This is an example of a consumer.
All ecosystems are connected. From the top predator (the mountain lion) all the way to the smallest producer (grass). It is all connected. They are all connected by food chains and food webs. Food chains show how energy flows from one animal to another. All the food chains have everything linked together like a chain. Every part of a food chain is a living thing. A food chain is a way of showing what an animal eats to survive. Plants like grass and flowers are the first part of the food chain. Plants are the only nonliving thing in the food chain. They make their own energy so they are called producers. They use air, water and energy from the sun to produce there own food. The animals or consumers are the next part of the food chain. These animals can't make their own food. They must hunt for their food to get there energy. Herbivores, carnivores and omnivores are types of consumers. Herbivores eat only plants, carnivores only eat meat and omnivores eat both plants and meat.
Food chains can't always go in one direction. Sometimes they have to branch out like a web. Instead of calling this a food chain in different directions it's called a food web. A food web shows all the different kinds of food chains in an ecosystem and how they can overlap. For example, if there was a plant, rabbit, bird, ants and a lizard you couldn't put that in one strait line because the bird and the rabbit would eat the plant and the lizard would eat both the rabbit and the bird also, the bird would eat the ants too. Food webs can also show what kind of consumer an animal is. Here is how, the rabbit eats only the plant so it's a herbivore, the lizard is a carnivore because it eats the bird and the rabbit, the bird eats the ants and the plant so it's an omnivore.
Living things in a food web or food chain are all connected by the food they eat. There also should be a certain amount of different kinds of food. There should be more plants than anything because there are a lot of deer, rabbits, birds, lizards an other types of animals so if there are a bunch of those types of animals they have to have a lot of food for each one of them. There have to be a lot of plants for them to eat. So there are a lot of plants and a medium amount of deer, rabbits, birds, lizards etc. but where do the tiger, bear and shark go? Since they are top predators they go at the very top. Which is very narrow and thin so there are not many top predator animals. If there is not very much does that mean you can take them out? No, you can't because they eat the smaller animals that eat the plants so if predators were taken out of the food chain than the smaller animals would overpopulate and eat all the plants so the plants would then die because the animals that eat them ate all of the plants in the world so then they'd die of starvation. That explains why if you take out one group then the whole thing would die. So we need to make sure that you don't kill too many animals and don't get killed by an animal yourself.