Earthworms, Symbiosis and Civilizations

Earthworms, Symbiosis and Civilizations By Stephen Greene

Target Audience: High School Biology / Environmental Science

Goal: To make connections between concepts in biology, agricultural practices and
the development of human civilizations.

Objectives or Desired Outcomes: What skills or knowledge do you want your
students to come away with?

 Be able to describe the nitrogen cycle
 Be able to describe the symbiotic relationship between

leguminous plants and nitrogen-fixing bacteria
 Understand and apply the scientific process to answer a question

about the relationship between legumes and earthworms.
 Be able to explain why the development of a civilization might

have been facilitated by the presence of earthworms in soils.
 Be able to explain the reasons for using leguminous plants for

cover crops and apply that understanding in the field.

Vermont State Standards:

Life Science

S9-12:35 (DOK 2)

Students demonstrate their understanding of Food Webs in an
Ecosystem by…

Tracing the cycling of matter (e.g. carbon compounds, nitrogen

compounds)

S9-12:36 (DOK 3)

Students demonstrate their understanding of Equilibrium in an
Ecosystem by…

Designing an investigation to compare a natural system with one altered

by human activities

S9-12:37 (DOK 3)

Students demonstrate their understanding of Recycling in an Ecosystem
by…

Developing and explaining a model that shows the recycling of inorganic

compounds within a natural ecosystem

Earth Science

S9-12:46 (DOK 3) Students demonstrate their understanding of
Processes and Change over Time within Earth Systems by...

explaining the processes by which elements (e.g., carbon, nitrogen, oxygen
atoms) move through the earth’s reservoirs

S9-12:49 (DOK 3) Students demonstrate their understanding of
Processes and Change within Natural Resources by ...

Comparing the availability of natural resources and the impact of different
management plans

S9-12:3 (DOK 3) Students demonstrate their understanding of
EXPERIMENTAL DESIGN

Social Studies

SS9-12:12 Students show understanding of human interaction with the
environment over time by…
Analyzing multiple factors in the interaction of humans and the environment

Timing: This Unit Plan will require several weeks to complete.

Materials Needed:

Quadrat squares, 1 meter
Mustard powder
Glass aquarium
Poster board and art markers
Large plastic pots with soil (three per student group)
White Clover seed (Amount depends on garden size)
Triple-beam balance scales
Garden rakes
Mulch materials (straw, dried leaves, grass clippings)

Procedure:

Step One: Earthworms and Civilizations

 Students will read “Earthworm” chapter in What on Earth Evolved and discuss
Andre Voisin’s idea that civilizations arose in areas with high populations of
earthworms. (Loyd, 93 - 96) (Stewart 144 - 147)

 Students will locate on a map and make comparisons between the geographic
centers of early civilizations, Mesopotamia, the Nile and the Indus river valleys.

 Students will compare earthworm population densities in moist bottomlands
to those in well-drained uplands using mustard powder technique. Refer to
website referenced below for lab protocols. (Univ. of Minnesota)

 Students will use harvested worms to set up a “worm observatory” in class.
(UMN)

Step Two: Nitrogen Cycle –
 Students will read “Rhizobia” chapter in What on Earth Evolved and
demonstrate their understanding of the nitrogen cycle by designing a poster
that describes the basic steps the nitrogen cycle. (Loyd)

Step Three: Symbiosis

 Students will demonstrate their understanding of the concept of symbiosis by
completing the Symbiosis in Agriculture worksheet. (OK Coop. Ext.)

 Students will use earthworms from the worm observatory to design an
experiment answering the question “Are earthworms symbiotic with terrestrial
plants?”, comparing the growth of legumes (white clover) in soils with and
without the presence of earthworm populations. (Stewart)

Step Four:
 Students will collect data on biomass production by white clover under the
different growing conditions and write up the results using proper lab report
format with graphs to show quantifiable results.

Step Five: Green manure
 Students will apply the lessons learned by sowing white clover cover crop and
mulch to encourage growth of earthworm populations in the garden.

Student / Lesson Evaluation: Student work will be evaluated based on completion
of on-going class work and the submission of a final lab report that discusses
concepts learned. A standard lab report rubric will be applied.

Resources:

Symbiosis in Agriculture: Oklahoma Cooperative Extension Service and the Oklahoma
State Department of Education. (http://agweb.okstate.edu/fourh/aitc/index.html)

Christopher Loyd, What on Earth Evolved…In Brief: 100 Species that have Changed
the World (London, Bloomsbury) 2010, pages 30 – 33 and 93 – 96.

Rhizobia A bacterium that accounts for the establishment of successful

civilizations, pages 30 – 33

Earthworm: Subterranean wriggler whose constant burrowing fertilizes the
soil, pages 93 -96

Amy Stewart, The Earth Moved (Algonquin Books) 2004, pages 133 -134.

University of Minnesota – Sampling protocol for earthworms
http://www.nrri.umn.edu/worms/research/methods.html (2012)

Background Information:

Daniel Hillel, Out of the Earth: Civilization and the Life of the Soil (University of
California Press) 1992

Lab Report Rubric

Lab: ______________________________ Student:________________________

Category Superior Proficient Fair Needs
Improvement
Format Double-spaced Minor deviation Significant
10 pts. 12 pt. font from the deviation from Complete lack of
Abstract Headings in bold required format the required attention to
10 pts. Result provided format. required format.
in graphic form States the reason
Introduction for the research, Fails to state one Fails to state some
Hypothesis Clearly states the the methods of the following: of the following: the
reason for the used, the results the reason for reason for the
20 pts. research, the and important the research, the research, the
methods used, conclusions methods used, methods used, the
Materials & the results and drawn from the the results or results or important
Procedure important investigation. important conclusions drawn
conclusions conclusions from the
15 pts. drawn from the drawn from the investigation.
Results investigation. investigation.
20 pts. No background No background
Good Some information / information /
Conclusion background background observations observations
25 pts. information / information / provided. A provided.
observations observations prediction that Hypothesis is not a
provided. A provided. A attempts to draw prediction, fails t
well-stated prediction that a correlation correlate the
prediction that clearly draws a between the variables or is
clearly draws a correlation variables and is untestable.
correlation between the testable.
between specific variables and is Experiment is not
variables and is testable. Experiment is explained in a way
testable. not explained in that can be
Explains what a way that would understood.
Clearly explains was done during make it
what was done the experiment repeatable by Results do not use
during the in a way that another student. units of measure
experiment in a would make it and or graphs,
way that makes repeatable. Results are tables or charts.
it easily presented using
repeatable. Results are graphs, tables or Discussion does not
presented using charts where include an
Results are correct units of possible. explanation of
clearly presented measure, and results .
using correct graphs, tables or Discussion
units of measure charts where includes an
and neat graphs, possible. explanation of
tables or charts Discussion results .
where possible. includes a clear
explanation of
Discussion results that can
includes a clear be supported by
explanation of evidence and
resultsthat can possible errors.
be supported by
evidence,
possible errors,
and next steps.