Here's why:

* Producers are organisms that make their own food through photosynthesis.

* Phytoplankton are tiny, single-celled algae that live in the ocean.

* They use sunlight, carbon dioxide, and water to create their own food, just like plants on land.

Phytoplankton are incredibly important to the ocean ecosystem because they form the base of the food web, providing food for a wide range of marine organisms.