of Seed Dispersal
Related National Standards
Tools and Materials Needed
Extensions and Adaptations
Plants have evolved many different strategies
for dispersing their seeds: think of "helicopters" on a maple
tree, the fuzzy head of a dandelion, or the tiny, sticky pods that sometimes
attach to your pants, socks, and shoes as you walk through open fields.
In this lesson, students will learn about
one particular method of seed dispersal, through foods that animals
eat. Animals that eat fruits can't digest the seeds of the fruit, which
pass unharmed through the digestive tract and are deposited on the ground
some distance from the original plant. In this activity, students simulate
that process and mark the dispersal location on state and local maps.
By the end of this activity, students
Subjects: Botany, biological
interactions, life science, geography
- Understand why plants have developed
so that many seeds are not digested.
- Understand the need for each plant
to produce numerous seeds.
- Understand that there are differences
in the metabolism of various animals.
Grade Level: Elementary and above.
National Standards from the McRel Standards Database at
- Understands how species depend on
one another and on the environment for survival
- Knows ways in which species interact
and depend on one another in an ecosystem (e.g., producer/consumer,
predator/prey, parasite/host, relationships that are mutually beneficial
and Materials Needed
- A copy of the program "Wild Indonesia:
Creatures of the Island Kingdom" (part 3)
- 2 pound bag of small candies or jellybeans
- Index cards
- Map of the town (USGS topographic
maps would work or many states have county highway maps)
Estimated Time to Complete Lesson
Two days. One class period to watch the
video, determine times for the students and distribute candies. One
class period to plot dispersal on the map and discuss the results.
Plants have developed numerous ways to
disperse their seeds to other areas. One of the common methods is by
using animals that eat the seeds and then pass them through their systems
unharmed when they defecate. This is often a superior way to the whims
of wind, water or other environmental methods.
Plants that use this method tend to have
a number of seeds within the fleshy fruit they produce. When the animal
eats the fruit, the seed enters their system and remains inside as they
travel. Depending upon the metabolism of the creature, and their common
method of locomotion, the seeds may travel hundreds of miles before
they are deposited. The defecated material may also act as a natural
fertilizer in some cases.
Wild Indonesia: Creatures of the Island
6:00 Video shows desolate area
after volcanic eruption. Various plants are starting to grow in the
area. Starting at 7 minutes, it discusses how wind and water distribute
seed. From 7:45 to about 10:00, birds and bats as dispersal
agents are discussed. Students may discuss the dispersal potential of
other animals seen throughout the film.
- Watch the Wild Indonesia: Creatures
of the Island Kingdom video. Stop and discuss the section on seed
dispersal and keep a running track of other animals seen throughout
- Have a student helper take around
the bag of candies and have each student take some. Do not tell them
how many to take. The number of candies represents the number of seeds
eaten by an animal.
- Determine the number of hours between
your current time and the number of hours until 9 p.m. that night.
Using the number of hours until 9 p.m. as the upper limit, have the
students pick a number between 0 and that number. For example, if
it is 10 am, there would be 11 hours until it would be 9 p.m., and
11 would be the upper limit. After the student picks a number, they
should calculate their stop time. For example, if it's 10 a.m. and
a student picks the number 9, his stop time would be 9 hours later,
or 7 p.m. Have each student record his name and stop time, and number
of seeds/candies on the card.
- Students should carry the card and
candies the rest of the day. When they reach their stop time, they
should record their location on the index card; at that time, they
may eat the candies.
- The following day, students are to
mark on the classroom maps their position when their time was up.
Each map mark represents a new colony of the plant. Students that
failed to take note of their position could represent animals that
were eaten during that period and didn't deliver their seed.
- Discuss the amount of dispersal that
occurred and what type of animal in the movie could have carried the
seed that distance. Introduce the idea that different animals may
digest their food at different rates.
Students may be assessed though their
participation in the class discussion and participation in the activity.
Students should write a paragraph explaining how plants using the environment
and how other organisms may disperse seeds that would be scored using
a teacher-made matrix.
- The activity may be repeated on several
different days of the week to look for a change in patterns. If conducted
on Friday, the plant dispersal will be much wider than on a weekday.
Students may calculate the area distance a seed travels or the average
distance by the number of hours traveled.
- If small pebbles are substituted for
the candies, the students can be told to carry the stones with them.
At the appointed time, the students should both note their position
and count the number of stones they have with them. This information
can be used to calculate a percentage of the number of seeds that
survived versus the ones that did not germinate.