The organisms in an ecosystem that first capture energy are called producers.

Here's why:

* Energy Flow: Energy flows through an ecosystem in a one-way direction, starting with the sun.

* Photosynthesis: Producers, mainly plants and algae, use sunlight, water, and carbon dioxide to create their own food through a process called photosynthesis. This process converts light energy into chemical energy stored in organic molecules (like sugars).

* Foundation of the Food Web: Producers form the base of the food web. All other organisms in the ecosystem depend on them, either directly (herbivores) or indirectly (carnivores and decomposers), for the energy they need to survive.

Examples of Producers:

* Plants: Trees, grasses, flowers, ferns

* Algae: Phytoplankton, seaweed

* Cyanobacteria: Blue-green algae