Carnivores, Omnivores, and Herbivores: Their Differences and Roles in the Food Chain

Animals of all sorts live together in various ecosystems. Within these natural communities, the animals eat specific diets that connect them together in a food chain. The three diets of animals include creatures that eat only plants, those that eat only meat, and animals that eat both plants and meat. Animals that eat plants exclusively are herbivores, and animals that eat only meat are carnivores. When animals eat both plants and meat, they are called omnivores. The balance of an ecosystem depends on the presence of every type of animal. If one type of animal becomes too numerous or scarce, the entire balance of the ecosystem will change.

Carnivores will feed on herbivores, omnivores, and other carnivores in an ecosystem. A natural community depends on the presence of carnivores to control the populations of other animals. Large carnivores include wolves and mountain lions. A large carnivore might hunt down large herbivores such as elk and deer. Medium-sized carnivores include hawks and snakes, and these animals typically feed on rodents, birds, eggs, frogs, and insects. Examples of small carnivores include some smaller birds and toads. These carnivores may eat insects and worms. Carnivorous animals have strong jaws and sharp teeth to enable them to tear and rip prey. These animals often have long, sharp claws that they also use to tear prey. Carnivores depend on sufficient prey in the food chain to give them the food they need. If the herbivore population or the population of other carnivores declines in an ecosystem, carnivores may not survive.

With a diet comprised of only plants, herbivores can be surprisingly large animals. Examples of large herbivores include cows, elk, and buffalo. These animals eat grass, tree bark, aquatic vegetation, and shrubby growth. Herbivores can also be medium-sized animals such as sheep and goats, which eat shrubby vegetation and grasses. Small herbivores include rabbits, chipmunks, squirrels, and mice. These animals eat grass, shrubs, seeds, and nuts. An ecosystem must provide abundant plants to sustain herbivores, and many of them spend the majority of their lives eating to stay alive. If plant availability declines, herbivores may not have enough to eat. This could cause a decline in herbivore numbers, which would also impact carnivores. Herbivores usually have special biological systems to digest a variety of different plants. Their teeth also have special designs that enable them to rip off the plants and then grind them up with flat molars.

Omnivores have an advantage in an ecosystem because their diet is the most diverse. These animals can vary their diet depending on the food that is most plentiful, sometimes eating plants and other times eating meat. Herbivores have different digestive systems than omnivores, so omnivores usually cannot eat all of the plants that an herbivore can. Generally, omnivores eat fruits and vegetables freely, but they can't eat grasses and some grains due to digestive limitations. Omnivores will also hunt both carnivores and herbivores for meat, including small mammals, reptiles, and insects. Large omnivores include bears and humans. Examples of medium-sized omnivores include raccoons and pigs. Small omnivores include some fish and insects such as flies. Omnivore teeth often resemble carnivore teeth because of the need for tearing meat. Omnivores also have flat molars for grinding up food.

Carnivores

• Carnivora Information
• What Is a Carnivore?
• Introduction to the Carnivora
• Insect Carnivores
• Carnivores, Conflict, and Conservation: Defining the Landscape of Conflict (PDF)
• Decline of Large Carnivores Creates Dire Environmental Ripple Effect
• Living With Large Carnivores
• Wildlife and Forestry Research: Carnivores
• Do Bigger Brains Make Smarter Carnivores?
• Large Carnivores, Moose, and Humans: A Changing Paradigm of Predator Management in the 21st Century (PDF)
• Carnivores, Herbivores, Omnivores?
• Forest Web Fast Facts (PDF)
• Ecosystems (PDF)

Omnivores

• What Is an Omnivore?
• Are Humans Omnivores?
• Omnivore Overview
• Carnivores/Omnivores of the Tundra
• Exploring Animal Diets and Sizes (PDF)
• Teeth Identification in Omnivores, Herbivores, and Carnivores
• Digestive Physiology (PDF)

Herbivores

• What Range Herbivores Eat and Why (PDF)
• Plants, Herbivores, and Predators
• Herbivory in Fish
• Global Decline of Large Herbivores May Lead to an "Empty Landscape"
• How Are Numbers Important?
• Large Herbivores Can Play Critical Role in Maintaining Ecosystem Health
• How Do Wild Herbivores Cope With Plant Toxins?
• Herbivores and the Dynamics of Communities and Ecosystems (PDF)
• Salt Marsh Herbivores
• Herbivores and the Number of Tree Species in Tropical Forests (PDF)
• Ingestion of Toxic Plants by Herbivores (PDF)
• New Study Suggests 60 Percent of Large Herbivores in Danger of Extinction
• Tundra Herbivores
• Effects of Herbivores on Grassland Plant Diversity (PDF)
• The Role of Insect Herbivores in Exotic Plant Invasions: Insights Using a Combination of Methods to Enhance or Reduce Herbivory (PDF)
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