Life Cycle of a Frog

Chapter 19 ZoologyMs. K. Cox

http://allaboutfrogs.org/weird/weird.html

True Love? We will start with mating. When Frogs mate, the male frog

tends to clasp the female underneath in an embrace called amplexus. He literally climbs on her back, reaches his arms around her "waist", either just in front of the hind legs, just behind the front legs, or even around the head.

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True Love? We will start with mating. Amplexus can last several days! Usually, it occurs

in the water, though some species, like the bufos on the right mate on land or even in trees!(photo courtesy of Emile Vandecasteele)While in some cases, complicated courting behavior occurs before mating, many species of frogs are known for attempting to mate with anything that moves which isn't small enough to eat!


Spawn (egg-mass)

While in the amplexus position, the male frog fertilizes the eggs as they are laid. Frogs tend to lay single eggs in masses, whereas toads usually lay eggs in long chains. Some frogs leave after this point, but others stick around to watch over the little ones. Some have very unusual ways of caring for their young.


What do they look like?


Egg

Frogs and Toads tend to lay many many eggs because there are many hazards between fertilization and full grown frogness! Those eggs that die tend to turn white or opaque. The lucky ones that actually manage to hatch still start out on a journey of many perils.


Example: Some frogs, like the Coast foam-nest treefrog,

actually mate in treebranches overlooking static ponds and streams. Their egg masses form large cocoon-like foamy masses. The foam sometimes cakes dry in the sun, protecting the inside moisture. When the rain comes along, after developement of 7 to 9 days, the foam drips down, dropping tiny tadpoles into the river or pond below.


Frog Life Cycle 1. Amplexus 2. Life starts right as the central yolk splits in

two. It then divides into four, then eight, etc.- until it looks a bit like a raspberry inside a jello cup.

3. Shortly after hatching, the tadpole still feeds on the remaining yolk, which is actually in its gut! The tadpole at this point consists of poorly developed gills, a mouth, and a tail. It's really fragile at this point. They usually will stick themselves to floating weeds or grasses in the water using little sticky organs between its' mouth and belly area.


4. Then, 7 to 10 days after the tadpole has hatched, it will begin to swim around and feed on algae.5. After about 4 weeks, the gills start getting grown over by skin, until they eventually disappear. The tadpoles get teeny tiny teeth which help them grate food turning it into soupy oxygenated particles. They have long coiled guts that help them digest as much nutrients from their meager diets as possible.By the fourth week, tadpoles can actually be fairly social creatures. Some even interact and school like fish!


6. After about 6 to 9 weeks, little tiny legs start to sprout. The head becomes more distinct and the body elongates. By now the diet may grow to include larger items like dead insects and even plants.The arms will begin to bulge where they will eventually pop out, elbow first. 7. After about 9 weeks, the tadpole looks more like a teeny frog with a really long tail. It is now well on it's way to being almost fullgrown!


Young Frog, or Froglet

8. By 12 weeks, the tadpole has only a teeny tail stub and looks like a miniature version of the adult frog. Soon, it will leave the water, only to return again to laymore eggs and start the process all over again!

Goes with or in between 1 and 2. Usually, about 6-21 days (average!) after being fertilized, the egg will hatch. Most eggs are found in calm or static waters, to prevent getting too rumbled about in infancy!


9. By between 12 to 16 weeks, depending on water and food supply, the frog has completed the full growth cycle. Some frogs that live in higher altitudes or in colder places might take a whole winter to go through the tadpole stage...others may have unique development stages that vary from your "traditional" tadpole-in-the-water type life cycle: some of these are described later in this tour.Now these frogs will start the whole process again...finding mates and creating new froggies.


My, What Big Ears you Have! Frogs can hear using big round ears on the sides of their

head called a tympanum. Tympanum means drum. The size and distance between the ears depends on the wavelength and frequency of a male frogs call. On some frogs, the ear is very hard to see!

Ever wonder how frogs that can get so LOUD manage not to hurt their own ears? Some frogs make so much noise that they can be heard for miles! How do they keep from blowing out their own eardrums?Well, actually, frogs have special ears that are connected to their lungs. When they hear noises, not only does the eardrum vibrate, but the lung does too! Scientists think that this special pressure system is what keeps frogs from hurting themselves with their noisy calls!


Tympanum


Different purposes for feet Feet For Flying! Feet For Digging Feet For Swimming Feet For Climbing


What are these feet for?


Feet

What kind of feet are these?


What are these feet for?


What kind of feet are these?


I Only Have Eyes For You!

Frogs have variable kinds of eye types. The colored part of the eye is called the iris (EYE-riss). They can be brown, green, silver, red, bronze, and even gold. The pupils come in all kinds of shapes too!

(1) Round pupils: Some frogs have round pupils just like you and me. Newts and Salamanders also have round pupils.

(2) Vertical pupils: Vertical pupils that look like a cats eye are really good for night vision and respond quickly to changes in light.

(3) Horizontal-Shaped pupils: These are the more common pupil, good for normal day-vision.

(4) Heart-Shaped pupils: I'm not sure if it serves any purpose, but it sure looks neat! Oriental fire-bellied Toads have this type of pupil.

Some frogs have Triangular pupils, and some even have Star-Shaped pupils!


WHAT KIND OF EYES DO I HAVE?


B

D

A

C

WHAT KIND OF EYES DO I HAVE?


B Vertical pupils

D Heart-Shaped pupils

A Round pupils

C Horizontal-Shaped pupils

Lab Focus Today Hibernation: The frogs that live in colder climates

hibernate. Some dig holes or find cracks in logs or rock areas. Their heart beats and breathing slow down and their body temperature reaches close to the outside temperature. They have a lot of glucose in their bodies and it keeps them from freezing. Half-frozen frogs will thaw out and live. Some frogs hibernate under water. These don't breathe and get their oxygen from the water through their skin. (Cutaneous Respiration)


How to Tell if Your Tree Frog Is Male or Female It can be hard to tell if your pet frog is male

or female. Do some measuring. Males are noticeably

smaller than females in most species of frog. A typical male frog is one and one half to two and one quarter inches long from head to bottom. Females are two to three inches long.


How to Tell if Your Tree Frog Is Male or Female Be a good listener. Males croak at

night. This sounds like a duck quacking and sometimes a dog barking. Males will croak to the sound of vacuums, running water, loud noises, to attract females, and sometimes for no reason at all. Females, on the other hand, don't really make any noises.


How to Tell if Your Tree Frog Is Male or Female Understand that if you still can't figure it

out, you can ask an experienced breeder or a veterinarian.

Look at the throat. Most male frogs have a dark patch on their throat because as they croak it creates friction on the throat and darkens their throat.

Check the ear. The ear of the frog is near the brain. If its big, its a male but if it is small, then its a female.


Do Frogs Have Teeth?

Actually, yes! But not like in this silly picture!


Frog Teeth Most frogs do in fact have teeth of a sort.

They have a ridge of very small cone teeth around the upper edge of the jaw. These are called Maxillary Teeth.Frogs often also have what are called Vomerine Teeth on the roof of their mouth. They don't have anything that could be called teeth on their lower jaw, so they usually swallow their food whole. The so-called "teeth" are mainly used to hold the prey and keep it in place till they can get a good grip on it and squash their eyeballs down to swallow their meal.Toads, however, do NOT have any teeth.


Super Skin Frogs have very special skin! They don't just wear it, they

drink and breathe through it.

Frogs don't usually swallow water like we do. Instead they absorb most of the moisture they need through their skin. Not only that, but frogs also rely on getting extra oxygen (in addition to what they get from their lungs) from the water by absorbing it through their skin. Because frogs get oxygen through their skin when it's moist, they need to take care of their skin or they might suffocate. Sometimes you'll find frogs that are slimy. This is because the frog skin secretes a mucus that helps keep it moist. Even with the slimy skin, these frogs need to stay near water. Toads on the other hand have tougher skin that doesn't dry out as fast, so they can live farther from water than most frogs.


In addition to jumping in water, frogs and toads can get moisture from dew, or they can burrow underground into moist soil. Frogs shed their skin regularly to keep it healthy. Some frogs shed their skin weekly, others as often as every day! This looks pretty yucky...they start to twist and turn and act like they have the hiccups. They do this to stretch themselves out of their old skin! Finally, the frog pulls the skin off over it's head, like a sweater, and then (this is gross) the frog EATS IT!!!! (EEEEEWWW!)



How Long Do Frogs Live?

Amazingly, this is the hardest question I've been asked about frogs!

It turns out that very little is known at all about the natural lifespan of frogs. Partially, this is because it's pretty hard to track a frog all its life! (I guess they havent figured out a good way to put little tiny collars around their necks!)

However,some records show that in captivity, many species of frogs and toads can live for surprisingly long times. They seem generally average somewhere between 4 and 15 years!

Recently I ran across a page where people were posting data about how long their species of frogs had lived in captivity. The longest lifespan entered was a European Common Toad (Bufo bufo ssp.) at 40 years!!!!!


Other species which live to ripe old ages include:

Giant Toad (Bufo marinus): ranging between 7 and 24 years

Green And Black Poison Dart Frog (Dendrobates auratus): ranging between 7 and 17 years

Oriental Fire-bellied Toad (Bombina orientalis): ranging between 11 and 14 years

Ornate Horned Frog (Ceratophrys ornata) ranging from 5 to 12 years


examples of albino frogs.

This weird looking guy was found in a garden pond in the UK.Species: unknown.


Pac-Man Frog.

Here is the albino version of the same species, the Pac-Man frog.(Photo from the Best Buy Commercial from 1997, featuring this website!)


Horned Frogs Horned Frogs

(Ceratophrys), like this Gastrotheca ceratophrys have a projecting flap, or "horn," of skin above each eye. Click on the image to see it full sized.


Frogs and Myth

Lots of different cultures have all kinds of interesting myths pertaining to Frogs.

Frogs and Weather Frogs have been associated with weather in a lot of ancient cultures. I guess this really makes a lot of sense if you consider that they tend to make a lot of noise before rain storms.

Some Australian aborigines and Native American groups believed that frogs were the bringers of rain.

In India, frogs were believed to personify thunder in the sky. Even the word for "frog" also meant "cloud" in Sanskrit!

In China, they see the "TOAD", not the "man" of the moon. The toad is also considered "one of the five poisons of yin." They say that eclipses happen when the "toad in the moon" tries to swallow the moon itself!


Frogs and Luck Sometimes, cultures associated frogs with good and bad fortune.

In Japan, frogs are the symbols of Good Luck. One myth I read dealt with the idea that bullfrogs are descended from a great ancestor who could suck all the mosquitoes out of a whole room in a single breath!

Some myths are less favoring to frogs and toads. Some folklorists* have claimed that "If the first frog that you see in the spring is sitting on dry ground, it signifies that during the same year you will shed as many tears as the frog would require to swim away in."


If, on the other hand, the first frog of spring jumps into the water, you'll experience misfortune all year! However, if the springs' first "hoptoad" come jumping in your direction, you will have many friends; if it jumps away from you, you will lose some.

Some less enlightened people associate frogs, and Toads in particular, as evil incarnations of demons or devils!

Frogs and Warts Some say that you get warts from touching frogs and toads.


You get warts from human viruses, not from frogs and toads!Frogs have slimy skin to stay moist when it is dry, and toads have bumpy skin to help camouflage them in their habitat. Some frogs and toads have paratoidal glands which secrete poisons as protection which can cause skin irritations and may be poisonous to some species of animals, but warts have nothing at all to do with the frogs themselves!

The French and the Frogs For some reason, the French have been given the nickname Frogs...There are many different theories about how this came to be...


The story I had always heard was that the nickname dates waaay back to sometime around the 18th century, when Paris was surrounded by many swamps...The French nobility that would visit Versailles apparently tended to refer to Parisians as frogs because of the swampy surroundings...and only later did the term get picked up to describe the French in general.

Another story I've heard was that American soldiers adopted the nickname for the French during the World War II because they ate frog legs and hid well when camouflaged.

I've also heard that a frog used to be on the French Flag, before the Fleurs de Lis was adopted when King Clovis took the throne....


Batrachophobia- Fear of amphibians, such as frogs, newts, salamanders, etc.Ranidaphobia- Fear of frogs.Bufonophobia- Fear of toads.


End of Frog Section



Introduction These are amphibians and are of the order Caudata in

the scientific system of classification. The word "salamander" generally refers to any tailed amphibian lacking claws or ear openings. This means that newts are essentially salamanders. The definition of "newt" is a matter of great controversy and may vary from area to area or from country to country. Usually, the type of salamander known as a newt in many places is not as slimy as the majority of salamanders are, having rougher skin. Newts, unlike many other salamanders, may be semi-aquatic. Some people refer to salamanders that have a life stage known as the "eft" stage as newts. Again, however, such definitions may not hold true for everyone. For the purpose of this document, the word salamander will be used to indicate all types of salamanders including newts.


Housing

you should first determine what sort of habitat your animal is native to in the wild. Then, you should try to reconstruct this habitat as closely as possible. Most often this can be accomplished in a plastic or glass tank, as these are water impermeable.


Because salamanders can climb, aided with fluids or mucous secreted from their bodies, you should have a fitted lid for your enclosure. Salamanders often need such high levels of humidity, so a screen or mesh top may not be a good idea. Many people prefer to use a plastic lid with holes drilled into it.


Housing continued the tank has been set up and running for at

least a few days before your salamander arrives

Because salamanders are cold blooded and cannot produce their own heat, their temperature will essentially match that of their surroundings

Most salamanders, even terrestrial species, will require a high humidity. Generally this level is 50 percent or more.


Housing Continued These animals absorb water through their skins

rather than drinking it. Humidity may be increased and maintained in several ways. One way is to keep a bowl of water in the enclosure, although some people prefer to have a wet area of substrate rather than standing water.

Plants may also be used in the enclosure in order to help maintain humidity. These will allow shade to your animals in addition to collecting water droplets on their leaves. You may want to mist the enclosure several times a day as well


Housing Continued Most salamanders will appreciate a hiding

area in their enclosures. This can be created with leafy plants or with as simple an item as a cardboard box. This will provide it with a place to feel secure. Even aquatic salamanders will probably appreciate a floating plant that they can hide under. Many people like to place one hide box in each end of the enclosure. That way, the animal can thermoregulate without having to remain in the open.


Because amphibians have very sensitive skins, you should try to be extra careful to remove all chemical residue from the enclosure after cleaning.

There are two types of cleaners available for your use: mechanical and disinfectants


Housing continued Generally it is best to keep salamanders of the

same species together if you plan on having more than one salamander in each enclosure. Because salamanders may secrete toxic fluids, different species can actually be poisonous to one another. Also, salamanders may eat other salamanders, so cage mates should be roughly similar in size. Although some people choose to keep their aquatic salamanders with fish or aquatic frogs, this may cause the animals to be more susceptible to disease, and it may be difficult to keep them from eating the fish.


Diet

Most salamanders are carnivorous and feed on invertebrates, but nutrition requirements can vary from species to species.

Generally, terrestrial salamanders can be encouraged to feed by movement. Aquatic salamanders may be stimulated by odor, touch, and movement.


Diet continued Try to feed your animal a wide variety of

appropriate dietary items. This will not only keep it from developing an aversion to or "boredom" with the food, but it will help ensure that your salamander is getting a nutritionally balanced diet. Most salamanders will need to be fed a few times a week; however, younger salamanders may need to eat more often because they are growing.


Most salamanders will eat insects White worms, bloodworms, and

mealworms are all available for purchase and can be fed to your animal. Many people choose to use kingworms or superworms (Zophobas sp.), rather than mealworms.

Other insects including roaches, crickets, locusts, slugs, and flies are available for purchase as well. Some salamanders eat small feeder fish like guppies or goldfish, and others may eat pinkie mice.


Diet

Just make sure that the food items are fully thawed before they are offered to your salamander. If possible, warm the prey item up to the temperature it would have been when it was alive.



Pro-active care Salamanders shed their skin

every few days, every few weeks, or every few months. In colder temperatures, they may not shed at all, as their metabolism and body functions slow. If the level of humidity in the enclosure is appropriate for your salamander, there should generally be no problem with this process.


Pro-active care continued However, sometimes salamanders may

experience incomplete sheds, known as "dysecdysis". This means that some part of the animal's skin has been retained. As it dries, it can shrink, cutting off blood flow to the tissues underneath. If you notice that your salamander has retained some skin after its shed, it may be advisable to soak the area in tepid water before gently massaging it to remove the skin. If your salamander's skin is too delicate to handle, you should consult a veterinarian.


Health In order to select a healthy salamander, (signs that it may not be healthy) be sure that the

animal you pick is not bloated, or emaciated, (signs that it should be in good health) but it

should be plump. It should not have visible bones or inflammation on any part of its body. The skin should be clean and should not be discolored, cut, or scratched. The eyes of a healthy salamander are bright and clear, and there are generally no secretions around the eye, nostrils, or mouth areas. Healthy salamanders are usually active and will try to escape you if you attempt to pick one up


care Some salamanders have very fragile skins

and are not physically able to be handled. Their skins can be damaged by the oils in our skins, or by simple friction. Also, some salamanders can produce toxic secretions irritating to human skin.

After your salamander has been handled, be sure it has access to water or some other way to keep moist. Some species of salamander will let you know when they are stressed by arching their backs to show the bright warning colors of their bellies.


health

Some salamanders will naturally produce a protective slimy coating over their bodies and handling can disrupt this.

Some salamanders can regenerate limbs and tails if they lose them. However, this process is physically stressful for the animal and detrimental to its health.


Zoonoses are diseases that are transmissible from animals to humans. People that are most at risk are those who are immunocompromised or immunosuppressed, patients undergoing immunosuppressive therapies, infants and young children, the elderly, and those with a chronic disease that compromises the immune system.

Potential zoonotic risks: Aeromonas, Campylobacter, Citrobacter, Cryptosporidia, Enterobacter, Erysipelothrix, Klebsiella, Mycobacterium, Proteus, Pseudomonas, Salmonellosis, Serratia, and Yersinia enterocolitica.


health

The best way to avoid these and any other zoonoses is to maintain sanitary conditions and to wash your hands before and after handling your salamander. If you suspect that you may have acquired a zoonotic disease, you should certainly bring it to the attention of your physician.


Diseases Bumblefoot - inflammation of digits that can cause the

animal limitations in mobility or great discomfort. Physical Symptoms - swelling of the digits. In extreme

cases, the skin may split over the digit or the entire digit may drop off.

Cause/Transmission - bacterial infection. Stressed animals or animals in otherwise poor health or poor husbandry conditions may be more susceptible.

Treatment - bathe affected area in a bactericidal solution formulated for tropical fish. Usually three drops in a pint of water will resolve the infection if the animal is bathed twice a day for ten minutes in this solution. Consult your veterinarian.


Burns - skin damage caused by excessive heat. These may be general, covering the whole animal in extreme cases, but are more usually found localized over specific areas of an animal.

Physical Symptoms - visible damage to the skin, varying in extremity and ranging from areas of gray or red coloration to blistered areas.

Cause/Transmission - caused by direct heat touching the animal's skin. They may be occasionally caused by an exposed heating element in the animal's enclosure.

Treatment - for serious burns or burns covering a large area of your snake, consult your veterinarian. Less serious burns may be rinsed in a povidone iodine solution.


Dehydration - desiccation of amphibian. Physical Symptoms - dry, wrinkly skin,

emaciated look. Cause/Transmission - exposure to heat,

lack of water, low humidity. Treatment - soak or mist affected

amphibian to rehydrate. Keep amphibian clean to avoid opportunistic skin infections.


Dropsy - heavy accumulation of serous fluid in the amphibian's body.

Physical Symptoms - abnormalities or softening of abdominal skin; bloating.

Cause/Transmission - metabolic disruption or abnormality caused by poor husbandry and possibly bacterial infection.

Treatment - consult your veterinarian. Generally he or she will use a needle to aspirate the body fluid before disinfecting the resulting puncture wound.


Fungal infections - invasions of fungus over the animal's body, most often seen in aquatic animals.

Physical Symptoms - noticeable skin color changes, especially red or inflamed white tissues, ulceration of the skin. Slimy feel to skin, skin coated in fuzzy or creamy material or whitish threading.

Cause/Transmission - fungal spores or fungus in water, enclosure, or other amphibians or fish; dirty conditions; generally poor husbandry.

Treatment - consult your veterinarian


Internal Parasites - parasites inhabiting the host's internal organs. Varieties range from single celled parasites (such as Monocercomonas and Giardia) to worms (such as tapeworms).

Physical Symptoms - often there will be no symptoms although some animals may have decreased appetites, weight loss, or regurgitation. Subcutaneous parasites often can be felt just under the skin. Fecal or blood examinations by a veterinarian are the preferred methods of diagnosis.

Cause/Transmission - internal parasites are usually passed from one animal to another through direct and indirect contact between hosts which can include infected prey items.

Treatment - consult your veterinarian. Many will recommend medications such as Metronidazole, Oxfendazole, Fenbendazole, Levamisole, or Ivermectin.


Metabolic Bone Disease - most commonly seen in, but not limited to, herbivorous lizards, a calcium deficiency that causes the animal's bones to soften or break easily. In severe instances when the disease is untreated, paralysis or death may result.

Physical Symptoms - squeeze the animal's jaw gently. If it feels soft or if it "gives", the bones may have become soft. Lethargy or bent, collapsed backs may be another symptom. Most commonly, swellings on the limbs are evident.

Cause/Transmission - diets low in calcium or inability to process calcium due to insufficient sunlight/UVB exposure.

Treatment - ensure your animal is fed a proper diet and that it has plenty of exposure to sunlight. Consult your veterinarian if the condition continues to worsen.


Minor Cuts or Scrapes - minor skin damage caused by the abrasion away or slicing of the skin.

Physical symptoms - visible cuts or scrapes. Cause/Transmission - sharp surfaces in the

animal's enclosure which catch on the animal's skin, repeated contact with jagged or rough surfaces that has abraded the skin, physical skirmishes with other animals. Many times an animal will rub a part of its body, like its nose, repeatedly on a rough rock or screen and may abrade its skin. Live prey items can also scratch or bite your animal.

Treatment - clean the area with a povidone iodine solution. Consult your veterinarian.


Breeding The first step in breeding your salamanders

is to determine its sex. This may sometimes be done visually. Males of many species have forearms thicker than those of females. Some also have more streamlined bodies than females, and they may also be smaller. Sometimes the tails of males will be broader, or they may have larger hind legs.

Usually the cloaca of the male will be much more swollen or obvious than that of a female.


Breeding

Many salamanders can be encouraged to breed by a change in season. This may involve cooling then warming them to mimic the onset of spring, or you may have to aestivate your salamanders. Be sure to find out the specific requirements for your salamander in order to create a successful breeding situation.


Breeding Most salamanders have a rather different

breeding process than many other animals. Often, it consists of a courtship display in which the male will induce the female to mate. Sometimes this will involve moving her into an aquatic area. The male may display his tail or crest to her, or he may climb on top of her and grasp her in an embrace known as amplexus. When the female salamander gives a sign that she is ready, the male will usually produce one or more spermatophores, or sperm-containing clumps. Sometimes these are cone-shaped.


Breeding The female must then take up the

substance into her cloaca to fertilize her eggs. Sometimes she will do this independently, and sometimes the male will pull her across the spermatophores. Female salamanders may mate several times, and collect several spermatophores from different males. This is to ensure that her offspring are of varied genetic stock and that she will reproduce.


Breeding Although some salamanders might not show

pregnancy obviously, others can become quite plump. There are a variety of birthing methods among salamander species. Salamanders may lay eggs that hatch into larvae. The larvae then develop into adult salamanders. Some will give birth to living larvae. Others will produce eggs whose hatchlings have no larval stage, rather they emerge from their eggs as miniature adults. Many will lay eggs one by one, attaching them to some surface. Aquatic plants or rocks are commonly utilized for such a purpose.


Breeding

In the wild, young salamanders may be mistaken for tadpole frogs. It is usually best to separate any young salamanders from adult salamanders, as the mature animals may eat the babies. Babies should be fed the same food items as adults, but these items should be chopped small enough for the young amphibians to handle.


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Life Cycle of a Frog