1
Lesson Two – The Needs of Living Things
Science on the Leading Edge (S.O.L.E.)
-
LESSON TWO - The Needs of Living Things
Overview:
Students will focus on survival needs of organisms, and learn about the undersea
ecosystems found at each of the NEPTUNE Canada Nodes researched in the
previous lesson.
Duration:
1 - 2 classroom sessions
Objectives:
•
•
•
Students will…
•
Vocabulary:
learn about the survival needs of living things.
be able to describe the process of photosynthesis and chemosynthesis.
be able to describe examples of symbiotic relationships, and understand the
different types of symbiosis.
assess how each of the NEPTUNE Canada Node ecosystems provide the
organisms that live there with the requirements for survival.
Organism – a living thing, such as a plant or an animal.
Species – each different type of organism. Organisms of the same species can
mate and reproduce fertile off-spring.
Population – all the members of one particular species living in a given area.
Community – a group that is made up of two or more populations of different
species living together in an ecosystem.
Ecosystem – the network of interactions that link together the living and nonliving parts of an environment.
Survival Needs –organisms must have their basic needs met in order to survive energy source, water, shelter, and oxygen.
Habitat – the physical space where a certain species lives. A species of plant or
animal can only live in a habitat where its survival needs are met.
Limiting Factor – any part of the non-living environment that determines whether
or not an organism can survive, including physical barriers, sunlight, water,
temperature, and soil.
Producer – organisms that can make their own food.
Photosynthesis – the process in which the sun’s energy is used to produce sugars
from carbon dioxide and water, with oxygen released in the process.
Chemosynthesis – the process in which chemicals are the energy source to
produce sugars from carbon dioxide and water.
Symbiosis – literally means “living together”. When two organisms interact
together in such a way as to benefit one or both of the organisms.
Predator - an organism that hunts another living thing for food.
Prey - an organism that is hunted by a predator.
Mutualism - a close relationship between two organisms in which both organisms
benefit (a type of symbiosis).
Parasitism - a relationship between two organisms in which one is harmed and the
other benefits (a type of symbiosis).
Parasite - an organism that derives nutrition from a host causing harm to the host
Commensalism - a relationship in which two organisms live together; one benefits
while the other is unaffected (a type of symbiosis).
Symbiont – an organism living “symbiotically” is a symbiont.
Endosymbiont - a symbiont that lives inside another organism (“endo” meaning
inside).
Trophosome – the organ inside some hot vent tubeworms that contain the
symbiont microbes. These “gutless worms” have trophosomes in the place of
stomachs and “plumes” instead of mouths!
The key words provided are integral to this lesson plan. If the ecology terminology has not already
been covered in your class, you will need to teach the material prior to this lesson.
British Columbia PLO’s:
• Grade 7 Life Sciences – Ecosystems
Background:
1. Ecology
An ecosystem is a network of interactions that link the living and non-living parts of an environment.
The living parts of the ecosystem include the organisms, such as the plants and animals that live
within the environment. Each different type of organism is known as a species. All the members of
one particular species in a give area are called a population. When two or more populations of
different species live in the same area, they form a community. The non-living parts of the ecosystem
include elements such as sunlight, rain and snow, sediment, rock, and temperature.
2. Energy Sources: Photosynthesis and Chemosynthesis
All living things need energy. People and other animals get their energy from the food they eat.
However, neither the plants on land nor the microbes that live around hydrothermal vents eat food.
Instead, they make their own food. Organisms that make their own food are called producers.
3
Lesson Two – The Needs of Living Things
Science on the Leading Edge (S.O.L.E.)
-
Producers such as plants, seaweeds, and phytoplankton harness energy from the sun to make sugars.
This process is called photosynthesis. Organisms that are photosynthetic use the sun’s energy to
produce simple sugars from carbon dioxide and water, releasing oxygen in the process.
C02 + H2O + sunlight (energy)  sugar (C6H12O6) + O2
One of the major scientific discoveries of the last 100 years is the presence of complex deep-sea
communities that do not depend upon sunlight as their primary source of energy. Hot vent
communities like the one found at the Endeavour Ridge Node, and methane seep communities like the
ones found at the Barkley Canyon Node are two examples of undersea ecosystems that thrive without
sunlight. Instead, these communities get their energy from chemicals through a process called
chemosynthesis. Organisms that are chemosynthetic use chemicals as the energy source to produce
sugars from carbon dioxide, oxygen, and water.
For example, hydrogen sulfide is abundant in the water erupting from hydrothermal vents, and is used
by microbes to produce sugars that are the base of the vent community food chain. These bacteria get
their energy by oxidizing hydrogen sulfide to sulfur:
C02 + O2 + H2S (energy)  sugar (CH2O) + S + H2O
Put into words, carbon dioxide plus oxygen plus hydrogen sulfide makes organic carbon in the form of
CH2O, sulfur, and water. Chemosynthetic bacteria grow on and below the seafloor at hydrothermal
hot vent sites, and are even found growing within other animals found at the vents, such as tubeworms.
Just like hydrothermal hot vents, chemosynthetic bacteria are also the bottom of the food web in cold
seep communities like the one found at the Barkley Canyon Node. Cold seeps are generally found
along continental margins, where hydrogen sulfide, methane and other hydrocarbon-rich fluid seepage
occurs, often in the form of a brine pool. Cold seeps are home to many species of organisms that have
not been found anywhere else on Earth. Similar to the bacteria found at the hot vent sites of
Endeavour Ridge, the bacteria that live at Barkley Canyon process sulfides and methane through
chemosynthesis. The bacteria here form thick bacterial mats, or live in close association with other
organisms.
Instead of photosynthesis, vent ecosystems derive their energy from chemicals in a process called
“chemosynthesis.” Both methods involve an energy source (1), carbon dioxide (2), and water to produce sugars
(3). Photosynthesis gives off oxygen gas as a byproduct, while chemosynthesis produces sulfur (4).
Image courtesy Woods Hole Oceanographic Institution.
Text from Ocean Explorer:
oceanexplorer.noaa.gov/explorations/02fire/background/education/media/ring_candy_chemo_9_12.pdf
The chemistry of a “black smoker.” After seawater seeps into the crust (1), oxygen and potassium (2) and then
calcium, sulfate, and magnesium (3) are removed from the water. As the water begins to heat up (4), sodium,
potassium, and calcium dissolve from the crust. Magma superheats the water, dissolving iron, zinc, copper, and
sulfur (5). The water then rises back to the surface (6), where it mixes with the cold seawater, forming black
metal-sulfide compounds (7).
Image courtesy of Woods Hole Oceanographic Institution.
Text from Ocean Explorer:
oceanexplorer.noaa.gov/explorations/02fire/background/education/media/ring_candy_chemo_9_12.pdf
3. Exploring Symbiosis
If you have poked around in a tide pool, you have probably seen bright green sea anemones that look
more like flowers than animals. The anemone is green because it has an algal partner (or symbiont)
that is green! These giant green anemones, Anthopleura xanthogrammica, are an example of
symbiosis. The anemone provides a secure home for the algae, and the algae make sugars by
photosynthesis for the anemone.
There are three different ways in which organisms can engage in a symbiotic relationship. Mutualism is
a close relationship between two organisms in which both organisms benefit. Parasitism is a
relationship between two organisms in which one is harmed and the other benefits, and commensalism
is a relationship in which two organisms live together where one benefits while the other is unaffected.
In the deep-sea there are many relationships among organisms that may seem strange and unusual to
you. At hot vents and cold seeps, unique food chains were discovered completely reliant on
chemosynthesis. When worms found at hot vents like the Giant Tubeworm, Riftia, were looked at,
biologists found that this worm was “gutless”. It took a while, but what they discovered was a unique
chamber inside the animal, called a trophosome. The trophosome contains microbes that need sulfide
compounds to produce sugars. These sugars are then consumed by the tubeworm. The Giant
Tubeworm and the microbes are so interconnected that they cannot survive without each other. When
hydrothermal venting stops and the tubeworm can no longer provide chemicals to the bacteria, both
organisms die.
Similar symbiotic relationships between tubeworms and microbes, and between clams and microbes
exist at cold seeps like the one found in Barkley Canyon.. Deep-sea clams farm methane-munching
microbes in their guts providing the microbes with methane. The clams then harvest the sugars made
by the microbes, showing another example of producers and consumers living together to meet their
survival needs. Other clams, such as “V” clams (“Vesicomyid Clams”) commonly seen in vent fields
and at cold seeps, live by sucking sulfide through their foot from the mud. Sulfide travels through the
5
Lesson Two – The Needs of Living Things
Science on the Leading Edge (S.O.L.E.)
-
V-clam’s body to the gills where gizzillions of microbes live. The gills absorb oxygen, carbon dioxide
and water giving the bacteria all of the chemical elements they need to produce sugars. For more
information on Cold Seeps and V-clams, check out College of Marine Science: Project Oceanography
http://www.marine.usf.edu/pjocean/packets/sp02/sp02u2p4.pdf- (Cold Seeps and V-Clams.doc)
These are just three examples of symbiosis. In the sea and on land, there are thousands of animals that
have symbiotic relationships.
4. The Needs of Living Things
All organisms must have their basic needs met in order to survive. Organisms live successfully in
ecosystems that supply them with their basic needs, such as food, water, and suitable living conditions.
In general, the survival needs of organisms include an energy source, oxygen, water, and shelter.
The physical space where an organism lives is called its habitat. We have researched the habitats of
three of the NEPTUNE Canada Nodes sites in Lesson One (Folger Passage, Barkley Canyon, and
Endeavour Rideg). For this lesson, we will examine some of the organisms that live in each of the
ecosystems, and assess how their survival needs are met.
Materials:
• Computers with internet access
• Download and print copies of Photosynthesis vs Chemosynthesis Worksheet
• Download and print copies of Symbiotic Relationships Activity (Reference: Adapted from
Ohio Department of Education http://www.edquest.ca/pdf/7final03key.pdf)
• Download and print copy of Organism Lists (for teacher).
• Download and print copies of Critter Card Template.
• Markers or crayons for drawing on Critter Cards
Procedure:
1. Begin by reviewing the key concepts found in this lesson (organism, species, population,
community, ecosystem), giving examples for each. Having the vocabulary list on the board or as
an individual handout for reference during the lesson will be very helpful.
2. Lead a discussion about the essential needs for life. Get them to think about all living things, from
the smallest microbe to their own needs for survival.
3. Using the board, brainstorm with the class to create a concept map outlining their survival needs.
What provides each of the needs? Are their needs inter-connected?
4. Focus on energy source. Introduce photosynthesis, and the importance of organisms that can make
their own food. Ask the class if they can think of any ecosystems that thrive without sunlight as
the energy source.
5. Introduce chemosynthesis, and the idea that ecosystems can exist without sunlight. In these
ecosystems, the organisms that provide the rest of the food web with energy use chemicals as the
energy source to make sugars rather than sunlight. Ensure that the students understand this process
on a basic level.
6. Use the Dive and Discover Website http://www.divediscover.whoi.edu/vents/light.html to compare
and contrast Photosynthesis versus Chemosynthesis. This interactive animation is a great tool to
help your students understand these processes. You can use a computer linked to a LCD projector
at the front of the classroom to go through the steps (1-4) all together, or alternatively get the
students to go through the steps on their own or in small groups at the computer.
7. Task the students to complete the Photosynthesis vs Chemosynthesis Worksheet.
8. Re-visit the site characteristics of each of the NEPTUNE Canada Nodes the students researched in
the previous lesson, and explain that both the Endeavour Ridge Node and the Barkley Canyon
Node are examples of two under-sea habitats that support ecosystems that thrive without sunlight.
The Folger Passage Node is found at much shallower depths, and therefore has photosynthetic
organisms at the base of the food web, like the ones we are familiar with.
9. Using the Background Information on Exploring Symbiosis given above, go over what symbiosis
means with your students, explaining the three ways in which these symbiotic relationships exists.
Optional: Symbiotic Relationships Activity (Reference: Adapted from Ohio Department of Education
http://www.edquest.ca/pdf/7final03key.pdf
• Task the students to complete the Pre-Assignment, the Activity, and the Post-Assignment,
or
• Chose the activities that are most appropriate for you students
10. Re-visit the topic of survival needs of living things. In general, the survival needs of organisms
include an energy source, oxygen, water, and shelter.
11. Divide the class into three groups. Each group should be assigned to one of the NEPTUNE
Canada Nodes (you could use the same groups from the discussion in Lesson One, or form new
groups).
12. Provide each group with a list of organisms found at their underwater ecosystem (download from
SOLE Website - Organism Lists). This copy is for the teacher only, as an aid to help with the
creation of the Critter Cards. Only provide the students with the name of the organism.
13. Get each student to choose one organism from the list, ensuring that there are no duplicate
organisms, and each trophic level (producer, secondary consumer, and tertiary consumer) is
appropriately represented.
14. Using the SOLE Website and other resources on the Web, task the students to go on a quest to
discover the following information about their organism:
• Pictures of the organism
• Common Name
• Scientific Name
• How the organism gets the basic requirements for life: energy, shelter, oxygen, and water
Students should make rough notes and sketches in their notebooks as their research progresses.
Hint: In the underwater ecosystems that we’ve been studying, all the organisms get their need for
oxygen from the water (dissolved). Also, since the organisms are already in water, get the students
to figure out what temperature (hot, cold etc.) and chemical make-up of water they require.
15. Give each student a copy of the Critter Card Template. The students should work on completing a
Critter Card for their organism, including a colour drawing on the front.
7
Lesson Two – The Needs of Living Things
Science on the Leading Edge (S.O.L.E.)
-
16. Follow-up this activity with a discussion of ways in which these unique underwater ecosystems are
able to meet the needs of the organisms that live there.
17. Inform the student that they will be learning about Food Webs and Trophic Levels in the final
lesson (Lesson Three), and adding to their Critter Card. Therefore, they need to keep their Critter
Cards safe from harm until then!
Discussion:
• Open discussion about the ways in which these unique underwater ecosystems are able to
meet the needs of the organisms that live there, include topics such as biotic and abiotic
factors, limiting factors, depth, light, oxygen levels, sulfur levels, metals, energy source,
symbiosis, competition, predator-prey relationships, and reproduction.
• Hold a round-table discussion and/or debate based on what students learned in this lesson
using the following statement: Some scientists believe in the possibility that Earth itself
might have started in the sulfurous cauldron around hot vents. Vent environments minimize
oxygen and radiation, which can damage primitive molecules. They believe that many of
the primordial molecules needed to jump-start life could have formed in the subsurface of
the ocean floor from the interaction of rock and circulating hot water driven by hydrothermal systems (Source: OceanExplorer http://oceanexplorer.noaa.gov)
Extension and Resources:
• ART – engage the students to draw and colour a picture that describes themselves and their
relationship to the ecosystems they live in. Include the elements that they believe are
needed for their own survival.
• for more information on Cold Seeps and V-clams, check out College of Marine Science:
Project Oceanography http://www.marine.usf.edu/pjocean/packets/sp02/sp02u2p4.pdfReferences:
B.C. Science PROBE 7 Textbook, Nelson (2005)
Dive and Discover (Wood’s Hole Oceanographic Institute): http://divediscover.whoi.edu/
NEPTUNE Canada: http://www.neptunecanada.ca (up to date, not as student-friendly)
Wood’s Hole Oceanographic Institute: http://www.whoi.edu/
College of Marine Science: Project Oceanography
http://www.marine.usf.edu/pjocean/packets/sp02/sp02u2p4.pdf-
OceanExplorer http://oceanexplorer.noaa.gov
Ohio Department of Education http://www.edquest.ca/pdf/7final03key.pdf