This is an organism that feeds on primary producers and make up the second tophic level

Plants and algae make their own food and are called (primary) producers. A few examples include grass and algae.

Herbivores eat plants and are called primary consumers. Something like a cow or deer.

Carnivores that eat herbivores are called secondary consumers. This includes animals like wolves, cougars, and humans.

a symbiotic relationship with the mitochondria