Here's why:

* Symbiosis: This term describes any close and long-term interaction between two different biological species.

* Parasitism: This is a specific type of symbiotic relationship where one organism (the parasite) benefits at the expense of the other (the host).

While parasitism is often seen as a negative interaction, it is still a form of symbiosis because it involves a close and persistent relationship between two species.

Key points to remember:

* Not all symbiotic relationships are parasitic. Other types include mutualism (both species benefit) and commensalism (one species benefits, the other is unaffected).

* Parasitism can have a significant impact on host populations.

Let me know if you have any other questions about symbiosis or parasitism!