Do you have a child who loves frogs and other amphibians? Hatching frog or toad eggs is a great STEM science project for budding herpetologists. It is such a fun and inexpensive family project, and so exciting to watch the amazing frog life cycle metamorphosis from frogspawn to tadpole to froglet!
We always smile, thinking about how much fun it was to hatch frog and toad eggs as kids.
It’s more than a science project. Kids learn much more, like patience, responsibility, attention to detail, and gently caring for fragile creatures.
We’re tempted to try this again. All of these photos are from our froglet adventures.
There’s not much needed to get started, and not as complicated as you might think.
Before you begin
First, check your local laws on collecting and releasing local non-endangered frogspawn, as it varies from location to location.
Please do not purchase frog eggs from suppliers or online, as there is a high risk of introducing potentially damaging invasive species to your local ecosystem.
Once hatched, froglets should be returned exactly where you found them. Moving frogs between different ponds increases the risk of spreading a disease or invasive non-native plants.
One batch of eggs may contain hundreds of frogspawn, so please respect their little lives and don’t collect more than you can properly care for.
How fancy the setup is up to you. Go frugal, or create a set-up to last for other adventures.
I had four aquariums growing up and countless bug jars…our poor mother.
Container: Clear containers are best for observation. Larger containers will be less work, as more diligence is needed to keep the water clean and oxygenated in smaller or overcrowded ones. If you use something from home, make sure nothing toxic was stored in it before. A longer, rectangular shape is better than a tall and narrow one.
Container Option 2: Great for an all-included package, options like this 10-gallon are good, especially if you want to make a small investment that can be reused for other hobbies and pets. Set the included filter to the lowest setting possible and add a sponge like this to the suction part of the filter so the tiny tadpoles don’t get sucked into it!
Oxygen: Air pump with a small airstone. Tadpoles don’t like agitated water, just a gentle bubbling. TIP: a large filter is unnecessary unless you’re very careful with the choice, as they can suck up the tadpoles and create too much current.
Rocks & Plants: Place a couple of large rocks, pond weeds, java moss, or duckweed (available at aquarium stores) in the tank. Eventually, you will need to build a slope with rocks, gravel, or pond mud when the tadpoles start becoming froglets (see “Metamorphosis Begins”)
Water: The best is to collect extra pond water while collecting eggs. Using pond water will bring home good bacteria to keep your tadpoles happy, and you don’t have to worry about chlorine. If you need to top it up with tap water, it’s VERY IMPORTANT to let the tap water sit for THREE days before using it to let the chlorine evaporate or use Seachem Prime water conditioner – a few drops remove chlorine, chloramine, detoxifies ammonia and nitrate.
Frog Metamorphosis Diary
A notebook or camera for a kid’s frog life cycle diary. We do have a separate article about age-appropriate cameras for children if you’re curious (See Photography for Kids)
This is my terrifically geeky detailed frog life cycle drawn around age 10.
Choose a location indoors or outdoors that is bright and gets some sun to allow algae to develop. The tadpoles will eat algae, which also helps to purify the water and increase oxygen levels.
But be careful if the spot gets a lot of sunshine. Monitor the temperature so that it reaches no more than 27°C/80°F. You don’t want crispy fried tadpoles.
Housing outdoors will allow rainwater and mosquito larvae for the tadpoles to eat. Just make sure it doesn’t freeze!
A secure lid with air holes will be needed to prevent birds and cats from eating the frog eggs and then, as they start becoming froglets, to prevent them from climbing out themselves.
Keeping about 5-10 tadpoles per liter of water is a good idea. You can keep more, but they may die out faster or become carnivorous (so one cluster of frog eggs per large container).
Important: NEVER clean the container or anything you put into it with soap, detergent, vinegar, or any other cleaning solutions. Only use water! Anything else is toxic to the little ones.
When to collect Frogs Eggs?
This varies depending on the species and the climate where you live.
In colder climates here in Canada, you can listen to frog and toad calls starting in late March. Further North, where it’s colder, this delays into April-May. Spring peepers and wood frogs are typically earlier, but larger frogs like bullfrogs may call late, such as June-July.
Your local area may have a nifty list to get you excited about what species are near your home, and you may even have some frog calls for you to listen to! Listen carefully, and you might be able to discover which frog species you’re collecting.
For example, Frog Watch
Supplies for collecting
- Rubber boots (or hip waders)
- Net or scoop
- Rain gear, just in case!
- One bucket for eggs (at least 1L to allow enough oxygen for the trip home and to keep the water from getting warm too quickly)
- One larger bucket to bring home extra pond water (this is important to bring good bacteria into the home set-up)
- If it’s a long trip home or if you like a warm car, consider a cooler to keep the frogspawn from getting too hot (and maybe use buckets with lids for the bumps along the road)
- Camera to take some snaps of the fun
Where to collect
Early evening is usually the best time to try and listen for frog choruses, though early in the season, this can even be mid-day. Look in small streams, creeks, ditches, ponds, or depressions in fields or forests. Scan for areas with dead grass, weeds, or vegetation like cattails, as the dark masses of eggs are often deposited there. Just listen and look!
how to collect
It’s best to scoop frog egg clusters directly into a container.
Or, if using a net, scoop the frogspawn gently and draw them towards you without lifting the frog eggs from the water, then put them in the container.
Use sharp scissors if you need to split up a large batch of frog eggs (cut the clusters through the jelly, avoiding the eggs). The individual frog eggs are surrounded by hard jelly and attached together into a mass with softer jelly. Gently cut the soft gel part and avoid the eggs themselves. You won’t need to do this if you take the whole batch.
Fill an extra bucket with pond water and take it home for the home set-up.
If you expect a long trip home or like the heater at full blast, pop them in the cooler and keep away from the heat vents.
keeping it clean
It’s important to keep the water clean and oxygenated.
Bacteria and lack of circulation can quickly use up all the oxygen, and the tadpoles will suffocate. This can happen overnight!
If the water goes cloudy, smells foul, or tadpoles are lingering near the surface, exchange part of the water (up to 30% at a time, once every 6 hours or so) until it’s clear again.
Be sure that the new water is close to the same temperature as the water already in the tank – drastic changes in water temperature can kill your tadpoles.
And remember: Using more pond water is best. Avoid using chlorinated water, but if you need to, let it stand for a few days first to allow the chlorine to evaporate, then mix it with some rainwater. Or, as mentioned in the supplies list, you can use a water conditioner like what is used in aquariums.
TIP: See the note about using a turkey baster or gravel cleaner in the supplies list
- Lettuce, romaine, or green leaf only. Boil for a few minutes until soft and squishy, cut into smaller pieces, and let them float in the water. Do not use cabbage or iceberg lettuce.
- Occasionally supplement the lettuce with slices of cucumber, pre-soaked in non-chlorinated water.
- A few pond leaves with algae on them.
- They’ll also eat algae in the tank and any pond critters that hitched a ride every time you added fresh pond water.
Be careful not to overfeed. Feed only what the tadpoles can eat in an hour to avoid fouling the water. Remove any uneaten food within the hour. Too much food can cause death to the tadpoles from overeating.
Tadpoles don’t actively feed for the first 3-5 days, as they will rely on the protein from their egg yolks when they hatch. When they start swimming around, it’s time to start feeding.
Do not feed the tadpoles when they have sprouted arms. The tadpole will be using its tail as food, becoming an adult frog (see below “metamorphosis begins”).
Tiny hind legs appear after 20-30 days from hatching (at room temperature).
40-60 days from hatching, the tadpoles are fully grown and ready to transform. They will stop eating. Transformation becomes much more rapid at this point. Fat little tadpoles with legs will become tiny froglets with shrunken tails in 5-7 days.
This “land” area should be against the edge of the tank, not in the middle, as some frog or toad species will only look along the edge for a place to emerge, swimming until they become exhausted and drown. Ensure your tank has a secure lid, as wet froglets and toadlets can climb glass.
Keep that in mind, but don’t panic when it gets cold; the tadpoles will grow more slowly in winter. The ideal temperature is between 20°-25°C / 68°-77°F.
The timely release of tadpoles is critical. When your tadpoles begin to come out of the water to breathe, it’s a signal that they have metamorphosed from vegetarian to carnivore. As soon as they completely lose their tails, it’s time to quickly release your froglet or toadlets.
Enjoy the thrill of seeing them swim away home!
More Science Ideas!
How to Hatch Praying Mantis Egg Cases
For another fun STEM science project, see how we hatch praying mantis eggs!
We enjoy doing this every year – it is so fun!
The Big Sis