What is at the bottom of a marine food chain?

These microscopic, single-celled algae are primary producers, meaning they can create their own food through photosynthesis. They use sunlight, water, and nutrients to produce energy, forming the foundation of the marine ecosystem.

Here's why phytoplankton are so important:

* Energy source: They provide the initial energy that fuels the entire marine food web.

* Oxygen production: Like plants on land, phytoplankton produce oxygen through photosynthesis, contributing significantly to the Earth's atmosphere.

* Base of the food chain: Zooplankton, small fish, and other marine animals feed on phytoplankton, and these animals are in turn eaten by larger predators.

So, without phytoplankton, the entire marine ecosystem would collapse.