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A Little Bit More

Frogs and toads in general cannot be categorized by outward appearances, but the more common North American species are relatively easy to distinguish. As the poster points out, the order Anura (frogs and toads) is divided into three categories: toads, tree frogs, and true frogs. Initially, attempts to arrange the frogs and toads into meaningful groups were a failure; external differences were not reliable. Not until the latter half of the 19th century, was it determined that the skeletal construction of their pelvic girdles afforded a reliable means of separating the anurans. Today, the structure of the pelvic girdle and type of vertebrae allow herpetologists to categorize these animals.

Toads (family Bufonidae) are common backyard amphibians. They are insectivores, consuming large numbers of insects daily. The most widespread misconception regarding toads is their ability to cause warts on anyone who handles them. In fact, warts on humans are caused by a virus, not by toads. The "warts" on toads are actually skin glands that can exude a mild poison when the toad is alarmed. These skin secretions are effective irritants on mucus membranes (a dog's mouth, for instance) but not on external skin. Despite this poison, some predators do eat toads. Snakes don't seem to be bothered by the secretions, and skunks apparently avoid the poison by rubbing the toad around on the ground until most of its secretions are gone.

Tree Frogs (family Hylidae -HIGH-lih-dee) are small in size, usually in trees, and have camouflage that makes them the least known of the anurans. Many have adhesive discs that make it possible for them to climb. Many kinds can change color or pattern and this makes them difficult to find; it's usually their call that is a clue to their presence. Tree frogs are excellent jumpers. Two species, the Cricket and Chorus Frogs (these are basically ground dwelling) have incredible jumping abilities; Cricket Frogs can jump thirty times their own body length!

True Frogs (family Ranidae) are probably the most often seen amphibians, the ones that usually come to mind when we think of frogs. They're commonly seen along stream and pond banks, although some species do travel considerable distances from water. The true frogs are also good jumpers and some can vault as much as 9 times their own body length.

Activities

Learning about local frogs, tree frogs, and toads plus how to access information

In our information-oriented world, we have to run, just to stay in place! There is an enormous amount of material that has been written on almost any subject you can imagine. With so many people doing research on various subjects each year, new discoveries are written in journals, books, videos, and the internet for professional and public use. As a result, our understanding and knowledge about various organisms is increasing at a rate that is hard to keep up with - yesterday's knowledge is often only partially correct in the light of today's research.

Although we may have excellent information on frogs, for example, in our libraries, within a very short period, this material becomes dated. This student activity is designed to help students understand that it isn't always easy to remain current - it takes a little more effort!

Have the students determine which kinds of true frogs, tree frogs, and toads are found around their community (a current field guide will help with this) and then assign each student or group one of the area's species to find out recent information. The students should be looking for material that is no more than 10 years old and preferably 5 or fewer years old (students will need to look at publication dates for their sources). The students may find information targeted for their specific species OR they may find more general information that pertains to toads, for example - students should look for both. If they find more general information on toads, this can be incorporated into their specific species' research findings.

Each student(s) can write up their findings about their particular animal. Information should include the following if at all possible:

1. Common name (if more than one, list all)
2. Scientific name (genus and species, ie. Homo sapiens)
3. Current range (may want to show a range map of the U.S. or "their" state/province)
4. Information on population status (increases or decreases)
5. Variations within a species (color differences and/or anatomical differences)
6. Recent info on some aspect of their lives - habitat, behavior, food etc.

Key Concepts

Identification, Adaptations and Diversity

Questions

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