Abnormal Amphibians:  An Internet Lesson
Goal:  At the end of this lesson you should be able to
*suggest and support possible causes for frog malformations
*describe how abiotic factors can affect biotic factors in the environment

Overview
Something strange has been happening to the frog and salamander species of the world. Populations are in
decline and some frog populations are showing remarkable abnormalities. The exact causes of these declining
populations and deformations is not entirely known, although a large number of hypotheses have been suggested.

Materials
Malformed Amphibians Worksheet                                  Pictures of Malformed Amphibians
Writing Instrument                                                        Amphibian Web Sites
Computer with Internet Access

Exploration
I.  
Use the following key to classify the
   malformation of the adjacent frog
-->
   
Key to Malformations and Abnormalities



II. Use the adjacent links to answer the following questions: Malformed Amphibs Mysterious Malformed Frogs
                                                                                     The Case of the Disappearing Frogs
1.  What is the difference between a deformation and a malformation?  Give an example of each.

2.  Give at least one piece of evidence that supports AND refutes the following possible causes of malformation

Cause                                  Supporting Evidence                                 Refuting Evidence

UV Radiation

Environmental toxins

Parasites

Predation

Genetic Mutation


3. Why do you think these malformations happening to frogs and not to reptiles?


III. Further Exploration
Freaky Frog FAQs                          A Thousand Friends of Frogs

Explanation :
Abnormal amphibians have been in the eye of the media since a group of children from Minnesota caught some
malformed northern leopard frogs (Rana pipiens) in 1995.  However, although the frequency of abnormal
amphibian reports have increased in the past few years, these types of malformations have been reported in 24 of
the United States since 1740.  Thirty-three amphibian species have apparently been involved, and it is interesting
to note that southwestern states are not represented by accounts of abnormalities and that the majority of reports
fall within a broad band across the mid-northern United States.  Many natural and anthropogenic causes have
been sited, including: parasite infestation, toxin contamination (e.g., biocides, heavy metals, acidification),
predation, UV-B radiation, radioactive salts, ground-level ozone, excessive heating of eggs, cosmic rays and
reformulated gasoline. Of these, the parasite hypothesis seems to have gathered a large amount of supportive
evidence.  If the parasite hypothesis proves true, then humans have very little to fear in the way of environmental
effects and bioaccumulation, but then again, COULD we be incorrect and SHOULD we be concerned?  What do
YOU think?

Take Action :            Action Central                Uncle Frog Wants You
What are 5 things a student like you can do [this month]to help remedy this problem?
1.
2.
3.
4.
5.
Pick one of the above actions, and bring documentation that you have performed it by Earthday, April 22

EC:
Find a map of the United States and mark where abnormal amphibs have been found.  Do you see a trend?  What
is a possible hypothesis for what you see?
Invitation :What do you think happened to these frogs [above]?  Brainstorm at least 3 possibilities.
1.
2.
3.