Why is this tadpole still a tadpole (8 months later)?

[MikeTe]

My kids (10 and 12) caught this tadpole last June, as a little guy. As it got bigger, we figured it was a bullfrog tad.

Why hasn't it metamorphosed?

They've been taking good care of it..... obviously, I guess, b/c it has grown and it's still alive after all this time. They're quite experienced keepers now b/c of all the other frogs and toads that we have in the house. They change half the water every few days, feed it (and 2 big snails) turtle pellets and fish food every couple of days. It's 2.5 in. long and as active as a tadpole cares to be.

What's up?

Here's a pic from today:

[eric048]

whats the water temp, keep in mind some frogs take up to 3 years before they grow up

[SkeletalFrog]

Bullfrog time to metamorphosis depends on lattitude and temperature - in Florida, it can be as little at 6 months, but north it an be over 18 months.

[MikeTe]

The water was around 75 F last summer, early fall, but has been about 67 F this winter. I didn't realize that tadpoles would over-winter...... they all seem to disappear by the end of summer in the river. I've never, in my life, noticed a big bull-tad in the fall (they're generally hard to miss in the spring/summer, they're so big and fat).

...learn something new every day....

[SkeletalFrog]

The water was around 75 F last summer, early fall, but has been about 67 F this winter. I didn't realize that tadpoles would over-winter...... they all seem to disappear by the end of summer in the river. I've never, in my life, noticed a big bull-tad in the fall (they're generally hard to miss in the spring/summer, they're so big and fat).

...learn something new every day....

From what I know of the literature, bullfrog time to metamorphosis depends on frost-free time at a given site, and they often over-winter at high latitudes. Once it gets cold, they'll just sink to the bottom and go dormant until next spring.

However, I don't know how much plasticity there is in this - if you raise a Canadian bullfrog in Florida temperatures, will it metamorphose as quickly as a Florida bullfrog, or is the duration somehow genetically pre-set? I poked around and didn't find any papers on it, so it may be unknown.

[UncleChester]

Northern Green Frogs, Rana clamitans, will overwinter as tadpoles as well. They start reappearing in the early spring long before the adult versions have started calling.

I can't say I'd be able to distinguish one from a bullfrog at the tadpole stage though.

[KiwiSugar]

This can be normal depending on time of year, season, weather etc... He will be strong when does change

[Jimbok3]

I agree, here in VA bullfrog tadpoles take around two years to change (I have personally shortened the time, but it was through a high nutrient diet)