Help on Hypertonic and hypotonic with fish (1 Viewer)

[sixpaths97]

I dont understand if a salt water is a hypotonic or hypertonic. This goes the same for freshwater fish. Can someone please explain to me how a saltwater/freshwater fish is a hypotonic/hypertonic please.

Thanks :alone:

 

[Carrotsticks]

I dont understand if a salt water is a hypotonic or hypertonic. This goes the same for freshwater fish. Can someone please explain to me how a saltwater/freshwater fish is a hypotonic/hypertonic please.

Thanks :alone:

Hypotonic means that water goes IN the cells of the fish. This is because the cells of the fish have a higher solute concentration, so water tends to flow inside the cell to 'balance' out the concentration (via osmosis).

Hypertonic is the opposite. Water goes OUT of the cells of the fish.

So if I throw a freshwater fish into salt water, there's more solute in the external environment than in the actual fish. This means that all the water from the fish will flow OUT of it. A similar example is when you bathe yourself with some sort of bathwash for too long. Your fingers get wrinkly because all the water flowed OUT of your fingers and into the bath water.

If I throw a saltwater fish into fresh water, all the water will want to flow INTO the fish.

In general, water will flow to wherever has MORE solute (or salt in this case).

The 'tonicity' of the liquid is determined by how much solute there is with respect to the cells you're observing.

So in the case of a fresh water fish in salt water, the salt water is a HYPERTONIC solution, since there is more solute in the solution (salt water) than in the cells of the fish.

 

[sixpaths97]

Thank you!! This explanation was so much better than how my Biology teacher explains it.

 

[ipikip]

I dont understand if a salt water is a hypotonic or hypertonic. This goes the same for freshwater fish. Can someone please explain to me how a saltwater/freshwater fish is a hypotonic/hypertonic please.

Thanks :alone:

Mate. Salt water is hypertonic to fresh water. It contains more solutes (sodium chloride).

The concept of tonicity is a relative one. 'Hypertonic' means the solution you're talking about has more solutes than the solution you're referencing. 'Hypotonic' means the opposite, that the solution you're talking about has fewer solutes than the reference solution.

Regarding fish. The fluid in the cells of a salt water fish is hypertonic to fresh water (i.e., the concentration of water in the cells of the fish is less than the concentration in fresh water). Since things diffuse down their concentration gradient, if you put a salt water fish into fresh water, water moves into the tissues of the fish.