Here's why:

* Animal cells use flagella for movement. Think of sperm cells, which use a flagellum to propel themselves towards the egg.

* Plant cells don't typically move around, so they don't need flagella. They have cell walls that provide structure and support, and they rely on other mechanisms for movement (like cytoplasmic streaming).

While flagella are generally associated with animal cells, there are a few exceptions:

* Some single-celled organisms (like protists) have flagella, even though they aren't technically animal cells.

* There are a few rare instances where plant cells might have flagella, but these are very unusual.

Overall, the presence of flagella is a key characteristic that distinguishes animal cells from plant cells.