Here's why:

* Apicomplexa are characterized by a unique structure called an apical complex, which helps them penetrate host cells.

* All members of this group are parasitic, meaning they rely on a host organism for survival and reproduction.

* Some well-known examples of Apicomplexa parasites include:

* Plasmodium (causes malaria)

* Toxoplasma gondii (causes toxoplasmosis)

* Cryptosporidium (causes cryptosporidiosis)

Let me know if you have any other questions about protists!