Hello,

I am a beginner conducting experiments using Daphnia magna.

I've noticed that when female water fleas release eggs, sometimes they shed their exoskeleton and the eggs are released externally, and other times they hold the eggs inside their bodies until the young are able to swim, at which point the offspring push their way out of the mother's body.

In the case of the former, I heard that when eggs are released externally, the difference in osmotic pressure between the mother's body and the external medium affects the egg release.

It seems that in the case of Daphnia magna, the babies are released in the latter way, where they develop inside the mother's body until they are ready to swim.

In that case, doesn't the external medium enter the mother's body where the young are growing? From the images I've seen, it doesn't seem completely isolated from the outside, so I am curious.

I would appreciate any advice.....

Thank you