iTutor Biology Updates

Hello everyone, I'm currently working on my masters thesis and everything is going great, except that I don't understand why it's not failing :roll: I'm working with marine flatworms (Schizorhynchia). During sampling, we gathered buckets of (wet) beach sand from which we extracted the worms with MgCl₂ anesthesia. My supervisor told me it's very important to use a solution with by and large the same concentration as the environmental conditions we encountered on the beach. This is because the worms are susceptible to osmotic disequilibria and will explode or shrink when exposed to too low or too high concentrations respectively. After identification, some worms were kept on alcohol (EtOH 99%) for DNA extraction and stored in the freezer. And here's what I don't understand; how come the animals don't swell and explode when exposed to nearly pure alcohol? Shouldn't the same rules apply as when we anesthetized them? I asked my supervisor about this and he told me the situation is different because the alcohol largely replaces the water in the worm's cells, but to be honest that doesn't make much sense to me. Even if that's the case, there is still a huge difference in solute concentration between the internal and external environment of the worm so I would still expect the worm to instantly swell and die. Today we checked some of the animals which were kept for DNA extraction and they looked just fine (which is great), but it would be nice to understand why this is the case. I hope someone can shed some light on this matter. Thanks in advance! Greets, Marlies