Observing Daphnia
Name
Date
STUDENT RESOURCE 1.4
ACTIVITY SHEET
Observing Daphnia, Page 1
30 minutes
Observe the daphnia in your cup.
List two ways you can tell the
adults from the babies:
Objectives
• Students observe daphnia with and without a magnifier.
• Students set up a test vial to study changes in a daphnia
population.
1 Babies are smaller.
2 Babies are brownish.
How do daphnia move?
Materials
For each pair
They move in all directions using their antenna.
Copyright © Houghton Mifflin Company. All Rights Reserved.
Turn an empty cup upside-down. Use
a dropper to catch several large adult
daphnia. Put them on the bottom of
the cup. Tell what the daphnia
look like.
Students should accurately describe the size, shape, color,
structures, and other characteristics of daphnia.
Student Resource 1.4, Page 1 (p. 16)
Name
Date
Observing Daphnia, Page 2
STUDENT RESOURCE 1.4
ACTIVITY SHEET
Dates
b
a
b
a
b
a
b
a
b
Predict what will happen to the daphnia population.
The population will get larger as babies are born.
Copyright © Houghton Mifflin Company. All Rights Reserved.
dropper
1
cup (large) containing aged
*water and daphnia
1
empty cup
2
magnifiers
1
vial containing aged *water
1
vial lid
• 1.5 Counting Daphnia
Populations
Inquiry Focus
• Observe
Draw an adult daphnia. Show what is inside it.
AQUARIUM HABITATS • SECTION 1 OBSERVING DAPHNIA • 17
Student Resource 1.4, Page 2 (p. 17)
1
cup (large) containing aged
*water and daphnia
1
dropper
1
empty cup
1
lamp with light bulb
*Not provided in kit
Use the dropper to put five large adult daphnia in the
vial. Pick ones that you think will have babies. Observe
the vial with a magnifier to be sure there are only five
adults and no babies. Put today’s date in the first date
box. Record the number of adults and babies in your
vial. Use a for adults and b for babies.
a
1
Student Resources
• 1.4 Observing Daphnia,
Pages 1 and 2
For the teacher
16 • AQUARIUM HABITATS • SECTION 1 OBSERVING DAPHNIA
Number
of adults
5 a0b
and
babies
Pairs
In Advance
• Each pair of students will need one vial and one large cup. Number
the vial lids consecutively, and fill each vial three-fourths full of
aged water. Fill each cup half full of aged water.
• Just before students begin this activity, pour some daphnia into
each cup of aged water. Do not use a dip net with the daphnia, as
they cannot survive out of water.
1. Distribute materials.
Make copies of Student Resource 1.4, Observing
Daphnia, Pages 1 and 2, and distribute to students.
Give each pair the materials listed above.
2. Students observe daphnia without
magnifiers.
Have students observe the daphnia without using a
magnifier. Ask: How can you tell the babies from
the adults? (The babies are tiny and move rapidly.)
SECTION 1 OBSERVING DAPHNIA • 7
Observing Daphnia (continued)
Have students estimate the number of adults and babies
in their cup. Tell students that daphnia, also called
water fleas, live in freshwater habitats. Have students
observe and describe how the daphnia move.
3. Students use magnifiers to view daphnia.
Turn a cup upside-down, and show students how to put
a drop of water with one large daphnia in the indentation on the cup’s bottom. Explain that you have made
a viewing platform to use with the magnifier. Have students capture one large daphnia in a dropper and place
the daphnia with some water on an inverted cup. Have
students observe the daphnia with magnifiers.
A Viewing platform
4.Students record observations.
Have students record their observations on the Observing Daphnia Resource page. Tell them to wait until the
next activity to draw the daphnia.
Name
5. Prepare for population study.
Have students use the dropper to carefully transfer five
large daphnia with eggs from the cup to the vial. Tell
them to check the vial to make sure it does not contain
any baby daphnia. If it does, have them use the dropper to remove the babies and put them back in the cup.
Direct students to put the numbered lid securely on the
vial. Students should record the number of daphnia in
the vial on the Observing Daphnia Resource page.
Date
12
11
10
9
Key: a = adults; b = babies
end
18 • AQUARIUM HABITATS • SECTION 1 OBSERVING DAPHNIA
Student Resource Page 1.5 (p. 18)
8 • EXPERIENCE SCIENCE
Copyright © Houghton Mifflin Company. All Rights Reserved.
8
7
5a
0b
start
Vial Numbers
6
5
4
3
2
Date/ Time
1
Counting Daphnia Populations
13
14
15
16
STUDENT RESOURCE 1.5
INFORMATION SHEET
6. Record the class daphnia population.
Make a transparency of Student Resource 1.5, Counting
Daphnia Populations, and project it for the class. Write
the date and time in the first box of the first column.
Ask each pair of students to report the number of
daphnia in their vial. Write each pair’s population on
the transparency, using the following key: a for adult,
and b for baby. This first entry should be 5a/0b. Tell students they will be counting their daphnia populations
twice a day for the next three days.
7. Students predict population changes.
Ask: What do you think will happen to the population of daphnia in your vial? (The population will
increase as babies are born.) Have students write their
predictions on the Observing Daphnia Resource page.
Observing Daphnia (continued)
8. Maintain the vials.
Keep the vials at room temperature, preferably near
a lighted lamp or direct sunlight. Adult daphnia can
produce eggs and give birth every four days. The first
babies will be born in about two hours, so you should
begin Section 2 on the same day, if possible.
Assessment
Lead students to think about the needs of living
things. Ask: What do daphnia need to survive? (food,
water, air, space, warm temperature)
Name
Date
Daphnia Body Parts
STUDENT RESOURCE 1.6
INFORMATION SHEET
Esophagus
Observing Daphnia
with a Microscope
Heart
Cells
30 minutes
Food
tube
Eye
Eggs
Mouth
Objectives
• Students use a microscope to observe daphnia.
• Students describe daphnia structures and behavior.
Antenna
Legs
Babies
are born
live
Filter
hairs
Copyright © Houghton Mifflin Company. All Rights Reserved.
Small Groups
Carapace
(shell)
Materials
For each group
1
Anus
Cells
1
Compound
eye with
optic nerve
depression microscope
slide with single daphnia and aged *water
*microscope
Student Resources
• 1.4 Observing Daphnia,
Page 2 from Investigate 2
• 1.6 Daphnia Body Parts
Inquiry Focus
• Communicate
For the teacher
AQUARIUM HABITATS • SECTION 1 OBSERVING DAPHNIA • 19
Student Resource 1.6 (p. 19)
•
*algae water
•
*video/microscope
projection system
(optional)
*Not provided in kit
Teaching Tip
As an alternative to several microscopes, you could use a video/
microscope projection system to
project the daphnia to the entire
class on a television screen.
In Advance
Prepare one depression slide for each pair of students, as follows:
Use a dropper to capture one large daphnia with eggs. Put it with a
drop of water on the center of the slide. Daphnia are easier to observe
when they are moving slowly in water. Remove excess water from the
slide to slow the daphnia, leaving only enough water to keep it alive.
SECTION 1 OBSERVING DAPHNIA • 9
Observing Daphnia with a Microscope (continued)
1. Students use microscopes to observe daphnia.
Have each group of students observe the daphnia with a
microscope. If you do not have microscopes use magnifiers.
2. Students discuss observations.
Make a transparency of Student Resource 1.6, Daphnia
Body Parts, and project it for the class. Ask: What do
you see inside the daphnia? (Daphnia have a clear
shell, or carapace, that is separated at the legs and
abdomen so that food and water can enter and babies
can be born.)
A Daphnia
Safety
Review how to handle and use a
microscope and glass slides with
students.
Teaching Tip
Throughout this activity, add
drops of aged water to the slides
as needed. Daphnia cannot live
without water.
3. Students observe daphnia’s eyes.
Ask: How many eyes does the daphnia have? (one)
Explain that the eye has 18 lobes and 3 muscles that
constantly rotate it. Daphnia can only see light, not
movement. Point out the optic nerve.
4.Students describe daphnia movement.
Point out the antennae, which are attached to the
daphnia’s head. Ask students to describe the antennae.
(They are jointed, forked, and hairy.) Ask: How do the
antennae help the daphnia move? (The antennae
move in all directions, jerking the daphnia through the
water.)
5. Explain daphnia reproduction.
Have students find the brood pouch above the digestive
tube. Tell students to count the eggs (brown spheres)
in the pouch. Tell them that the eggs hatch inside the
daphnia; this may happen as you watch. The babies
(oval gray shapes) begin moving their antennae, pushing to get out of the parent. Point out that the shell is
open along the lower edge. Healthy daphnia may have
babies every four days and they can carry as many as
40 eggs. Usually, however, they carry three to six eggs.
In a poor environment, they stop producing eggs.
6. Discuss male and female daphnia.
Tell students that all the daphnia the class has are
probably females. Explain that daphnia reproduce
asexually, with only one parent. Only when their
environment gets cold or unhealthy do daphnia
produce male and female babies. They reproduce
(mate), producing eggs with hard shells. These eggs
overwinter on the bottom of the pond and hatch in the
spring. This may happen in your classroom if you try to
raise daphnia. You will see two huge dark eggs in the
daphnia. This means there are males in the water and
mating has occurred.
10 • EXPERIENCE SCIENCE
Observing Daphnia with a Microscope (continued)
Name
Date
Observing Daphnia, Page 2
STUDENT RESOURCE 1.4
ACTIVITY SHEET
Use the dropper to put five large adult daphnia in the
vial. Pick ones that you think will have babies. Observe
the vial with a magnifier to be sure there are only five
adults and no babies. Put today’s date in the first date
box. Record the number of adults and babies in your
vial. Use a for adults and b for babies.
Dates
Number
of adults
5 a0b
and
babies
a
b
a
b
a
b
a
b
a
b
Predict what will happen to the daphnia population.
Copyright © Houghton Mifflin Company. All Rights Reserved.
The population will get larger as babies are born.
Draw an adult daphnia. Show what is inside it.
Drawing should resemble the diagram on the Daphnia
Body Parts Resource Page.
AQUARIUM HABITATS • SECTION 1 OBSERVING DAPHNIA • 17
Student Resource 1.4, Page 2, from
Investigate 2
7. Students observe daphnia eating.
Add a drop of algae water to each group’s slide. Let
students observe the daphnia eating the algae. Ask:
How do daphnia eat? (Daphnia have 10 pairs of legs
that constantly move, circulating water and food into
the mouth.) Point out the dark line in the daphnia’s
body. Tell students that this line is the digestive tube.
When the daphnia have digested their food, they
eliminate waste through the anus with a thrust of their
long, bumpy abdomen.
8. Students describe daphnia cells.
Have students adjust the microscopes to a stronger
magnification. Tell them to focus on the daphnia’s
“face” and view the cells. Ask: What do the cells look
like? (tiny rectangles) Remind students that all living
things are made of cells.
9. Students observe a daphnia’s heart.
Point out the daphnia’s heart on the diagram, along
the back near the brood sack. Ask: What is the heart
doing? (It is beating or pumping blood.) Tell students
that the heart pumps blood all through the daphnia’s
body. The blood then reenters the heart and picks up
oxygen. Healthy daphnia are orange; this is a sign that
their habitat has lots of oxygen. Clear daphnia are not
as healthy.
10. Students draw daphnia.
Distribute students’ copies of the Observing Daphnia,
Page 2 Resource page. Have students add drawings of
the daphnia and label its body parts.
Assessment
Ask: How do daphnia use their antennae and
their legs? (They use their antennae to move through the
water. They use their legs to move water and food into
the mouth.)
SECTION 1 OBSERVING DAPHNIA • 11