WEB KIE PROJECT

Deformed Frogs!
by theKIE-Roosevelt Curriculum Development Partnership

Project Description

Across North America frogs are being found that have major physical deformities. Scientists have not yet determined why it is happening. There are two major hypotheses that scientists are investigating:
1. The Parasite Hypothesis: A small parasite called a TREMATODE burrows into a tadpole near where the legs will develop. This parasite gets in the way and causes legs to develop incorrectly.

2. The Pesticide Hypothesis: A chemical called METHOPRENE is used by many farmers as a pesticide. After it has been in the sun, this pesticide changes into another chemical that may cause frog deformities.

(FROG PICTURE COURTESY OF DR. STAN SESSIONS)

Cognitive Goals

"Deformed Frogs!" is a debate project which engages students in an examination of a current controversy in science by engaging them with relevant evidence from the Web. It culminates in an informal classroom debate where groups present their arguments about why frogs are being deformed and respond to questions from other students.

Project Prerequisites

This project touches on a number of biological topics. It would be best if students had some familiarity with the concepts before working on this project. The topics touched on by this project include:
• frog development (deformities, hormones, etc.)

• effects of parasites

• environmental pollution

• genetics as it relates to deformities

Teacher Comments

A good approach is to help student engage and grapple with the various biological concepts throughout the project. The debate at the end provides a good forum for helping students to discriminate among the various ideas that will come up while they work on the project.

Deformed Frog Evidence

In the near future, the Deformed Frogs! project will be made available from this page. Until then, we have included a list of the evidence items used in the project:

Background Information -- Start Here

The Frog Deformity Problem

Where Are the Deformed Frogs?

The Minnesota Water Experiment

How Much Deformity Is Normal?

PARASITE HYPOTHESIS: Parasites Interfere With Normal Frog Development

Hypothesis Description

A small parasite called a "trematode" burrows into a tadpole near where the legs will develop. This parasite gets in the way and causes legs to develop incorrectly.

Parasites and Frogs

Looking at Trematodes

The Bead Experiment

The Trematode Life Cycle

Lefty - The Frog

PESTICIDE HYPOTHESIS: A Pesticide Called Methoprene is Deforming Frogs

Hypothesis Description

A chemical called "methoprene" is used by many farmers as a pesticide. After it has been in the sun, this pesticide changes into another chemical that may cause frog deformities.

Pesticides and Frogs

Retinoids Can Make Limbs Grow

Methoprene in Nature

Methoprene and Eye Deformities