Tadpoles with crooked tails

[Geoff]

Does anyone know what could have caused this, and how I can stop it from happening to the others? How are the 2 affected tadpoles likely to develop?

It's always disappointing when something like this happens and I do sympathise with you. I experienced the same problem 16 years ago with X. borealis tadpoles. I cannot honestly remember what the eventual outcome was but I seem to think that some of the froglets had twisted spines. I bred the frogs again 8 years later expecting the same thing but on that occasion the problem I encountered was tadpoles with deformed forelimbs resembling "spindly leg syndrome" that breeders of poison dart frogs sometimes experience with their froglets.

I don't know what the cause is but I suspect that it might be related to a mineral deficiency in the water as I live in an area where the tap water is very soft (ie: low in Calcium and Magnesium). Below is a link to a paper about water hardness (GH), which concludes with "The common features of all the water sources evaluated that resulted in high survival and normal development of Xenopus embryos are a high concentration of calcium and a high GH value. Thus, we conclude that water hardness should be an important consideration in housing Xenopus females to be used for oocyte production." The article's a PDF document at: http://www.xenopus.com/Water_Hardness_final_proofs.pdf

[Gemma]

Thanks so much for the replies.

I didn't realise this was so common. I think 3 of the tadpoles might be like this but I'm not sure since they won't keep still, but at least 2 of them have bent tails. My affected tadpoles are about 2/3 through development too. It's a relief to know that in some cases they can develop normally. I'm praying they don't end up with twisted spines. Poor little things

Geoff, I hadn't thought about that as a possible cause. I don't have anything to test my water hardness with but I just found a website about water in my local area, put my postcode in and it told me that on average the water around here is very soft (10.8mg/l calcium, it said). I also suspect that it might be down to a mineral deficiency now. Thankfully most of the tadpoles seem fine and I have 10 seemingly healthy little froglets. I hope no more get affected.