'Frogs as Bio-Indicators'
|Welcome to the 'Frogs
as Bio-indicators' Science Corner, a feature of the Thousand Friends
of Frogs web site, which deals with the scientific aspects of amphibians
and their environment. Choose from the following areas of interest:
When talking about frogs, toads or salamanders, you will probably have some questions. These are some basic facts about amphibians--frogs, toads, salamanders and caecilians. If you have further questions, check out the 'Frog'-quently Asked Questions section.
Q. What is an amphibian?
A. Frogs, toads, salamanders and caecilians are all amphibians. The word means double life--many species spend part of their life in aquatic (water) and terrestrial (land) environments. Because their skin lacks a shell, scales or outer drier covering, most amphibians live in wet or damp situations to prevent dehydration.
Q. What is metamorphosis?
A. Various animals undergo major changes in their body appearance and
structure as they grow. They undergo meta (change) in their morpho
(form). For instance, frogs lay eggs which grow into tadpoles, which
undergo a dramatic change into froglets and finally grow to be an adult
frog. The key thing in metamorphosis is a rapid, drastic change in form,
for example from the tadpole to the frog.
Q. What is a Bio-indicator?
A. A Bio-indicator is a living (bio means life) creature that is indicating or telling you something about the area that it lives in. It can be something positive (good) or negative (bad). For example, having lots of frogs in an area tells you and scientists that the environment is healthy and complete for the frogs. If for some reason frogs are suddenly missing from an area or their population is declining (shrinking), then this is telling you that their environment is changing. Sometimes bio-indicators can be used to show us that the quality of the air we breathe or water we drink may not be of a high quality.
Q. Why are frogs good bio-indicators?
A. Frogs and other amphibians are good bio-indicators because
Q. How long have amphibians been around?
A. Amphibians have been around for an estimated 350 million years. The earliest known frog appeared about 190 million years ago, during what is known as the late Jurassic period.
Even though we distinguish in general terms between frogs and toads, apart from minor physical differences, frogs and toads are really the same. Herpetologists (scientists who study amphibians and reptiles) refer to frogs and toads as anurans.
All anurans are appropriately called 'frogs' while 'toads' is reserved for specific families of anurans like Bufonidae (a common family of toads in N. America and other parts of the world).
The 14 species of anurans found in Minnesota are grouped into three families: true frogs, treefrogs, and toads. Even though they are placed in three groups, each individual species (types) within each group has its own particular environment (or niche), unique breeding call, and survival mechanism.
Click on the name to get more information and see a photograph of each
frog or toad. Click
here to hear calls of some of Minnesota's frogs and toads. Click
here for A Key to the Anuran Tadpoles of the United States and
What Scientists are saying about Amphibian Populations in Minnesota
Survey Results from
Hundreds of students and citizens have again been assisting the Minnesota Pollution Control Agency (MPCA) gather data on the health of Minnesota's frog population during 1996, 1997 and 1998. Click here for the results of the survey.
Click here for surveying pictures.
Here you can find answers to some of your questions about:
The Life of Frogs and Toads
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