Crested newt - neoteny question

[Jennewt]

I have a batch of T. karelini that have finished morphing 3-4 weeks ago. However, there is one that is still a larva and shows no signs of morphing. It is just as big as the others, but still has full-sized gills and the full broad tail-fin of a larva. Is this one just a late bloomer, or are there known to be neotenics among populations of this species?

 

[john]

Larvae don't necessarily metamorphose at the same age and size - there is a lot of variation in most genera. Apart from the obvious variations in genetics, there is also the possible environmental influence, the general thinking of which is that if food is abundant in the water, what's the rush to metamorphose?

As far as I'm aware, neoteny can occur in most Triturus species, though I think it's less common in the large bodied Triturus species.

I bet your remaining larva will transform in a few weeks time.

 

[nimbus2]

I raised 70 Triturus boscai larvae last year, and all but 13 of them metamorphosed within a few weeks of each other. The 13 remaining (who were identical in age and size to the others) did not begin to metamorphose until 6-7 months later. So as John mentions, I bet yours will morph in time.

 

[Jennewt]

Yep, you two were right. It's morphing, about 6 weeks later than the others.