AY Honors/Amphibians/Answer Key

1. Describe the life history of some amphibian.

Adventist Youth Honors Answer Book/Nature/Life cycle of a frog

2. Explain the economic value of amphibians.

Amphibians are insect eaters, so they are very valuable for controlling mosquito populations. They are also the preferred dinner for several mammal, bird, fish, and reptile species.

Amphibians are valuable for medical research. They are raised and sold to research institutions.

The larvae of newts and salamanders are sold as fish bait.

Amphibians are closely monitored by ecologists, because they are among the first animals affected by environmental problems such as pollution and the destruction of the ozone layer.

3. Where do toads spend the winter or dry season?

Toads burrow below the frost line and hibernate for the winter. Plant matter actually generates a bit of heat as it decays, so toads prefer areas with plenty of leaf litter and fallen logs.

4. Identify two species of frogs by their sound or imitate the sounds of two different species of frogs.

Smithsonian Folkways Recordings has several frog calls available on CD or for download.

5. How do frogs and toads sing? What makes the noise so loud?

Frogs call by passing air through the larynx in the throat. In most calling frogs, the sound is amplified by one or more vocal sacs, membranes of skin under the throat or on the corner of the mouth that bulge out during the amplification of the call.

Some frogs lack vocal sacs, but these species can still produce a loud call. Their mouths are enlarged and dome-shaped, acting as a resonance chamber that amplifies their call. The body of a guitar does much the same thing, having a large hollow section that causes the sound to resonate inside before escaping to the outside atmosphere.

6. Do one of the following:

IMPORTANT

In the 1990's, amphibian populations in the United States and Canada began a precipitous and mysterious decline. Many frogs were discovered in Minnesota with unexplained deformities, including extra limbs, missing limbs, deformed limbs, and missing eyes. As a result, many species of amphibians are now protected by state and federal laws. When observing wild amphibians, it is extremely important that they not be handled. Doing so can spread disease to these creatures, causing further decline. Before venturing out, make sure your Pathfinders understand and appreciate the danger facing amphibians today. Do not allow your group to capture or otherwise harass them, and do not destroy their environment. Rather than pursuing the two options (a and b) listed for this requirement, it may be wiser to substitute an alternate requirement. One possibility is to have your Pathfinders research the amphibian population crash.

a. Observe a toad in your yard or neighborhood to find out.
(1) Where and when it sleeps,
(2) When it leaves its home for food,
(3) How fast it can travel,
(4) How far it can jump, and as many other interesting things as you can find out about it, and write an essay covering the details requested in the first section of this question.

It is recommended that instead of investigating wild amphibians, the student should research them using other available resources, including the Internet, books, and encyclopedias. It is recognized that observing them in the wild is by far more fascinating, but it also carries the potential to do great harm to the amphibian population. See the notes in section b for more details.

b. Hatch some amphibian eggs and watch them through their growth cycle and write an essay covering the details.

Frog eggs can be purchased from http://www.nilesbio.com/subcat367.html - but only in the spring.

According to Field Guide of Amphibian Larvae and Eggs of Minnesota, Wisconsin, and Iowa, a publication of the U.S. Geological Survey (USGS), "State and federal laws protect amphibians from exploitation. Collection permits are required from the appropriate state or federal authorities before capturing, handling, or collecting amphibians."

It is therefore recommended that you not attempt to collect amphibian eggs on your own. You can download this book as a PDF from the page cited above. Even if you do not live in Minnesota, Wisconsin, or Iowa, the species covered in this book may be indigenous to your area.

The USGS publication further states, "To prevent the spread of disease to native populations, any frogs or salamanders you raise should not be released back into the environment. Lab-raised amphibians can be anesthetized and euthanized with benzocaine or tricaine methanesulfonate (MS 222, Green 2001). If you anticipate difficulty complying with this guidance, you should not undertake raising larvae in captivity."

References

• Wikipedia article on frogs
• Wikipedia article on salamanders
• http://www.wnrmag.com/stories/1996/apr96/frog.htm
• http://www.californiaherps.com/index.html