Why doesn't our hands swell up due to osmosis , when we keep it in water for a long time ? ?

A cell wall is a permeable layer found in plant cells which acts as a membrane through which water molecules can pass through while animal cells do not have cell walls.. they just have a cell membrane which is selectively permeable to some chemicals or substances.. water does not move from the region of higher to lower concentration in animal cells

In short, plant cells have cell walls that allow osmosis while animal cells do not have cell walls for osmosis to take place

hope it helps you :)

Instead in our hands... something else happens rills or groove shaped lines are formed in our fingers.. it is an adaptation for our body to provide for some friction in water...

Spherical shaped cell might increase the surface area and decrease the volume.

Reduction in overall biodiversity