Many people know that most frogs lay eggs, which then hatch into tadpoles that develop and metamorph into adult frogs over time. But how long does it take for tadpoles to turn into frogs?
In general, most tadpoles take anywhere from 6 weeks to as long as 8 months to turn into frogs depending on the species, availability of food, and environmental conditions. However, the tadpoles of some species, such as the Coastal-tailed frog can take up to 4 years to turn into frogs.
Tadpoles will typically develop faster in warmer temperatures, and slower in colder temperatures.
Other factors that affect tadpole development rate include the availability of food, and how crowded the pool is, among other factors.
Tadpoles in crowded pools will take longer to turn into frogs than those in less crowded pools (more information on that is below).
How Long the Tadpoles of 90 Frog Species Take To Turn Into Frogs
There are over 6,000 species of frogs around the world, found on every continent, except Antarctica.
Most of these frogs reproduce by laying eggs, which hatch into tadpoles that transform into adult frogs over time.
How long the tadpoles of a particular frog species take to turn into frogs can vary dramatically between species.
The tadpoles of some spadefoot toads can turn into frogs (toads) in as little as 2 weeks, while the tadpoles of the Coastal-tailed frog can take up to 4 years before they transform into frogs.
Below is a table that shows approximately how long the tadpoles of 30 frog species take to turn into frogs:
How Long Their Tadpoles Take to Turn Into Frogs
|Wood frog||Lithobates sylvaticus||65 – 130 days|
|Pickerel Frog||Lithobates palustris||60 – 90 days|
|Northern Leopard Frog||Lithobates pipiens||60 – 80 days|
|American bullfrog||Lithobates catesbeianus||1 – 3 years|
|Green frog||Rana clamitans||3 months – 1 year|
|Bronze frog||Lithobates clamitans clamitans||3 months – 2 years|
|African bullfrog||Pyxicephalus adspersus||17 – 35 days|
|Pacman frog||Ceratophrys||3 weeks – 2 months|
|Mink frog||Lithobates septentrionalis||1 – 2 years|
|River frog||Rana heckscheri||1 – 2 years|
|Crawfish frog||Lithobates areolatus||65 – 95 days|
|Pig Frog||Rana grylio||1 – 2 years|
|Coastal tailed frog||Ascaphus truei||1 – 4 years|
|Carpenter frog||Rana virgatipes||1 – 1.5 years|
|Gopher frog||Lithobates capito||87 – 225 days|
|Northern red-legged frog||Rana aurora||3 – 7 months|
|California red-legged frog||Rana draytonii||4 months – 1 year|
|Foothill yellow-legged frog||Rana boylii||3 – 4 months|
|Tarahumara frog||Rana tarahumarae||1 – 2 years|
|Cascades frog||Rana cascadae||2 – 3 months|
|Columbia spotted frog||Rana luteiventris||2 – 7 months|
|Oregon spotted frog||Rana pretiosa||3 – 4 months|
|European common frog||Rana temporaria||2 – 4 months|
|Mexican white-lipped frog||Leptodactylus fragilis||2 – 5 weeks|
|African clawed frog||Xenopus laevis||1 – 3 months|
|African dwarf frog||Hymenochirus||2 – 3 months|
|Tomato frog||Dyscophus||2 – 3 months|
|Florida bog frog||Lithobates okaloosae||1 – 1.5 years|
|Northern sheep frog||Hypopachus variolosus||3 – 4 weeks|
|Marsh frog||Pelophylax ridibundus||3 months – 1 year|
How Long Tree Frog Tadpoles Take To Turn Into Frogs
Below is a table that shows approximately how long the tadpoles of 30 tree frog species take to turn into frogs:
How Long Their Tadpoles Take to Turn Into Frogs (Approx.)
|Gray tree frog||Hyla versicolor||45 – 65 days|
|Cope’s gray tree frog||Hyla chrysoscelis||45 – 65 days|
|Spring peeper||Pseudacris crucifer||45 – 90 days|
|American green tree frog||Hyla cinerea||24 – 45 days|
|Cuban tree frog||Osteopilus septentrionalis||30 – 60 days|
|Pacific tree frog||Pseudacris regilla||2 – 3 months|
|Poison dart frogs||Dendrobatidae||2 – 3 months|
|Glass frog||Centrolenidae||4 months – 1 year|
|Red-eyed tree frog||Agalychnis callidryas||2 – 3 months|
|Amazon milk frog||Trachycephalus resinifictrix||1 – 2.5 months|
|Spotted chorus frog||Pseudacris clarkii||1 – 2 months|
|Pine woods tree frog||Hyla femoralis||2 – 3 months|
|Barking tree frog||Hyla gratiosa||2 – 5 months|
|Squirrel tree frog||Hyla squirella||1 – 2 months|
|Australian green tree frog||Litoria caerulea||1 – 2 months|
|European tree frog||Hyla arborea||2 – 3 months|
|Blanchard’s cricket frog||Acris blanchardi||2 – 3 months|
|Southern cricket Frog||Acris gryllus||3 -4 months|
|Northern cricket frog||Acris crepitans||1 – 3 months|
|Pine Barrens tree frog||Dryophytes andersonii||2 – 2.5 months|
|Canyon tree frog||Hyla arenicolor||1 – 2 months|
|Boreal chorus frog||Pseudacris maculata||2 – 3 months|
|Bird-voiced tree frog||Hyla avivoca||3 – 4 weeks|
|Arizona tree frog||Hyla wrightorum||2 – 3 months|
|Little grass frog||Pseudacris ocularis||2 – 2.5 months|
|Coronated tree frog||Anotheca spinosa||2 – 4.5 months|
|New Jersey chorus frog||Pseudacris kalmi||1 – 2 months|
|Mediterranean tree frog||Hyla meridionalis||2 – 3 months|
|Italian tree frog||Hyla intermedia||2 – 3 months|
|Iberian tree frog||Hyla molleri||2 – 3 months|
How Long Toad Tadpoles Take To Turn Into Toads
Below is a table that shows approximately how long the tadpoles of 30 toad species take to turn into toads:
How Long Their Tadpoles Take to Turn Into Frogs (Approx.)
|American toad||Anaxyrus americanus||1 .5 – 2.5 months|
|Fowler’s toad||Anaxyrus fowleri||1 .5 – 2 months|
|Western toad||Anaxyrus boreas||1 – 1.5 months|
|Cane toad||Rhinella marina||3 weeks – 6 months|
|Great Plains toad||Anaxyrus cognatus||1.5 – 2 months|
|Canadian toad||Anaxyrus hemiophrys||1.5 – 2 months|
|European toad||Bufo bufo||2 – 3 months|
|Natterjack toad||Epidalea calamita||1.5 – 2 months|
|Arizona toad||Anaxyrus microscaphus||2 – 3 months|
|Southern toad||Anaxyrus terrestris||1 – 2 months|
|Colorado River toad||Incilius alvarius||3 – 4 weeks|
|African common toad||Sclerophrys regularis||2 – 5 months|
|Mexican burrowing toad||Rhinophrynus dorsalis||1 – 3 months|
|Oriental fire-bellied toad||Bombina orientalis||2 – 5 months|
|Wyoming toad||Anaxyrus baxteri||1 – 2 months|
|Eastern spadefoot toad||Scaphiopus holbrookii||1 – 2 months|
|Western spadefoot toad||Spea hammondii||1 – 2.5 months|
|North American green toad||Anaxyrus debilis||2 – 4 weeks|
|Red-spotted toad||Anaxyrus punctatus||1.5 – 2 months|
|Houston toad||Anaxyrus houstonensis||2 weeks – 3 months|
|Eastern narrow-mouthed toad||Gastrophryne carolinensis||3 weeks – 2.5 months|
|Yosemite toad||Anaxyrus canorus||1 – 2 months|
|Woodhouse’s toad||Anaxyrus woodhousii||1 – 2 months|
|Oak toad||Anaxyrus quercicus||1.5 – 2 months|
|Arroyo toad||Anaxyrus californicus||2 – 3 months|
|Sonoran green toad||Anaxyrus retiformis||2 – 3 wees|
|Great Plains narrow-mouthed toad||Gastrophryne olivacea||1 – 2 months|
|Coastal plains toad||Incilius nebulifer||3 – 4 weeks|
|Great Basin Spadefoot||Spea intermontana||1 – 2 months|
|New Mexico spadefoot toad||Spea multiplicata||2 weeks – 1.5 months|
Stages of Development: From Tadpole to a Frog
1. Hatchling Tadpole
The first few days after hatching, tadpoles won’t have the energy to swim yet. They will feed on the remaining yolk of the eggs. This will provide them with enough energy to grow and develop further.
2. Swimming Tadpole
After a few days, the tadpoles are strong enough to swim around and will start feeding on food sources available in the water.
At this early stage, tadpoles have long coiled intestines that are specially designed to digest plant matter. They will only eat algae, plankton, and the soft roots of aquatic plants such as duckweed.
3. Toothed Tadpole
After about 4 – 6 weeks (can vary depending on species), the tadpoles grow teeth, and their intestinal tract will gradually shorten, allowing the tadpoles to eat animal matter.
Apart from plant matter, they also start to eat animal matter, such as small insects that fall into the water.
4. Tadpole With Legs
At about 6 weeks old, the tadpoles will start to grow legs, starting with the back legs. At this point, their gills are also covered by a special pocket of skin called an ‘operculum’ and become internal gills.
5. Froglet Stage
At 12 – 14 weeks old, the tadpoles have developed fully developed legs, and their lungs are getting larger. After their legs have developed, they become stronger and more refined.
Tadpoles at this stage look like tiny frogs with tails and will spend a lot of their time by the edge of the water, sometimes leaving the water.
Froglets cannot survive out of water for a long time, so they will return to their pond frequently at this stage.
6. Young Frog
At about 14 – 16 weeks, the tail is lost, and the legs are more refined. Once metamorphosis fully is complete, the tadpoles are now young frogs.
These frogs will leave the water, for life a land.
Temperature Affects How Long Tadpole Development Takes
Tadpoles that hatch in early spring, when the weather is colder, usually take longer to develop – and those that hatch later when the weather is warmer will typically develop faster.
This is because temperature affects development rates.
In general, tadpoles and other amphibian larvae will develop faster in warmer temperatures and slower in colder temperatures.
Amphibians are ectothermic (cold-blooded) which means their body temperature varies with surrounding environmental temperature. As the temperature changes, so does their metabolism.
For tadpoles to develop normally and metamorph into froglets, the surrounding water temperature should stay within a certain range.
If the temperatures fall beyond their preferred range, their metabolism and development rate will decrease – and if the temperatures drop too low, tadpoles can completely stop developing.
On the opposite end, if the temperatures rise above the preferred range, the tadpoles can have trouble getting enough oxygen from the water which can lead to a very high mortality rate.
This is because metabolism and tadpole activity increase with temperature, but at the same time, the amount of dissolved oxygen decreases with temperature.
In addition, in warmer temperatures, tadpoles will divert more of their energy towards maintaining adequate oxygen levels, rather than development. This can lead to a decreased rate of development.
Sometimes, Tadpoles Can Deliberately Delay Their Development Due to Cold Weather
Many frogs have extended breeding seasons, and some tadpoles hatch from their eggs late in the year.
When this happens, the tadpoles may choose to overwinter in the pond and finish their development the following spring.
Adult frogs hibernate during the winter. Their metabolism slows down, and they stop eating; instead using up energy reserves they created throughout the year.
However, newly metamorphosed frogs wouldn’t survive the winter as they have not gotten themselves ready for hibernation yet. So, some tadpoles may choose to put off metamorphosis until the following spring.
They will continue to swim and feed during the winter, provided it is not too severe.
If water temperatures near the surface of the pond get too low, the tadpoles can swim to deeper water where the water is warmer.
In this way, the tadpoles of some species, such as the American bullfrog can delay metamorphosis by up to 2 years – overwintering twice at the bottom of ponds.
There are advantages to delaying metamorphosis:
- Tadpoles that wait a long time before becoming frogs can grow bigger by the time they change. Their larger size makes them well-equipped to find food and defend themselves.
- Tadpoles that live through winter can become frogs early in the following spring. This gives them a head start over that season’s tadpoles in competing for resources.
- Tadpoles may have a better chance of surviving the winter than adult frogs. This is because they are better suited at surviving low oxygen conditions, which is helpful as pond surfaces can freeze during winter.
When a pond freezes over, the layer of ice blocks air from the water’s surface, and there are no currents to mix oxygen into the water. Tadpoles have a higher surface area to volume ratio and can breathe through their skin more efficiently than most adult frogs.
Although overwintering frogs require less oxygen than they normally do, low oxygen conditions can still be fatal to them.
Since frozen ponds have lower oxygen levels, many frogs overwintering in frozen ponds do not survive the winter. This is known as “winterkill.”
Other Factors That Affect Tadpole Development Rate
The tadpoles of some frog species grow and develop faster than others. For example, frogs that breed in temporal pools (such as spadefoot toads) that dry up in the summer, will have higher growth rates. This allows them to escape their ponds before the water dries up.
However, frogs that breed in permanent ponds (such as the American bullfrog) are in no rush to leave the water and can afford to develop at much slower rates.
2. Food Availability
Diet is an important factor that influences tadpoles’ development, and ultimately metamorphosis.
In a lab experiment, tadpoles raised on a high-quality diet grew faster and transformed into frogs quicker than tadpoles raised on a low-quality diet.
In another experiment, tadpoles starved early in development delayed metamorphosis by 8%, and those starved midway in their development took 19% longer to undergo metamorphosis.
When tadpoles are in crowded pools, they develop slower and will take longer to go through metamorphosis. Tadpoles in crowded pools have been found to develop slower even with a high availability of food.
In one experiment, a researcher raised tadpoles in different volumes of water. He found that crowding has little effect on the rate of tadpole development during the first 2 weeks. But later development greatly affected – decreasing rapidly in crowded conditions.
It was also found that the tadpoles that grew to the greatest body size went through metamorphosis earlier than tadpoles that remained small.
In addition, another experiment found that tadpoles developed slower when raised in water previously crowded by other larger tadpoles.
4. Environmental Cues
Tadpole development rate can be influenced by various environmental cues. For instance, tadpoles in drying pools have been found to respond by metamorphosing more quickly.
However, the newly metamorphosed frogs will be smaller than those from slower-drying pools.
Some Tadpoles Can Morph and Develop Faster
Some tadpoles, such as those of spadefoot toads are polymorphic: meaning they can develop in more than one form.
Normally, spadefoot tadpoles are omnivores that have jaw muscles and mouthparts that are proportioned when compared to the rest of the body. These are called ‘omnivore morphs.’
Despite being the same age as ‘normal’ spadefoot toad tadpoles, carnivore-morph tadpoles are larger, and have bigger, broader heads, a slimmer body, and smaller guts.
They also have keratinized mouthparts that are bigger and have serrated edges, with a dorsal hook.
These two morphs behave differently: omnivore-morph tadpoles gather in schools, while carnivore-morph tadpoles are solitary.
Canivore-morph spadefoot tadpoles tend to develop more quickly than their ‘normal’ counterparts, due to their high-protein diet.
Most Tadpoles Never Get To Turn Into Frogs
The tadpole stage is the most vulnerable stage of most frogs’ and toads’ lives. Frogs often lay eggs in temporary pools of water, and sometimes, these pools dry up before the tadpoles have had enough time to metamorph into adults.
In addition, tadpoles are also preyed on by fish, adult frogs and toads, salamanders, newts, birds, snakes and other reptiles, many mammals, and even predatory insects such as water boatmen and dragonfly larvae.
For these reasons, it’s common for over 90% of tadpoles in a pond to be wiped out before they can undergo metamorphosis and transform into adult frogs.
Frequently Asked Questions:
When Do Tadpoles Leave the Water?
Tadpoles leave the water when they reach the froglet stage, which is about 12 – 16 weeks in many species. At this point, the tadpole’s gills have disappeared, its lungs have grown larger, and its limbs have completely developed.
Newly transformed froglets look like tiny frogs with tadpoles tails. A few weeks later, the tail is lost and metamorphosis is complete.
How Can You Tell How Old a Tadpole Is?
The best way to guess how old a tadpole is – is by looking at its stage of development. Generally, If a tadpole is not yet swimming or eating, it’s at least less than 4 days old. If a tadpole has full gills, and no legs, it’s most likely less than 4 weeks old.
If a tadpole has teeth and is omnivorous (can eat animal matter), it is at least 6 weeks old – and If a tadpole has well-developed legs, and looks like a tiny frog with a tail, it is at least 12 weeks old.
It’s important to note that these figures are rough estimations and are not set in stone. The tadpole development rate can vary between species. Also, there are many factors that make a tadpole grow faster or slower than is normal for that species (mentioned above).
How Long Does It Take for Tadpoles to Hatch?
Tadpoles can take anywhere from 12 hours to as long as 6 weeks to hatch depending on the species, and environmental temperature. Tadpoles will develop and hatch faster at warmer temperatures, and slower are colder temperatures.
What Month Do Tadpoles Turn Into Frogs?
In the Northern Hemisphere, the tadpoles of most frogs that lay eggs in early spring will start turning into frogs by late April to early May. However, some tadpoles can turn into frogs by June or July, or even as late as September.
Photo credit: the1pony (CC BY-ND 2.0).