I recently collected some spadefoot toad tadpoles eggs and put them in my pond. Now I am curious if the tadpoles would mature faster if they thought the water was going to evaporate soon. Last week I moved some of them to a shallower container just to see if they all mature at the same time. Does anyone have any direct knowledge on this.
We raised a couple of golden tree frogs from tadpoles. Aside from putting in fresh water every few days we didn’t do anything different over the course of their development. Eventually they just lost their tails and started climbing the walls. Both of them went through the various stages within a couple of days of each other.
Interestingly, some time after they became froglets, one started growing much faster than the other, to the extent that we eventually separated them because we were afraid the smaller one might get hurt or even eaten. We don’t know why that happened–they are both evidently male, since they vocalize. They are both still around and the smaller one did grow more, but never caught up with his brother in size,
What were you saying about their triggers?
I was wondering if a pond drying up might trigger faster development. It seems mine are growing slower than some of the wild ones but it might just be my imagination. I was expecting about 6 weeks till they grew legs, mine are 4 weeks now and still very small.
I lived near a small creek in a forest for a few years. The creek had running water in winters if it rained a lot, but dried up in the spring. It was full of tadpoles, and when the creek began to dry up, they all started turning into frogs. I can’t say for sure if correlation was causation here, since I didn’t do any controlled experiments. But I got that impression, though.
Strangely, the vast majority of the frogs disappeared very quickly. I get that only a minute percent of them will live to be full-sized adults. But I expected that the zillions of little frogs would mostly be around for a while, disappearing gradually over some time as they failed to thrive or get eaten or otherwise didn’t survive. But no, the vast majority of them disappeared within just a few days.
The toads will disperse very quickly and continue to travel as long as they can stay hydrated, tree frogs like to be near water more than todas but will also disperse fairly quickly. If the survival rate were only 1 in 100 we would soon be over run.
This is only speculation, but I wonder if the speed of development would be affected by water temperature. That seems more likely than the depth of the water to affect metamorphosis.
For a system to work in which metamorphosis is triggered by evaporation would require the parent frogs to know how to select bodies of water that will evaporate at just the right point in the tadpoles development. And what would be the benefit of that? Frogs aren’t my area, but I believe it’s simple timing. I wouldn’t be surprised if there were some external inputs nudging it a bit here and there, but I doubt they would be a very large factor.
I allready know they will become frogs in a certain amount of time. I was curious if there were any conditions that might trigger a quicker development. Usually once a pond starts to dry up the tad poles become overcrowded in the remaining puddles. I do know that regional populations have evolved to develop quicker than others, such as in the desert where they are lucky to have a pool for 1 month. Come to think of it these particular tadpoles were harvested in the desert.
That was my initial guess, as well.
HoneyBadger, I do know that different species turn from tadpoles into leggy adults at different rates. That could influence your experience and observations.
I know that different species do as well, I also have some greenfrog tadpoles which will take several months, bullfrogs may take a couple of seasons. The spadefoot toad specificaly is what I am reffereing to in this post. A rain pond may have upward of 100,000 tadpoles in a season. If only 1,000 survive because the pond dried up I imagine those 1,000 would carry a gene for quicker development.
I think I will try some experiemnts but I may have trouble duplicatiing the overcrowding which I suspect could be one of the triggers if in fact a trigger mechanism does exist.
There was a documentary about exactly this the other day (on BBC4) - the development of tadpoles is indeed influenced by a variety of factors, including availability of food, concentration of salts and oxygen in the water, temperature, etc, and also by the stage of development of other tadpoles - in some cases, development would be retarded by months and the tadpoles would overwinter in the water and emerge in spring.
Concentration of salts makes good sense as the concentration would increase as the water evaporated. I could not find any studies on this in particular but did see mention of salts in how well they thrived.