A food chain always begins with a producer. Food is made by this organism. Since plants can make their food through photosynthesis, most food chains begin with green plants. A living thing that eats other plants and animals is called a consumer.
There are many kinds of autotrophs, but plants are the most familiar. Seaweed, which is a larger form of algae, is autotrophic. Additionally, phytoplankton, which lives in the ocean, is an autotroph. There are some types of bacteria that are autotrophs. As an example, bacteria living in active volcanoes produce their own food from sulfur compounds. Chemosynthesis is the name given to this process.
The second trophic level consists of organisms that eat the producers. These are called primary consumers, or herbivores. Deer, turtles, and many types of birds are herbivores. Secondary consumers eat the herbivores. Tertiary consumers eat the secondary consumers. There may be more levels of consumers before a chain finally reaches its top predator. Top predators, also called apex predators, eat other consumers.
Consumers can be carnivores (animals that eat other animals) or omnivores (animals that eat both plants and animals). Omnivores, like people, consume many types of foods. People eat plants, such as vegetables and fruits. We also eat animals and animal products, such as meat, milk, and eggs. We eat fungi, such as mushrooms.
Sources that are used: National Geographic societies