What organisms are typical of major deep-sea
habitats, and how do they interact?
Keywords to look up before the lesson
Cold seeps
Methane hydrate ice
Chemosynthesis
Brine pool
Trophic level
Pelagic zone
Epipelagic zone
Mesopelagic zone
Bathypelagic zone
Hadopelagic zone
Benthic zone
Intertidal zone
Subtidal zone
Bathyal zone
Abyssal zone
Hadal zone
Hydrothermal vent
https://oceanexplorer.noaa.gov/edu/lessonplans/zone.pdf
Background Information
Cold seeps are areas of the ocean floor where
gases (such as methane and hydrogen sulfide)
and oil seep out of sediments. These areas are
commonly found along continental margins, and
are home to many species of organisms that
have not been found anywhere else on Earth.
Recently, increasing attention has been focused
on cold seeps in the Gulf of Mexico, an area that
produces more petroleum than any other region
in the United States. Responsibility for managing
exploration and development of mineral resources
on the Nation’s outer continental shelf is a central
the mission of the U.S. Department of the Interior’s
Minerals Management Service (MMS). In addition to managing the revenues from mineral
resources, an integral part of this mission is to
protect unique and sensitive environments where
these resources are found. MMS scientists are
particularly interested in finding deep-sea chemosynthetic communities in the Gulf of Mexico,
because these are unique communities that often
include species that are new to science and
whose potential importance is presently unknown.
In addition, the presence of these communities
often indicates the presence of hydrocarbons at
the surface of the seafloor.
The 2006 Expedition to the Deep Slope was
focussed on discovering and studying the sea
floor communities found near seeping hydrocarbons on hard bottom in the deep Gulf of Mexico.
The sites visited by the Expedition were in areas
where energy companies will soon begin to drill
for oil and gas. A key objective was to provide
information on the ecology and biodiversity of
these communities to regulatory agencies and
energy companies. Dives by scientists aboard
the research submersible ALVIN revealed that
hydrocarbons seepage and chemosynthetic communities were present at all ten sites visited by the
Expedition. The most abundant chemosynthetic
organisms seen were mussels and vestimentiferan
tubeworms. Expedition to the Deep Slope 2007
is focused on detailed sampling and mapping of
four key sites visited in 2006, as well as exploring new sites identified from seismic survey data.
Cold-seep communities are surrounded by a much
larger ocean environment. Very little is known
about interactions between cold-seep communities and organisms in other ocean habitats. This activity focuses on major ocean habitats, organisms
typically found in these habitats, and the interactions that take place within and between these
habitats.
Ocean habitats are usually categorized into
zones:
I. Pelagic zones are found in the water column
above the bottom. Organisms that inhabit
pelagic zones are divided into plankton that
drift with the ocean currents and nekton that
can swim and control their motion in the
water (at least to some extent).
A. The Epipelagic zone includes surface
waters where light is adequate for photosynthesis (about 200m, maximum).
Phytoplankton are the dominant primary
producers in this zone.
B. The Mesopelagic zone (about 200m1000m) is the twilight zone. Because
there is not enough light for photosynthesis, much less energy is available to
support animal life. Bacteria and detritus
(pieces of dead plants and animals that
slowly settle to the bottom) are the primary sources of food for animals like
jellyfishes that are confined to this zone.
Other animals, including squids, fishes,
and shrimps can move up and down
through the water column, and have a
a wider range of food available to them.
C. The Bathypelagic zone (sometimes
divided further into an additional
Abyssopelagic Zone) has no light at
all, with the exception of light produced
by bioluminescent organisms. Deep-sea
organisms are dependent upon production in other zones. The base of bathypelagic food chains may be primary production in shallower water (obtained by
feeding on detritus or on other animals
feeding in shallower water) or chemosynthetic communities
like hydrothermal vents or cold-seeps.
D. The Hadopelagic zone is sometimes used
to include the water column in the deepest
ocean trenches (about 11,000 m).
II. Benthic zones are areas on or in the ocean
bottom. Animals that swim near the bottom
and called “benthopelagic.”
A. The Intertidal zone is on the shore
between the level of high and low tide.
B. The Subtidal zone includes the ocean bottom on continental shelves down to about
300 m. Green plants are the base of
food chains in shallower waters, but bacteria and detritus are the primary energy
source below about 200 m.
C. The Bathyal zone includes the rest of the
continental shelf (between about 300 m
and 3,000 m).
D. The Abyssal zone is the ocean bottom
between 3,000 m and 6,000 m. The bottom is primarily muddy and flat in most
places (hence the common term “abyssal
plain”). This is the largest benthic zone
and covers about half of the Earth’s surface.
E. The Hadal zone is sometimes used to
describe the very deep ocean bottom
between 6,000 m and 11,000 m
F. Vents and seeps are unusual deep-water
habitats that support communities of living organisms whose food chains are
based on chemosynthetic bacteria, rather
than photosynthetic activity near the surface. Vent and seep communities may,
in turn, be significant energy (food)
source for organisms living in other benthic habitats nearby
Learning Procedure
1. To prepare for this lesson, visit http://oceanexplorer.
noaa.gov/explorations/07mexico/welcome.html for information about Expedition to the Deep Slope 2007.
You may want to visit http://www.bio.psu.edu/cold_seeps
for a virtual tour of a cold seep community, and
http://www.bio.psu.edu/hotvents for a virtual tour of a
hydrothermal vent community.
2. Lead a discussion of the major categories of
ocean habitat. Introduce the recently-discovered
deep-sea chemosynthetic communities (hydrothermal vents and cold seeps). Emphasize the
contrast between communities that depend
upon chemosynthesis with those dependent
upon photosynthesis. You may want to point
out that through both processes, organisms
build sugars from carbon dioxide and water.
This process requires energy; photosynthesizers
obtain this energy from the sun, while chemosynthesizers obtain energy from chemical reactions. Review the concepts of food chains and
food webs, including the concept of trophic
levels (primary producer, primary consumer,
secondary consumer, and tertiary consumer).
Be sure students understand that food chains
in most of the habitats are largely based upon
photosynthetic production, either directly (primary consumers obtain energy from photosynthetic
plants) or indirectly (primary consumers obtain
energy from detritus). This situation is fundamentally different in deep-sea chemosynthetic communities, which may also provide an alternative
the basis for food chains in adjacent habitats.
3. Assign each student group one or more of the
following deep ocean habitats to research:
• Mesopelagic zone
• Bathypelagic zone
• Hadopelagic zone
• Bathyal zone
• Abyssal zone
• Hadal zone
• Hydrothermal vents
• Cold seeps
Each student group should identify six organisms typical of their assigned habitat, and
determine the energy (food) source(s) of each
of these organisms. It may not be possible to
precisely determine specific foods in all cases,
but students should be able to draw reasonable inferences from information about related
organisms and anatomical features that may
give clues about what the animals eat. Students
should prepare a 5 x 7 index card for each
an organism with an illustration of the organism
(photocopies from reference material, downloaded internet pictures, or their own sketches),
notes on where the organism is found, the approximate size of the organism, and its trophic level
(whether it is a primary producer, primary
consumer, secondary consumer, or tertiary consumer).
4. Have each student group orally present their
research results to the entire class. On a corkboard, flip chart, or piece of poster board
draw a general profile of ocean habitats (see
“Generalized Ocean Habitats” diagram), and
arrange the cards to show representative organisms in each habitat. When all cards have been
attached to the base material, draw lines to
indicate trophic (feeding) relationships between
these organisms.
5. Lead a discussion of the food web the students
have created. What is the source of primary
production in each habitat? What would the
students infer about the relative abundance
of each trophic level? In the simplest analysis,
organisms at lower trophic levels (primary producers and primary consumers) must be more
abundant than those on higher trophic levels. If
this does not appear to be true, then there must
be additional energy sources for the higher
trophic levels (for example, some secondary
or tertiary predators may feed in more than
one habitat. Considering that the abyssal plain
covers about half of the Earth’s surface, and
is largely unexplored, how might the students’
ocean food web change with further exploration?
The Bridge Connection
www.vims.edu/bridge/ – Click on “Biology” in the
the navigation menu to the left, then “Plankton,” then
“Phytoplankton” for resources on ocean food
webs. Click on “Ecology” then “Deep Sea” for
resources on deep-sea communities.
The “Me” Connection
Have students write a short essay describing their
personal position in a food web, and how they
could adapt if their source of primary production
were no longer available.
Connections to Other Subjects
English/Language Arts, Earth Science
Assessment
Results and presentation of the research component of this activity provide a basis for group
evaluation. In addition, individual written interpretations of the pooled results may be required
prior to Step 4 to provide a means of individual
assessment.
Extensions
Visit http://oceanexplorer.noaa.gov/explorations/07mexico/welcome.html
to keep up to date with the latest
Expedition to the Deep Slope 2007 discoveries,
and to find out what researchers are learning
about cold-seep communities.
habitats, and how do they interact?
Keywords to look up before the lesson
Cold seeps
Methane hydrate ice
Chemosynthesis
Brine pool
Trophic level
Pelagic zone
Epipelagic zone
Mesopelagic zone
Bathypelagic zone
Hadopelagic zone
Benthic zone
Intertidal zone
Subtidal zone
Bathyal zone
Abyssal zone
Hadal zone
Hydrothermal vent
https://oceanexplorer.noaa.gov/edu/lessonplans/zone.pdf
Background Information
Cold seeps are areas of the ocean floor where
gases (such as methane and hydrogen sulfide)
and oil seep out of sediments. These areas are
commonly found along continental margins, and
are home to many species of organisms that
have not been found anywhere else on Earth.
Recently, increasing attention has been focused
on cold seeps in the Gulf of Mexico, an area that
produces more petroleum than any other region
in the United States. Responsibility for managing
exploration and development of mineral resources
on the Nation’s outer continental shelf is a central
the mission of the U.S. Department of the Interior’s
Minerals Management Service (MMS). In addition to managing the revenues from mineral
resources, an integral part of this mission is to
protect unique and sensitive environments where
these resources are found. MMS scientists are
particularly interested in finding deep-sea chemosynthetic communities in the Gulf of Mexico,
because these are unique communities that often
include species that are new to science and
whose potential importance is presently unknown.
In addition, the presence of these communities
often indicates the presence of hydrocarbons at
the surface of the seafloor.
The 2006 Expedition to the Deep Slope was
focussed on discovering and studying the sea
floor communities found near seeping hydrocarbons on hard bottom in the deep Gulf of Mexico.
The sites visited by the Expedition were in areas
where energy companies will soon begin to drill
for oil and gas. A key objective was to provide
information on the ecology and biodiversity of
these communities to regulatory agencies and
energy companies. Dives by scientists aboard
the research submersible ALVIN revealed that
hydrocarbons seepage and chemosynthetic communities were present at all ten sites visited by the
Expedition. The most abundant chemosynthetic
organisms seen were mussels and vestimentiferan
tubeworms. Expedition to the Deep Slope 2007
is focused on detailed sampling and mapping of
four key sites visited in 2006, as well as exploring new sites identified from seismic survey data.
Cold-seep communities are surrounded by a much
larger ocean environment. Very little is known
about interactions between cold-seep communities and organisms in other ocean habitats. This activity focuses on major ocean habitats, organisms
typically found in these habitats, and the interactions that take place within and between these
habitats.
Ocean habitats are usually categorized into
zones:
I. Pelagic zones are found in the water column
above the bottom. Organisms that inhabit
pelagic zones are divided into plankton that
drift with the ocean currents and nekton that
can swim and control their motion in the
water (at least to some extent).
A. The Epipelagic zone includes surface
waters where light is adequate for photosynthesis (about 200m, maximum).
Phytoplankton are the dominant primary
producers in this zone.
B. The Mesopelagic zone (about 200m1000m) is the twilight zone. Because
there is not enough light for photosynthesis, much less energy is available to
support animal life. Bacteria and detritus
(pieces of dead plants and animals that
slowly settle to the bottom) are the primary sources of food for animals like
jellyfishes that are confined to this zone.
Other animals, including squids, fishes,
and shrimps can move up and down
through the water column, and have a
a wider range of food available to them.
C. The Bathypelagic zone (sometimes
divided further into an additional
Abyssopelagic Zone) has no light at
all, with the exception of light produced
by bioluminescent organisms. Deep-sea
organisms are dependent upon production in other zones. The base of bathypelagic food chains may be primary production in shallower water (obtained by
feeding on detritus or on other animals
feeding in shallower water) or chemosynthetic communities
like hydrothermal vents or cold-seeps.
D. The Hadopelagic zone is sometimes used
to include the water column in the deepest
ocean trenches (about 11,000 m).
II. Benthic zones are areas on or in the ocean
bottom. Animals that swim near the bottom
and called “benthopelagic.”
A. The Intertidal zone is on the shore
between the level of high and low tide.
B. The Subtidal zone includes the ocean bottom on continental shelves down to about
300 m. Green plants are the base of
food chains in shallower waters, but bacteria and detritus are the primary energy
source below about 200 m.
C. The Bathyal zone includes the rest of the
continental shelf (between about 300 m
and 3,000 m).
D. The Abyssal zone is the ocean bottom
between 3,000 m and 6,000 m. The bottom is primarily muddy and flat in most
places (hence the common term “abyssal
plain”). This is the largest benthic zone
and covers about half of the Earth’s surface.
E. The Hadal zone is sometimes used to
describe the very deep ocean bottom
between 6,000 m and 11,000 m
F. Vents and seeps are unusual deep-water
habitats that support communities of living organisms whose food chains are
based on chemosynthetic bacteria, rather
than photosynthetic activity near the surface. Vent and seep communities may,
in turn, be significant energy (food)
source for organisms living in other benthic habitats nearby
Learning Procedure
1. To prepare for this lesson, visit http://oceanexplorer.
noaa.gov/explorations/07mexico/welcome.html for information about Expedition to the Deep Slope 2007.
You may want to visit http://www.bio.psu.edu/cold_seeps
for a virtual tour of a cold seep community, and
http://www.bio.psu.edu/hotvents for a virtual tour of a
hydrothermal vent community.
2. Lead a discussion of the major categories of
ocean habitat. Introduce the recently-discovered
deep-sea chemosynthetic communities (hydrothermal vents and cold seeps). Emphasize the
contrast between communities that depend
upon chemosynthesis with those dependent
upon photosynthesis. You may want to point
out that through both processes, organisms
build sugars from carbon dioxide and water.
This process requires energy; photosynthesizers
obtain this energy from the sun, while chemosynthesizers obtain energy from chemical reactions. Review the concepts of food chains and
food webs, including the concept of trophic
levels (primary producer, primary consumer,
secondary consumer, and tertiary consumer).
Be sure students understand that food chains
in most of the habitats are largely based upon
photosynthetic production, either directly (primary consumers obtain energy from photosynthetic
plants) or indirectly (primary consumers obtain
energy from detritus). This situation is fundamentally different in deep-sea chemosynthetic communities, which may also provide an alternative
the basis for food chains in adjacent habitats.
3. Assign each student group one or more of the
following deep ocean habitats to research:
• Mesopelagic zone
• Bathypelagic zone
• Hadopelagic zone
• Bathyal zone
• Abyssal zone
• Hadal zone
• Hydrothermal vents
• Cold seeps
Each student group should identify six organisms typical of their assigned habitat, and
determine the energy (food) source(s) of each
of these organisms. It may not be possible to
precisely determine specific foods in all cases,
but students should be able to draw reasonable inferences from information about related
organisms and anatomical features that may
give clues about what the animals eat. Students
should prepare a 5 x 7 index card for each
an organism with an illustration of the organism
(photocopies from reference material, downloaded internet pictures, or their own sketches),
notes on where the organism is found, the approximate size of the organism, and its trophic level
(whether it is a primary producer, primary
consumer, secondary consumer, or tertiary consumer).
4. Have each student group orally present their
research results to the entire class. On a corkboard, flip chart, or piece of poster board
draw a general profile of ocean habitats (see
“Generalized Ocean Habitats” diagram), and
arrange the cards to show representative organisms in each habitat. When all cards have been
attached to the base material, draw lines to
indicate trophic (feeding) relationships between
these organisms.
5. Lead a discussion of the food web the students
have created. What is the source of primary
production in each habitat? What would the
students infer about the relative abundance
of each trophic level? In the simplest analysis,
organisms at lower trophic levels (primary producers and primary consumers) must be more
abundant than those on higher trophic levels. If
this does not appear to be true, then there must
be additional energy sources for the higher
trophic levels (for example, some secondary
or tertiary predators may feed in more than
one habitat. Considering that the abyssal plain
covers about half of the Earth’s surface, and
is largely unexplored, how might the students’
ocean food web change with further exploration?
The Bridge Connection
www.vims.edu/bridge/ – Click on “Biology” in the
the navigation menu to the left, then “Plankton,” then
“Phytoplankton” for resources on ocean food
webs. Click on “Ecology” then “Deep Sea” for
resources on deep-sea communities.
The “Me” Connection
Have students write a short essay describing their
personal position in a food web, and how they
could adapt if their source of primary production
were no longer available.
Connections to Other Subjects
English/Language Arts, Earth Science
Assessment
Results and presentation of the research component of this activity provide a basis for group
evaluation. In addition, individual written interpretations of the pooled results may be required
prior to Step 4 to provide a means of individual
assessment.
Extensions
Visit http://oceanexplorer.noaa.gov/explorations/07mexico/welcome.html
to keep up to date with the latest
Expedition to the Deep Slope 2007 discoveries,
and to find out what researchers are learning
about cold-seep communities.
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