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Spring Issue




Frog Log!



Wow, sometimes I forget how long things have been going on at NatureNorth. This article was first posted in 1997. Now that it's been reformatted you can see some better versions of the original images, but we left the information the same. Frog-Log is still a good record of rearing Wood Frog tadpoles. Afterall, it's just the technology that has advanced, the frogs still do things the way they always have. And Sargent Park School is still rearing tadpoles every spring!

Watch Wood Frog eggs become froglets in this NatureNorth Critter Video!


Raising Wood Frog tadpoles is easy!

At Nature North, we practice what we preach. So we've been raising Wood Frog tadpoles, partly to show you how easy it is to do, but mainly because that's just what we like to do! Frog-Log is a record of the tadpoles we raised in 1997. We posted the progress of our tadpoles along with some pictures we took as they grew. It turned out to be a great record of the whole process, so we're leaving it up. If you're raising tadpoles, you can use this article as a reference guide. Just don't assume that your tadpoles will look the same at the same age as our's did. In nature, things do tend to vary!

We've also managed to get a number of Winnipeg Schools into the frog rearing spirit. At Sargent Park School , 13 class rooms (Nursery through Grade 4, the computer room, plus the Grade 8 math and Grade 7 Science rooms) raised wood frog tadpoles in 1998. There were 9 tanks full of tadpoles at Strathmillan School, 2 in Chapman School, 2 in Heritage School, 3 in Hedges School and 3 in Crestview School! Nature North supplied the tadpoles and rearing instructions, and the schools purchased small aquariums for each class room.

(Click links to see images!)


April 27
Manitoba Herps Atlas
Frog-Log 1997 began when we caught 4 adult wood frogs at a pond near the Winnipeg International Airport. Turns out we got 2 male and 2 female frogs. We put them in an indoor aquarium and the males spent the night calling!

April 28
By morning there were 2 pairs of frogs in amplexus - where the male grasps the female and holds on until she lays her eggs. By doing this the male is in the perfect position to fertilize the eggs as they are laid.

April 29
Both pairs were still in amplexus, no eggs yet.

April 30 [Eggs laid!]
The first female laid her eggs overnight and the second one laid her eggs around 11:00 a.m. The egg masses are about 5 cm wide. Each one contains about 500 eggs! Each egg is about 2 mm across, surrounded by a ball of clear jelly about 7 mm across.

May 1
The eggs are still just round black balls today. The temperature in the aquarium gets to about 22 C during the daytime when the aquarium light is on and drops to about 17 C overnight.

May 2
The eggs are changing rapidly, they are now clearly tadpole shaped blobs!

May 3 [Eggs hatch after 3 days.]
The eggs hatched today, most of them by late afternoon. The second batch was hatching about 6 hours behind the first, about the same delay as when they were layed! The tadpoles are about 8 mm long. Most of them are just hanging on the old egg mass or on the aquarium glass. They wriggle around once in a while.

We took the adults back to the pond where we got them and released them today.

May 4
The tadpoles are still just lying or hanging around. No sign of them feeding yet.

May 5 [Tadpoles = 2 days old.]
The tadpoles are about 10 mm long now. They are moving around a lot now, but still don't appear to have started feeding yet.

May 6
Took the tadpoles to Sargent Park School today, all 11 tanks with about 15-20 tadpoles in each. Transported them in a bag with all the stuff they'd need in the tank. Did a brief introduction for all the teachers and helped them get things set up.

May 9
The tadpoles are up to 13 mm long today. They've been munching actively since May 7. They're swimming around a lot now, they burst off when the tank is bumped. Our tadpoles are in a 15 gallon aquarium. Even so, we have begun to thin out the population by removing some tadpoles and placing them in a large plastic pool kept outdoors. With the cooler temperatures these tadpoles will develop at a slower rate.

May 12 [Tadpoles = 9 days old.]
The larger tadpoles are as much as 15 mm long. They are all actively swimming and eating well now, they shredded several lettuce leaves over the weekend. They are now able to control their buoyancy and can stay suspended in the water instead of sinking.

May 14
The tadpoles are up to 19 mm long. Some have been gulping air at the surface. Maybe this is part of how they maintain their buoyancy.

May 16
The larger tadpoles are now as much as 23 mm long. Their bodies are getting quite robust now, some are 6-7 mm wide. There are some tadpoles that are much smaller than the rest. Perhaps they are losing out in the competition for food. Thinned out the indoor tank again by removing about half the tadpoles again. There must have been about 1000 tadpoles hatched from the 2 batches of eggs we had. Now the outdoor pool is getting crowded! Might have to take some back to the pond.

May 20 [Tadpoles = 17 days old.]
The larger tadpoles are up to 28 mm long now! You can see their coiled guts quite well when you get a look at their undersides. I think there are the beginnings of hind limb buds appearing beneath the skin at the base of the tail.

May 23
The larger tadpoles are now 31 mm long. In this picture of the underside of a tadpole you can see various internal organs and other structures. The tiny rod-like structures extending out from the body at the base of the tail (left side of image) are hind limb buds. The well developed "beak" or horny jaws (right side of image) are for rasping away at food. In the center is the long coiled gut and the small round shape to the right of the gut is the heart. [This photograph was taken by gently squeezing the tadpole against the aquarium glass with another pane of glass. In this manner the internal organs of the tadpole are readily visible. I was able to watch the heart beating and the beak in operation.]

May 27
The tadpoles are as much as 35 mm long. Note the well developed mouth on this tadpole. Their eyes and the shape of their heads is starting to make them appear more "frog-like".

May 30 [Tadpoles = 27 days old, 30 days since eggs laid.]
These tadpoles just keep on growing! The biggest are up to 38 mm long. There is a lot of difference between the largest and smallest tadpoles in the aquarium, with the smallest being 1/2 the size of the largest. But the smallest ones are still larger than any of the tadpoles kept in the outdoor pool. The individual tail muscles are visible in a chevron-like design.

June 3
The tadpoles are really robust now. The largest is about 43 mm lg. The hind limbs are now clearly visible, though still small.

June 6 [Tadpoles = 34 days old]
The largest tadpole is about 50 mm lg. The hind limbs are growing rapidly now. No sign of fore limbs, though. Visited Sargent Park School today. Some of their tadpoles are ahead of mine! That's probably because the classrooms are warmer than the basement where my tadpoles are.

June 12
A 57 mm long tadpole dwarfs another from the outside pool. Cooler temperatures and more competition for food have resulted in this great size and developmental difference. Remember these tadpoles are both the same age!

June 16 [Tadpoles = 44 days old]
Things are really cookin' now! It's amazing how fast these guys go from being big tadpoles with legs to small frogs with tails. The first of mine have popped front legs. In the one pictured here you can see the bulge where its forelegs will soon push through. At Sargent Park School they've had some nearly complete their transformation! That's egg laid to frog in 47 days!

June 19 [Tadpoles = 47 days old]
All of my indoor guys are now froglets with tails. Today was the first day one of them crawled up onto the wooden island in the tank. It actually seems that the smaller tadpoles are transforming ahead of the larger ones; the first out of the water has a body length of only about 12 mm, not including tail. The longest any of them got to, as tadpoles, was about 60 mm. They're all shrinking now as they resorb their tales as food for their transformation.

June 23 [Froglets = 51 days old, 54 days from eggs laid to froglets!]
My indoor aquarium is full of froglets now! The largest have a body length of about 18-20 mm. They spend most of their time sitting on the little islands, but jump off into the water if I disturb them.

June 25 [Froglets = 53 days old]

Well, that's it for Frog-Log '97. My little froggies are going back to the wild today after some final posing. Sargent Park School held a special "frog release" at Bluestem Nature Park along Omand's Creek in Winnipeg yesterday (back in 1997!). Did you see us on CBC and CKND TV? We were the "happy-news" item at the end of the news casts! Thanks, Sargent Park School, for being a part of Frog-Log. Would your school like to try it out next year?

Thanks for checking out our Frog Log. Bye for now!

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