M. alpestris metamorphosis?

[simon]

I have a bunch of M.a. apuanus larvae. They all hatched in January and most of them are growing well.

Temperature: 17-19 degrees C. Diet: newly hatched brine shrimps, Daphnia magna and white worms.

One of them is, to me, showing signs of metamorphosis such as shrinking of the gills. It is one of the bigger ones, but is not more than 29 mm in total length.
It says here Caudata Culture Species Entry - Mesotriton (Triturus) alpestris that they metamorphose between 4-6 month old, and of course it has not yet metamorphosed. But it looks like it’s about to (Most of them look like the pic in the bottom left, while this one has even smaller gills than the mid-metamorphosis pic taken by Tim Johnson).
I simply thought they would be bigger when they metamorphose.
So my questions are how big are yours usually when they metamorphose and how old are they then.

/Simon

 

[Azhael]

Size at metamorphosis is greatly influenced by housing conditions and diet. The richer and more abundant the diet is, the bigger they´ll morph.
This species can morph at a tiny size , though, so it´s not abnormal. White worms are a rather poor fodder and larvae grown on them don´t do that well. Try changing them for tiny earthworms, you´ll have much better results.
Also, colder temps and deep water are usually factors that lengthen the larval period, thus leading to a bigger size at morphing.

Best of lucks! they are gorgeous and fascinating little fellas

 

[Jennewt]

Two months and 29 mm does seem too young and small to be morphing. Be sure you have a secure lid on the tank, just to be on the safe side. In addition to food, crowding can also be a factor in timing of metamorphosis. How many do you have, and in what size container?

 

[simon]

The white worms have been a rather small portion of the diet.
I wish I could get hold of tiny earth worms but Sweden is still a winter wonder land

However, I have kept them at rather crowded conditions with low water level (about 40 larvae in 40*40 cm with 3 cm water level), so that might very well play a role. I underestimated the size a bit though. It's more like 31 mm.

I'm going to divide them in two groups after size and move the ones looking like they are about to metamorphose to a secure container.

 

[Jennewt]

Why only 3 cm of water? Larvae can be in deep water. Even if you are doing 100% water changes, I would still have deeper water than that.

 

[ajc]

Hi Simon, sounds like I'm a granddad again.
Mine lay in April and morph in September, temperatures around 70-75F over the summer, as much food as they can eat.

 

[simon]

Yes, the animals I got from you are top quality! I really enjoy them.

Basically their crowded conditions depend on that I live in a very small flat with my wife and loads of frogs and some newts. Because I gave the 40 larvae such little space I wanted to make sure the water is properly oxygenated (as much surface per litre), hence the low water level. But I might have been too stingy with the water. I will rise it a bit, especially now when I divide the group (less larvae per litre).

Now it has moved on to land. Such a stunning little version of the adults!