN EDUCATION
3
a
Not Photosynthesis
– Chemosynthesis!
We are used to thinking of ecosystems
as being based on producer organisms
– green plants that can convert inorganic materials into organic energy through
photosynthesis. Even systems that exist
in total darkness still rely on it – cave
systems live on material brought in from
the outside, such as bat droppings
(guano) and even the creatures of the
black abyssal plains kilometres down
beneath the ocean rely on the ‘snow’,
the constant rain of decaying material
that slowly settles down through the
water and feeds the detritivores, the
rubbish feeders.
However, there is one class of systems
that seems to defy this absolute rule
– the so-called ‘smokers’ or volcanic
vents on the ocean floors. These have
only been explored in the last twenty
to thirty years, since their discovery in
1977 and represent the most extreme environments on earth in terms
of temperature, pressure and toxic
chemistry. We may be surprised to find
blue-green algae surviving in the near
boiling waters of hot springs up here
in the sunshine but they are delicate in
comparison to the organisms that cling
to life in these odd zones.
Usually microscopic organisms,
archaea, convert heat and sulphides
directly into organic material by
an alternative process called
chemosynthesis – then the higher
organisms such as worms and clams
can feed on those, so creating the
two base layers of the food chain.
Like bacteria, archaea are singlecelled organisms lacking nuclei
and so are prokaryotes, classified
as monera. They were originally
described in extreme environments,
but have since been found in all types
of habitats. Many are referred to as
‘extremophiles’ – organisms that love
extreme environments.
Archaea are usually placed into
three groups based on preferred
habitat. These are the halophiles,
methanogens, and thermophiles.
Halophiles live in extremely saline
environments. Methanogens live
in anaerobic environments and
produce methane. Many archaeans
are thermophiles. They can survive
and thrive at even relatively high
temperatures, often above 100°C, as
found in geysers and black smokers.
Other extremophiles are found in
very cold habitats or in highly acidic,
or alkaline water. However, other
archaeans are mesophiles, and have
been found in environments like
marshland, sewage, sea water and
soil. Many methanogenic archaea are
found in the digestive tracts of animals
such as ruminants, termites, and
humans. Archaea are usually harmless
to other organisms and none are
known to cause disease.
Chemosynthesis is the biological
conversion of carbon molecules
(usually carbon dioxide or methane)
and nutrients into organic matter
using the oxidation of inorganic
molecules (e.g. hydrogen gas,
hydrogen sulfide) or methane as
a source of energy, rather than
sunlight, as in photosynthesis.
Large populations of animals can
be supported by chemosynthetic
primary production at hydrothermal
vents. Chemoautotrophs, organisms
that obtain carbon through
chemosynthesis, are responsible for
the primary production in oxygendeficient environments and generally
fall into four groups: methanogens,
halophiles, sulphur reducers, and
thermoacidophiles.
Many microorganisms in dark regions
of the oceans use chemosynthesis
to produce biomass from 1-carbon
molecules. There are two categories.
In the rare sites at which hydrogen
molecules (H2) are available such as
smokers, the energy available from the
reaction between CO2 and H2 (leading
to production of methane, CH4) can be
large enough to drive the production
of biomass.
Alternatively, in most oceanic
environments beyond the
volcanic environments, energy
for chemosynthesis derives from
reactions between O2 and substances
such as hydrogen sulfide or
ammonia. In this second case, the
chemosynthetic microorganisms are
dependent on photosynthesis which
occurs elsewhere and which produces
the O2 that they require.
Because it makes life possible in
such extreme environments and
habitats, it has been suggested that
chemosynthesis may support life
below the surface of Mars, on Jupiter’s
moon Europa, and on other planets.
Hydrogen sulphide chemosynthesis –
CO2+O2+4{H2S}‡CH2O+4{S}+3{H2O}
SCREEN EDUCATION
They are hydrothermal vents, where
superheated water bubbles up through
the earth’s crust at its thinnest points
– volcanically active ocean floor zones.
Because they are at an average depth
of over 2,000 metres deep, the water
does not boil even though it can be at
400 degrees due to pressure. The vent
water is a soup of dissolved minerals,
often rich in sulphides which crystallise
as they hit the cold ocean water, forming chimney structures, sometimes at
up to 300mm per day . Smokers occur
in groups but each one tends to have a
unique ecosystem because, although
some species can migrate from one
to another, many cannot and can only
survive in a narrow temperature zone
around each vent.
If sunlight is unavailable and
photosynthesis impossible, how
can the organisms make use of
the heat energy from the vent to
establish a habitat? There is one
case of a bacterium that can use
the faint glow from the volcanic
activity for photosynthesis, the only
organism known to use any other
light but sunlight, but this is a unique
exception.
10
3
ANSWER SHEET
Viewing Questions
Discussion Questions
1 Over half of the planet is deep
ocean
2 The whale shark
3 The top 100m of open water
4 SONAR (SOund Navigation And
Ranging) – sound echo location
5 Twenty metres
6 The plankton rises every night
7 Sailfish and manta ray
8 The rubbish (detritus) sinking from
the surface animals
9 Lights from bioluminescent bacteria in its arms to confuse predators
10 300 atmospheres (300x surface
pressure)
11 They scavenge dead animals or
filter particles
12 Hot volcanic vents
13 Giant tubeworms
14 Up to thirty thousand
15 Soft corals
16 Squid
17 Jellyfish
18 The blue whale
19 Krill
20 300,000. Now three per cent of
that – 9,000
1 The big whales, manta rays and
the whale shark live on plankton
and krill. This food resource is
huge and only very large animals
with special adaptations to their
mouths can scoop up the huge
quantities that are needed to support their massive bodies. It is only
possible if there are large algal
‘blooms’ and huge swarms of krill
– anything that threatens those
swarms will threaten the large
marine animals.
2 They migrate on a regular pattern
and are easy to approach – they
are very docile, quite harmless. It
is possible to swim with them in
areas like the Ningaloo Reef off
north-western Australia and a local
industry has grown up around their
migration.
3 Neither really. The shearwaters
are taking the opportunity as the
fish are driven to the surface and
the dolphin are advantaged as the
fish are confused and driven back
down by the birds. It is an acciden-
tal co-operation if anything.
4 It is totally dark so they don’t
need to be pretty or worry about
camouflage or speed. Some of
the adaptations that allow them to
survive look very strange but they
are working blind – huge mouths
with massive hooked teeth may
help them latch on to prey with just
a touch!.
5 Organisms like glow worms,
fireflies, and deep sea creatures
are in a symbiotic relationship with
photoluminescent bacteria. These
bacteria have the ability to emit
light energy and live in the tissues
of other animals when there is an
advantage for both species. The
bacterium is fed and protected
with the tissues while the host may
use them as a sexual lure (fireflies),
predatory lure (angler fish) or a
defence (vampire squid).
BBC and Planet Earth are trade marks
of the British Broadcasting Corporation and are used under licence.
Planet Earth logo © BBC 2006. BBC
logo © BBC 1996.
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