• An omnivore is an organism that regularly consumes a variety of material, including plants, animals, algae, and fungi. They range in size from tiny insects like ants to large creatures—like people.

    Human beings are omnivores. People eat plants, such as vegetables and fruits. We eat animals, cooked as meat or used for products like milk or eggs. We eat fungi such as mushrooms. We also eat algae, in the form of edible seaweeds such as nori, which are used to wrap sushi rolls, and sea lettuce, eaten in salads. Bears are omnivores, too. They eat plants like berries as well as mushroom fungi and animals like salmon or deer.

    Omnivores are a major part of the food web, a description of which organisms eat which other organisms in the wild. Organisms in the food web are grouped into trophic, or nutritional, levels. There are three trophic levels. Autotrophs, organisms that produce their own food, are the first trophic level. These include plants and algae. Herbivores, organisms that consume plants and other autotrophs, are the second trophic level. Both omnivores and carnivores, meat eaters, are the third trophic level.

    Autotrophs are called producers, because they produce their own food. Herbivores, carnivores, and omnivores are consumers. Herbivores are primary consumers. Carnivores and omnivores are secondary consumers.

    Most birds are omnivores. Robins pull worms from the ground. They also feast on berries. Ostriches graze on plants and grasses. They also eat lizards and insects.

    Many mammals are omnivorous. Skunks eat rodents, lizards, honeybees, leaves, grasses, nuts, fungi, and almost anything else they can find.

    Some reptiles are also omnivorous. Box turtles feed on fish, frogs, rodents, and many other creatures, but they also eat flowers, berries, and roots.

    Fish can also be omnivorous. The opaleye, a fish that feeds mostly on seaweeds along the Pacific Coast of North America, also eats small creatures found among the seaweed.

    Some insects are omnivores. Ants eat seeds, nectar, and, often, other insects.

    Some omnivores are scavengers, creatures that eat the meat of dead animals. Black bears eat mostly nuts, berries, and other fruit. But if they find a dead animal, they eat it.

    Many animals that are often thought of as carnivores are in fact omnivores. Red foxes, for example, prey on rabbits, but they also eat fruit.

    Some animals that are thought of as herbivores also eat animals. Squirrels eat mostly nuts, fruits, and seeds, but they sometimes eat insects, small birds, and other creatures.

    Omnivore Adaptations

    Many omnivores have biological adaptations that help them eat a variety of kinds of foods. They have adapted many characteristics of both carnivores and herbivores. Like many carnivores, raccoons have sharp front teeth that help them rip apart mice and other small creatures. And like many herbivores, raccoons also have large molars that help them chew up plants. Raccoons also have quick paws and long fingers that they can use both to grab prey and to reach a variety of fruits and other plant products.

    Compared to herbivores and carnivores, omnivores often have a greater chance of surviving difficult conditions. They can adjust their diets. If all the salmon or other animals disappear from a river ecosystem, a big cat living in that habitat could not survive. Cats are carnivores that cannot digest or obtain nutrients from plant material. However, a grizzly bear could still survive eating berries, fruit, roots, and insects.

    Because they have an easier time finding food, omnivores are sometimes better at adapting to new environments than creatures with more specific feeding habits. Omnivores can better adapt to development than herbivores or carnivores.

    Urban development, the process of clearing land for homes, business, and agriculture, destroys habitats, the places where animals live in the wild. Herbivores such as elephants cannot survive without a lot of trees and grasses to eat. But omnivores such as opossums, seagulls, and many species of monkey easily adapt to life in urban areas and farmland, where they often find meals in garbage cans.

    Omnivores can often adapt well to changes in their habitat by adjusting their diet.

    Living Garbage Cans
    Some animals, such as tiger sharks or goats, have been known to consume a wide variety of objects: aluminum cans, surfboards, clothes and textiles, plastics, and rope. These "living garbage cans" are not considered omnivores, because they gain no nutritional value or energy from these products. Tiger sharks are carnivores that mistake these items for food. Goats are herbivores that are curious about unique odors or new foods.

  • Term Part of Speech Definition Encyclopedic Entry
    agriculture Noun

    the art and science of cultivating the land for growing crops (farming) or raising livestock (ranching).

    Encyclopedic Entry: agriculture
    algae Plural Noun

    (singular: alga) diverse group of aquatic organisms, the largest of which are seaweeds.

    autotroph Noun

    organism that can produce its own food and nutrients from chemicals in the atmosphere, usually through photosynthesis or chemosynthesis.

    Encyclopedic Entry: autotroph
    big cat Noun

    large predators, including tigers, lions, jaguars, and leopards.

    biological adaptation Noun

    physical change in an organism that results over time in reaction to its environment.

    box turtle Noun

    small reptile with a tall, domed shell.

    carnivore Noun

    organism that eats meat.

    Encyclopedic Entry: carnivore
    characteristic Noun

    physical, cultural, or psychological feature of an organism, place, or object.

    consumer Noun

    person who uses a good or service.

    decline Verb

    to reduce or go down in number.

    development Noun

    growth, or changing from one condition to another.

    Encyclopedic Entry: development
    diet Noun

    foods eaten by a specific group of people or other organisms.

    Encyclopedic Entry: diet
    digest Verb

    to convert food into nutrients that can be absorbed.

    ecosystem Noun

    community and interactions of living and nonliving things in an area.

    Encyclopedic Entry: ecosystem
    farmland Noun

    area used for agriculture.

    food chain Noun

    group of organisms linked in order of the food they eat, from producers to consumers, and from prey, predators, scavengers, and decomposers.

    Encyclopedic Entry: food chain
    food web Noun

    all related food chains in an ecosystem. Also called a food cycle.

    Encyclopedic Entry: food web
    fruit Noun

    edible part of a plant that grows from a flower.

    fungi Plural Noun

    (singular: fungus) organisms that survive by decomposing and absorbing nutrients in organic material such as soil or dead organisms.

    grizzly bear Noun

    large mammal native to North America.

    habitat Noun

    environment where an organism lives throughout the year or for shorter periods of time.

    Encyclopedic Entry: habitat
    herbivore Noun

    organism that eats mainly plants and other producers.

    Encyclopedic Entry: herbivore
    insect Noun

    type of animal that breathes air and has a body divided into three segments, with six legs and usually wings.

    mammal Noun

    animal with hair that gives birth to live offspring. Female mammals produce milk to feed their offspring.

    meat Noun

    animal flesh eaten as food.

    molar Noun

    large, flat tooth used for chewing and grinding.

    monkey Noun

    mammal considered to be highly intelligent, with four limbs and, usually, a tail.

    mushroom Noun

    fungus, usually with an umbrella-shaped cap on top of a slender stalk.

    nectar Noun

    sweet plant material that attracts pollinators.

    nori Noun

    red algae that is often dried and used to wrap sushi.

    nutrient Noun

    substance an organism needs for energy, growth, and life.

    Encyclopedic Entry: nutrient
    omnivore Noun

    organism that eats a variety of organisms, including plants, animals, and fungi.

    Encyclopedic Entry: omnivore
    opaleye Noun

    medium-sized fish native to the Pacific Ocean.

    organism Noun

    living or once-living thing.

    ostrich Noun

    very large, flightless bird native to Africa.

    plant Noun

    organism that produces its own food through photosynthesis and whose cells have walls.

    prey Noun

    animal that is hunted and eaten by other animals.

    primary consumer Noun

    organism that eats plants or other autotrophs.

    producer Noun

    organism on the food chain that can produce its own energy and nutrients. Also called an autotroph.

    reptile Noun

    animal that breathes air and usually has scales.

    robin Noun

    small bird native to Europe.

    rodent Noun

    order of mammals often characterized by long teeth for gnawing and nibbling.

    root Noun

    part of a plant that secures it in the soil, obtains water and nutrients, and often stores food made by leaves.

    scavenger Noun

    organism that eats dead or rotting biomass, such as animal flesh or plant material.

    Encyclopedic Entry: scavenger
    sea lettuce Noun

    seaweed with large, flat leaves.

    seaweed Noun

    marine algae. Seaweed can be composed of brown, green, or red algae, as well as "blue-green algae," which is actually bacteria.

    secondary consumer Noun

    organism that eats meat.

    specific Adjective

    exact or precise.

    sushi Noun

    bite-sized rolls or balls of sticky rice topped with seafood or vegetables.

    tamarin Noun

    small monkey native to Central and South America.

    trophic level Noun

    one of three positions on the food chain: autotrophs (first), herbivores (second), and carnivores and omnivores (third).

    urban area Noun

    developed, densely populated area where most inhabitants have nonagricultural jobs.

    Encyclopedic Entry: urban area
    vegetable Noun

    plant that is grown or harvested for food.