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

[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.

[Jimbok3]

can you post a bigger pic and a closeup pic of the tadpole?

if you can than i should be able to distinguish what type it is......

[MikeTe]