Mar/15/2016
Amphibians / Animals / Frogs / Habitats / Life Cycles / Toads

Amazing Amphibians: Frogs and Toads

Wrapping up an activity post on princesses, I began thinking about frogs. Princesses kissing frogs? It is fun to contemplate the message of that story. We know the princess’s side of the story, now let’s consider the frog’s.

As winter winds down and there are signs of spring, don’t you start anticipating that first tadpole?

Amphibians are a rare topic in children’s discussions of animals. Most existing kindergarten and elementary curricula and on-line sources focus on birds, mammals, and the occasional insect. So let’s step outside of our comfort zones and explore these really unique creatures whose life cycles and place in the food web offer some new and different lessons about animals.

For this post, we’ll focus on the amphibians, frogs and toads. We’ll save salamanders (and newts) for another post. Yet another order of amphibians I have not mentioned is called caecilians. These are worm-like and found in the tropics. I think I will skip these for now and leave it you’re your budding herpetologist to discover these on her own if her interest level is deep.

Amphibians, and especially frogs and toads, figure prominently in children’s stories, both historical and contemporary. So take some time to familiarize yourself and your child with these new animal friends.

There are lots of avenues for exploring frogs and toads. Follow your child’s lead and let him dictate where to begin, or what topics to look more closely at. The following represent suggestions for how you might guide his curiosity. Use these suggestions to initiate conversations or explorations. – today and days to come.

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Questions

Scientific investigations begin with questions, and those questions will determine your methods of inquiry.

 

Let your child figure out his own answers, but in the meantime, the correct answers are provided below so you can drop some great hints!

 

What does the word amphibian mean?

 

(Just in Case: The word amphibian translates from a Greek word to roughly mean “both kinds of life” or “double life.” Virtually all amphibians spend the first part of their life cycle in water, and then the remainder primarily on land. Other animals live both in water and on land, such as seals, walruses, and otters, but they do not start out as eggs in water and then experience a significant metamorphosis.)

 

 

 

What do frogs and toads look like? Feel like? Smell like? Taste like (in the case of frogs, and if you are so inclined to eat one)?

 

Where do these animals live? What are those ecosystems like that they inhabit?

 

What is their life cycle?

 

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Do they have predators? What might these be?

 

What do they eat or prey on in their various life cycle stages?

 

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Observe

Unless you have a pet frog or toad, your best observations may have to be at a pet store or a zoo.

 

If you happen to live near a lake, pond or stream you may be able to see them in their natural habitat. If it is the right time of year go on a frog hunt. Take along a container with deep sides. If the container is too shallow, the frog can escape. Cloth to lay over the top might also be helpful. A burlap-type sack can also work. You can try to capture the frog with your hands, but a net will probably be best. Talk with your child about how to capture a frog so as not to injure it, or be gentle and careful.

 

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If successful, look closely at the frog (suggestions below). If you are not successful at catching a frog, at least take some time to look at its’ habitat or where it lives. What types of plants are around? Are there plants in the water that can serve as safe cover? Can you see bugs that a frog might feed on? How deep is the water? Invite your child to sketch or photograph the area, as these activities help to focus observations.

 

Alternatively, find some tadpoles and let them transform into frogs right before your eyes. The best places to look are in shallow, still water near the banks of creeks or ponds. Here is some advice about capturing and raising tadpoles. http://allaboutfrogs.org/info/tadpoles/

You can also order tadpoles online.

 

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Another alternative is to purchase toy frogs. There are some authentic looking toy frogs in packages of 8 – 12, available for as little as three dollars. This might be a fun option for discovery now and future play.

 

A final option is to examine a series of good photos or illustrations from a field guide, particularly if these are placed on index cards so they can travel with your child in the car or when walking outdoors. These can still inspire close observations, particularly if you are involved and share in examining those photos.

 

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Frogs and toads are both part of the order Anura (frog), and there are no taxonomic differences between them. There are over 6400 species, with 580 true toads. So as you might guess from these numbers, frogs make up the largest number of species in the order and are more prevalent than toads.

 

The following categories represent areas of interest your child may demonstrate about these creatures. Hopefully, you can determine what aspect of this animal your child is most interested in and discuss that. Consider these other topics to bring up in later discussions.

 

RANGE: Frogs and toads are found worldwide wherever there is fresh water (not salt water as in the oceans). And I mean all over the world even in subarctic regions. The only part of the world where they do not live is Antarctica. Most frogs, however, and the greatest number of different species, are concentrated in tropical rainforests. Also, since fresh water is a critical part of their life cycle, environments where fresh water is very scarce or virtually absent isn’t very favorable. Do you have a map or globe that you and your child can take a look at and figure out where frogs DON’T live (Antartica)? Can you point out tropical areas such as around the Amazon where you find the most species of frogs?

 

Maybe a good place to start is to examine the most colorful frogs if you think that this will capture your child’s imagination. Or start with the frog that is just outside of your back door if you are so lucky.

 

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Ask your child what he sees about the frog (live, toy, or photo) and describe it to you. If he gets stuck, consider the following options.

 

LEGS AND FEET: Examine its legs and feet. How many are there? Find the language to describe them. The hind legs are long and with obvious muscles (How long relative to the body length? About twice as long?). What about their front legs? (Obviously shorter).

 

What do their feet look like? Frogs feet are webbed, but the amount of webbing between their toes depends on where the frog lives. If they live primarily in water, do you think would they have more or less webbing (More)? Land-dwelling frogs have less webbing (Why? Because they don’t need the webbing for swimming). Some tree-dwelling frogs have more webbing that acts as a kind of parachute if they were to fall from the tree. They can spread their toes and glide to earth. Those tree-dwelling frogs also have pads on their feet that help them climb.

 

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Frogs also burrow or dig with their feet. See any claws? (You should not).

 

Frogs can jump great distances, thus all those muscles in their legs. This is probably a good skill to have if you are escaping a predator.

 

EYES: Where are their eyes? Why are the eyes so large and so prominent? They are positioned on the top of the head and can see almost in all directions or a full circle, allowing frogs to avoid being eaten by their predators and to more easily capture their own meals, such as insects. Eyes on the top of the head also allow frogs to float in the water with only their eyes looking out like tiny periscopes, but their bodies remain submerged and protected.

 

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A frog’s eyes can do something remarkable. They can sink down in its head to assist in swallowing, and helping food along toward the stomach.

 

Frogs also have something we don’t have or three eyelids. One of those is transparent and specially designed to protect the eye underwater. If you have a live frog, what happens when it blinks?

 

MOUTH: What does a frog’s mouth look like? Help your child finds the language to describe a frog’s mouth. Big and wide should allow it to do what? (Eat bigger bugs and make bigger noises.)

 

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NOSE: Is there a nose? Are there nostrils (yes but tiny). Or how does a frog breathe? A frog has lungs and can breathe through its nose. BUT, it can also breathe or absorb oxygen through its skin!

 

TAIL: Is there a tail? (Not on the adult frog)

EARS: Are there ears? Frogs have a very good sense of hearing and can hear both on land and underwater. To find their ears, or rather an eardrum, look behind their eyes.

CHIN: A photo may have to do here unless you can observe a frog for a long time and it is willing to make a noise. Those chins can billow out forming a significant balloon-like feature under the chin, or sometimes one on each side.

 

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EGGS: So far these instructions assume your child has been observing an adult frog. The frog’s life cycle begins as an egg; an egg is floating in a pond or still water with its siblings in a gelatinous mass of a couple hundred and even thousands of eggs (called a frogspawn). A toad’s eggs are linked together, but more like a long strand as opposed to a mass. Why so many? Predators like to eat frogs’ eggs. Some frog species’ eggs are free floating, so as usual, there are exceptions.

The egg is surrounded by a gelatinous material, which serves what purpose? (Protects and feeds it and also allows for exchange of oxygen). A frog’s egg is not distinct from a hen’s egg with the same basic parts. However, frog’s eggs lack an outer protective covering or “shells”.

 

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The egg hatches and a tadpole or polliwog swims out. The tadpole has a relatively large round head attached to a tail that propels it through the water. As it lives in water, it is breathing with gills. This ability to get oxygen out of the water by using its gills during this stage of its life cycle is similar to fishes and their gills.

As the tadpole grows, it also begins to sprout hind legs, and later front legs appear while the tail gradually disappears. While limbs are appearing, the head is changing size, and the eyes are moving upwards. Finally, the internal gills give way to lungs, and the baby frog or toad needs to breathe air directly. These complete changes can take 9 to 12 weeks.

This is metamorphosis!!!

 

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Here is a video of this transformation. It may be a little sophisticated. Your child may prefer animation, but give it a try. You can’t describe what metamorphosis is. Here a picture is worth a thousand words. https://www.youtube.com/watch?v=wAcwjWi6I9Y

Toads

 

As noted above, toads are in the same order as frogs (Anura), but some characteristics make them distinct. The first and most notable is their leathery and bumpy skin. Why the bumps, or why are they there? Remember that toads do not have to live close to the water when they are adults, but we all need water to survive. So, how might they have adapted? They carry their own purses of water or water-like liquid stored in those bumps on their skin. They can refill these sacs with water, by immersing themselves in a puddle after a rainstorm. The bumps may also serve as camouflage.

 

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There are some more differences between toads and frogs in the next section.

 
 

Compare and Contrast

If you have a collection of a series of photos or illustrations, or small toy frogs of different kinds, you can now invite your child to look for similarities or differences.  A quick photo montage may help: https://www.youtube.com/watch?v=oUBwBWC2oWQ

 

Frogs come in an amazing array of colors and patterns. Talk about how the frogs look similar or different.

 

 

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Does your child have a favorite? Draw and color these patterns. Make up your own colorful frog patterns or not so colorful. What purpose might these colors or patterns serve?

 

CAMOUFLAGE: Here in the US the skin on the backs of most frogs are colored and patterned for camouflage, so they blend into their surroundings. Their bellies are white. Why? Because if you are underwater and viewing them from below, say if you were a fish or turtle swimming below them or waiting on the bottom of a pond, the white would blend with the sky.

 

Many of the tropical frogs are brightly colored. This is common among poisonous frogs. What might those colors be communicating to predators? (Back off, because I am poisonous!!) Notice the differences in the colors.

 

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Not all frogs live in ponds. Some spend most of their time in trees. Can you find photos of tree-dwelling frogs? How have their bodies adapted to this environment? What is a tree frog’s camouflage? (Their colors range from green, gray or yellow.)

 

Some frog’s skin color changes with the temperature, others have the ability to change their skin color to match their surroundings (for camouflage), but unlike chameleons or an octopus, this ability is limited.

 

FROGS AND TOADS: What is the difference between a frog and a toad? Most folks get them confused, or just use one term for both groups. But there are important differences. Find photos or illustrations of frogs and toads. Compare and contrast noting the differences or similarities. Writing or drawing these differences can be helpful and encourage deeper observations and thinking.

 

Here are a few of the differences (but there are exceptions to these general rules):

FROGS:

  • Need to live near fresh water
    • Have smooth, moist skin
    • Have a narrow body
    • Have eyes that sit high on their heads and bulge out
    • Have long hind legs to take long high jumps
    • Have many predators (birds, fish, mammals, reptiles and even humans)
    • Have teeth

TOADS:

  • Do not need to live near water
    • Have dry and bumpy skin (not warts)
    • Have a wider body
    • Have eyes lower on their heads that do not bulge
    • Have shorter hind legs and they hop or run
    • Do not have many predators.
    • Have a gland (that can excrete a poison) behind its eyes.
    • Do not have teeth

Here is a good explanation of these differences, on Martha Stewart’s website of all places!

http://www.marthastewart.com/929675/differences-between-frogs-and-toads

MOVEMENT: Frogs and toads move differently. Examine these videos. Invite your child to imitate and role play first being a toad, and then a frog.

Frogs jumping: https://www.youtube.com/watch?v=yKpJElwama8

SOUNDS: Every different species of frog makes it’s own distinctive sound. They have a small sac, called a vocal sac, in their throats that vibrate the air as they slowly let it out. That is, air is pushed back and forth over the vocal cords in the sac to make a sound. A frog’s large mouth acts as a kind of amplifier, sending those sounds out over longer distances.

 

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Oh, and it’s almost always only the males who can make a sound. There could be different species of frogs croaking at the same time, but the females will recognize the call of their own species or a potential mate.

Listen Up!! These different frogs croaking are too funny. Great entertainment for a car ride.

https://www.youtube.com/watch?v=zhh6-Gy5THI

Listen to these frogs croaking; find the language to describe them. That is, what does it sound like or remind you of (a chirp, bark, grunt)? Can you copy it? Can you draw it (dots and lines, or something resembling musical notes)? Make up your own sound. That is, what would you sound like if you were a frog?

A frog will stop croaking if it sees something they think is a threat!

GENDER: How can you tell the difference between a male and female frog? The answer is by examining the size of their eardrum, which you will recall is behind their eyes. An eardrum smaller than the eye means the frog is female. So if the eardrum is the same size as the eye, that only leaves one other option, it’s a male!

 

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TONGUES: Compare a frog’s tongue with a human’s tongue. Frogs’ tongues are attached to the front of their mouths. Your tongue is attached to the back of your mouth. When a frog is after an insect, it throws its tongue out and wraps it around its prey. The tongue sits coiled in the frog’s mouth until it is sent flying out. The sticky tongue makes sure that the prey or catch stays on the tongue when it snaps back into the mouth.

 

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Frogs have teeth on the top jaw or the roof of the mouth that can also help to hold prey, but these teeth are too weak for chewing. Remember that frogs swallow their food whole with the help of the eyes that retract into their heads and push food down. We stick our tongues out, and while they are wet with saliva, our tongues could not be called sticky (unless you have just eaten some candy). Watch amazing videos and then draw or sketch a frog’s tongue.

https://www.youtube.com/watch?v=nwf0ahTYIOc

Not all frogs have tongues that catch prey in such a dramatic manner. Some just push or shovel food into their mouths with their front legs.

FOODS: A tadpole is a herbivore, living on algae or nibbling plants in the water. All adult frogs are primarily carnivores. So here is another interesting distinction between tadpoles and frogs, or food preference changes over the life cycle.

Another comparison is that adult frogs of different sizes will go after and eat different prey. Smaller frogs eat the smaller insects. Larger frogs eat larger insects such as grasshoppers and worms. The largest frogs will eat mice, small snakes, and even other frogs. Some frogs eat fruit.

 

COLD-BLOODED: Frogs are cold-blooded, meaning they cannot generate their own heat. What is the opposite? How do warm and cold-blooded animals differ? (A warm-blooded animal can create body heat, and a cold-blooded animal is essentially the same temperature as it is outside. Imagine if we could not make ourselves feel warmer!). A frog will bask in sunlight to warm itself up. Like many cold-blooded animals, it may need warmth to get moving.

BREATHING: As we described above, tadpoles have internal gills, and adult frogs have lungs. How would tadpoles breathe under water? How would adult frogs breathe if swimming (they would have to come to the surface to take a breath OR absorb through their skin what oxygen is in the water)?

When they are on land, a frog’s skin can become dehydrated. Their skin must remain moist so that they can continue to breathe through it. Their skin is a respiratory organ and helps control body temperature, so it needs to be protected. Some frogs are nocturnal so as not to spend too much time in the sun and risk water loss through evaporation.

 

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DRINKING: Frogs don’t drink water. Instead, they can absorb it through their skin. That is, their skin is permeable, allowing liquids and gas to pass through.

HIBERNATE: How do frogs spend winter? Some frogs burrow in mud or leaf litter just below the frost line and hibernate. That is, their heartbeat and breathing will slow and become almost undetectable (called torpor). Other frogs will go to the bottom of a deep lake and hibernate. Can you think of other animals who hibernate?

The bodies of some frogs produce a natural antifreeze (they store glucose in their liver), but some frogs can survive even after being frozen solid, or after becoming a “frogsicle”. When it warms up, these frozen frogs thaw coming slowly back to life.

An interesting fact is that for every year a frog hibernates, a ring forms on its bones. Thus, you can tell how old a frog is from studying the rings in its bones. This is not unlike telling the age of a tree from examining tree rings.

POISONS: Some frogs merely taste bad, but others are poisonous, producing chemicals. The Poison Dart frog produces a poison that was used on, you guessed it, poison darts or arrows that people used to hunt. American toads secrete a substance that is irritating to skin and membranes, particularly mucous membranes such as those in our noses. Dogs will froth at the mouth after chewing a toad. Some toads in the American Southwest can produce enough of this toxin to be fatal to dogs and other predators that happen to chew on them.

 
 

Measure

Frogs can jump 20 times their body length (or measurement from head to toe). One frog is said to jump 40 times its body length. What is your child’s favorite frog so far? How big is it typically? Examine that length on a ruler. Perhaps cut out a piece of cardboard of that length and then cut 20 more to see how far that frog can jump. You can also make these determinations on a tape measure, but the more hands-on activity of stacking a length end to end may make the point more effectively.

 

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Measure how far your child can jump. Now figure out a way to determine what 20 times that distance will be. You can create jumping units (cut out lengths), or a tape measure can show the distance and .

There are even frog-jumping competitions. The most famous is the annual Calaveras County Fair Frog Jumping Jubilee held annually at the Calaveras County Fair in honor of Mark Twain’s famous story on this topic published in 1867.

http://twain.lib.virginia.edu/projects/price/frog.htm

The current 3-jump record of 21 feet 5 ¾ inches has stood for 30 years.

 

Look at a ruler and figure out how small the smallest known frog is ( 0.4 – 0.5 inches). Look at how big the largest know frog is (12.6 inches).

http://www.wired.com/2010/08/tiny-frog/

https://en.wikipedia.org/wiki/Goliath_frog

 

 
 

Elaborate and Glossary

Just for fun:

  • A group of frogs is called an “army”?
    •A group of toads is called a “knot,” “knob,” “nest,” or “lump”.

Frogs absorb air and water through their skin. What does this mean for their health if their habitats are full of pollutants? Currently, there is a worldwide decline in the world’s frog populations. About one-third of the frog species globally is threatened with extinction. Since 1980, about 120 species have gone extinct. The permeability of their skin combined with living in water and on land makes them vulnerable to many environmental pollutants. The health of frogs is an important indicator of environmental stress. Have you considered a discussion of the risk to frogs of polluting? Make sure your child disposes of his trash properly and helps with recycling. These efforts may make it easier for the frogs to survive.

 

Frogs are an important part of the food chain. If you have not already discussed this topic, here is a chance to introduce a central tenant of ecology. Tadpoles consume algae, keeping water systems clear. Adult frogs consume vast quantities of insects, keeping those populations in check. And frogs are a food source for fish, snakes, birds, and several mammals, including monkeys. If the frog population declines, can it have a negative impact on the ecosystem? How? Discuss these problems, and why a food chain includes a reference to a chain (if you remove a link, the chain is compromised).

 

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Can you find examples frog fossils? The earliest true frog fossils are from the Jurassic period (or approximately 200 million years ago).

 

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Courtesy of the Exploratorium in San Francisco, CA, here is a list of links to a variety of websites having to do with all aspects of frogs and toads that you can explore with your children

 

http://www.exploratorium.edu/frogs/links.html

Lastly just for fun and a little departure from science – think of all the children’s cultural references in books, movies and even TV having to do with frogs or toads. Make a list and explore some of these treasures with your children. Here are a few to start your list.

  • The Princess and the Frog (Disney, 2009)
  • Toad of Toad Hall in Wind in the Willows (Kenneth Graham, 1908)
  • Kermit the frog from Sesame Street and the Muppet Show
  • Frog and Toad books by Arnold Lobel

 

 

Glossary

 

Frog

Toad

Tadpole/polliwog

Frogspawn

Metamorphosis

Permeable skin

Food web

 

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