The tadpoles are now frogs

About two weeks ago, as you may recall, Arlo and I collected a bunch of tadpoles from a vernal pool in Ypsilanti’s Riverside Park. Well, things seemed to be going pretty well for our amphibian friends up until yesterday…

Two days ago, things were awesome. We had about eight tadpoles that had sprouted back legs, and they seemed to be thoroughly enjoying life. They were eating the boiled lettuce that we were feeding them, and growing pretty quickly. When we went out yesterday morning, though, they were all gone. Our immediate thought was that they must have died, maybe because they weren’t getting enough oxygen in the tank where we were raising them, or, maybe, as Arlo suggested, because a predator of some kind had found them. While unlikely, we also thought that there might be a remote chance that they could have actually lost their tails and hopped from the tank over the 36 or so hours since we’d last checked up on them. [We had rocks coming up, out of the tank, so it’s conceivable that they could have climbed out.]

So, while we were almost positive that they’d died in captivity, we decided to go down to the park again, to check on the progress on the tadpoles that we’d left behind when we’d raptured away their little, green brothers and sisters. And, to our amazement, they were gone as well. While we were able to find about four or five tadpoles over the half hour we spent around the tiny — and quickly shrinking — pond, there was nowhere near the activity that we’d seen two weeks before, when there were literally thousands of tadpoles. But then we noticed something strange. The grass around the pond was full of tiny frogs, each about the size of a first grader’s pinky nail. And they seemed to be slowly moving in the direction of the Huron River. [Hopefully they make it before the lawnmowers return.]

Here are a few of the dozen or so that Arlo and I collected on Saturday morning.

While we still think it’s more likely that the tadpoles we took home with us met their end in the tank we were keeping in our backyard, at least there’s now a faint glimmer of hope that they evolved along the same timeline as the tadpoles in the park and just happily hopped away from captivity. For that to have been the case, though, they would have had to have completely lost their tails and transitioned into frogs between Thursday evening and Saturday morning. [When we last saw them, on Thursday evening, they’d just sprouted their hind legs.]

Here are two of the frogs Arlo and I had collected on Saturday morning, sitting on a lily pad in a pond behind the house in Canton where Linette grew up. [Arlo and I debated just carrying the frogs that we’d collected down to the river, but then decided that they might have a better chance in the backyard of Linette’s parents, where there aren’t either ducks or fish.] We dumped the frogs into the tiny pond, and they scattered, swimming quickly across the surface of the water. About half climbed up, into the plants surrounding the pond, and the rest found their way onto lily pads, like these two. Eventually, however, they too swam to the edges of the pond and made their way out.

update: OK, in spite of what we’d seen at the vernal pool, I’d been thinking there was no way that the frogs we saw in our backyard on Thursday evening, that had just sprouted their hind legs, could possibly have hopped away as fully-formed frogs by Saturday morning. Apparently, though, that makes perfect sense. I just looked up the frog development timeline, and I guess it’s a lot faster than I’d thought. From the sprouting of hindlimbs to complete metamorphosis, it just takes about 14 hours. Here are the highlights…

270 hours – development of hindlimbs, internal development of forelimbs in opercular cavity
275 hours – projection of forelimbs through operculum, left side first
280 hours – absorption of the tail and reduction in size of the gut
284 hours – metamorphosis complete, emergence from water as miniature, air breathing frog

If only we humans could absorb our tails that quickly.