Transcript Understanding The Scientific Method Using Brine

Understanding The Scientific
Method Using Brine Shrimp
The Scientific Method Made Simple
• Ask a question.
• Gather information about the question.
• Form a hypothesis.
• Test the hypothesis.
• Tell others what you found.
Ask A Question
Why do most of the brine shrimp
gather or cluster towards one end
of the bowl?
Gather Information About The
Question
• Brine shrimp live in salty ponds or lakes
throughout the world.
• When conditions are not good, they form
an egg that survives drought.
• They feed mostly on algae.
• Very few predators
• The adult brine shrimp as compound eyes.
• The larval stage (nauplius) of the brine
shrimp has a simple eyespot.
Great Salt Lake
The Great Salt Lake of
Utah is a terminal lake.
The only way water
leaves the lake is
through evaporation.
ut.usgs.gov
Stages of the Brine Shrimp Life
Cycle
Male
Larva
www.microimaging.ca
webs.lander.edu
Female
scicom.ucsc.edu
Eggs
www.aquariumlife.net
Gather Information Continued
• It is known that many zooplankton
creatures travel to deeper waters by day
and come up to the surface at night.
• Many of these animals have simple eyes
for detecting light.
• The orientation towards or away from light
is called, phototaxis.
Form a Hypothesis
• If zooplankton of the ocean seem to go
away from light to avoid predators, what
would brine shrimp do if predation is not a
problem?
• Is light a stimulus that affects their
response?
• Would they have the same response as
zooplankton of the ocean?
A Possible Hypothesis
If I shine a light on one side of
the bowl, the brine shrimp will
move towards the light.
Another Hypothesis
If I shine a light on the bowl, the
brine shrimp will swim away from
the light.
Test The Hypothesis
Trial#
Direction
1
North
Orientation Comments
+ or +
2
South
+
3
East
+
4
West
+
What do the data show?
30
25
20
Positive
Negative
15
10
5
0
North
South
East
West
Analyze Your Data and Conclusion
• The data shows that no matter which
direction the light was held, most of the
brine shrimp oriented themselves towards
the light.
• The data supports the hypothesis. The
brine shrimp did move towards the light.
Tell Others What You Found
www.mrg-online.com
The Next Step-Why?
• Some students came to the conclusion
that the brine shrimp were attracted to
the heat of the flashlight.
• This could be a new hypothesis to test.
• Have the students look at the background
information they have collected and see if
they can figure out why.
Possible Reasons
• Few predators, no need to hide
• Lost of habitat through evaporation
• Food source is near the surface
• Possible reason-This species has a limited
life with no time to migrate up and down
in the water column. They must eat and
grow to reach the egg stage. That is the
only way this species can survive their
biggest threat, drought!