Here's why:

* Isotonic: In an isotonic solution, the concentration of solutes outside the cell is equal to the concentration of solutes inside the cell. This means there's no net movement of water across the cell membrane, and the cell maintains its normal shape and volume.

* Hypotonic: In a hypotonic solution, the concentration of solutes outside the cell is lower than inside the cell. This causes water to move into the cell, potentially causing it to swell and burst (lyse).

* Hypertonic: In a hypertonic solution, the concentration of solutes outside the cell is higher than inside the cell. This causes water to move out of the cell, leading to shrinking and potentially crenation (shriveling).

In summary:

* An isotonic environment is ideal for animal cells as it prevents excessive water movement in or out of the cell, maintaining its structure and function.

Let me know if you'd like more details on any of these osmotic environments!