Daphnia - incomplete molt?

[Brandt]

I started a daphnia magna culture 3 months ago, and it's been doing very well. However, I recently noticed something that makes me wonder it there's some sort of deficiency in my culture. Some of the larger (older) daphnia are not completing their molt entirely. That is, the molted carapace is still attached near the tail, and drags behind them as they swim. Any ideas what's causing this? Thanks!

 

[SludgeMunkey]

I started a daphnia magna culture 3 months ago, and it's been doing very well. However, I recently noticed something that makes me wonder it there's some sort of deficiency in my culture. Some of the larger (older) daphnia are not completing their molt entirely. That is, the molted carapace is still attached near the tail, and drags behind them as they swim. Any ideas what's causing this? Thanks!

Perfectly normal daphnia behavior.

May want to throw a small handful of oyster shell, or lime stone in. Even better, a ground up Calcium supplement tablet. Older cultures tend to quickly use up the dissolved carbonates in the water. I find a little extra carbonate hardness in the water goes a long way with long term daphnia culture.

 

[Brandt]

Perfectly normal daphnia behavior.

May want to throw a small handful of oyster shell, or lime stone in. Even better, a ground up Calcium supplement tablet. Older cultures tend to quickly use up the dissolved carbonates in the water. I find a little extra carbonate hardness in the water goes a long way with long term daphnia culture.

Very helpful (and reassuring). Thanks!