Barnacle Lab

barnacles 15k


You will investigate an invertebrate animal called an acorn barnacle.
You will change environmental conditions to see if that affects the barnacle's responses.
This will require careful observation of your barnacles. Use the lab format to report your findings.


Your specific question will depend on what environmental factor
you choose to vary. (Example: How will changing the ________ affect the barnacle's response?)


Barnacles are crustaceans well adapted to a sessile life in
marine intertidal environments. A mobile larval stage attaches itself to a surface and
starts forming 8 to 12 calcareous plates. Two pairs of these plates are movable.
As the tide goes out, barnacles hold a small amount of water in their shells, close the moveable plates and
rest through severe environmental stress until the cool salt water returns.
They can endure changes in salinity, temperature and dryness.
Barnacles also have appendages called cirripodia (cirri) which they extend when under water.
Barnacles vary how quickly they move these cirri. You will be reporting on the effect of varying
environmental conditions on how often the cirri "beat" per minute.
In the 19th century, zoologist Louis Agassiz, said a barnacle is,
"... a little shrimp-like animal, standing on its head in a limestone house kicking food into its mouth."


This is the expected answer to your question.
Example: The rate the barnacle beats its cirri will __________ when the ________ is changed.
Your prediction must be testable with the equipment in our lab.


Make a complete numbered list of the equipment you will need.


Write a step-by-step description of how you will perform the experiment.
Use a list of numbered, short, concise sentences.
Someone else should be able to duplicate your experiment using these instructions.


The data section has three parts:
  1. Data tables with your data.
  2. A graph of your data with the independent variable
    (your environmental factor) on the x-axis
    and the dependent variable on the y-axis (cirri beats).
  3. A diagram (drawing) of one barnacle and the position of its cirri.


Write a short summary of what the data means and attempt to explain it.
Include your question and prediction and discuss how the data supports or
does not support your prediction. Give suggestions for improving your experiment and
areas of further experimentation.