God created two great lights -- the greater light to rule the day and the lesser
light to rule the night. The source of light, the sun, spills over the horizon
each daybreak, shining its heat and light on the world below.
Every living thing needs energy to survive. It takes energy for you to jump, laugh, or
sing. Where does all that energy come from? It comes from the food that you eat! The lettuce
and tomatoes you eat in a salad were grown using water, soil, and the light and heat
energy from the sun.
A food chain follows the sequence of how the energy from the sun transfers from one living
thing to another. Every living thing belongs to a food chain. This simple food chain shows
the sequence of how the sun gives energy to the lettuce, and how that energy is then transferred
to the person who eats the lettuce.
Vast amounts of various plants cover the earth. Grass, sequoia trees, moss, and even seaweed
in the ocean, all harness energy from the sun and use it to create food through a chemical
process called photosynthesis. Plants that produce their own food are called producers
or autotrophs. All food chains start with autotrophs because they not only produce their
own food, but they also provide food for other animals.
Unlike plants, animals cannot produce their own food. They need to eat to have the energy
to run, move, and grow. Animals are referred to as consumers or heterotrophs because they
consume or eat food to get the energy they need. Let’s look back at our simple food
chain: The lettuce is a producer, or autotroph, and the person eating the lettuce is a consumer,
or heterotroph.
Now let’s examine another type of food chain. This food chain begins with a flower. A flower
is a producer or autotroph. Then a honeybee comes along and eats from the flower. The
honeybee is a consumer. Because the honeybee is the first consumer, it is called the primary
consumer. The honeybee uses the energy from the flower to move and grow. Now, the honeybee
is eaten by a skunk. The skunk is known as the secondary consumer because it is the second
animal to consume in the food chain. Animals who are secondary consumers are also known
as carnivores, animals that eat other animals. If a bear eats the skunk, the bear is known
as a tertiary consumer, or the third tier of consumer in the food chain. Our food chain
example ends here because bears are known as apex predators, which means they have no
natural predators and are at the top of their food chain.
One more important aspect of a food chain is what happens when a living thing dies.
Going back to our food chain example, eventually the bear will die. Scavengers such as Red
Weaver ants, vultures, or wild dogs help break down the material, and decomposers and detritivores
such as worms, maggots, flies, mushrooms, and bacteria will decompose the bear matter,
and ultimately, the nutrients will return to the soil. In the Bible we read, “for
dust thou art, and unto dust shalt thou return.” Producers will then use the nutrients from
this soil, along with water and the energy from the sun, to continue the cycle of the
food chain.
Because animals eat more than one type of food, it can get complicated to depict all
the food chains at one time. When we put one or more food chains together in a diagram
we can show the interconnection of animals and other living things, and how energy travels
from one thing to another. This is called a food web. A food web is a diagram that illustrates,
in a more sophisticated way, how food and energy transfer through an ecosystem. The
arrows on a food web indicate the direction in which energy is transferred. The heads
of the arrows point to the animal that does the eating, and the tails of the arrows show
what’s being eaten.
Countless varieties of plants and animals exist on the land and in the ocean, so numerous
food chains and food webs exist in each ecosystem. Let’s explore two different food webs and
the animals and plants found in each.
A wooded forest food web may contain grass, berries, robins, foxes, wolves, owls, squirrels,
mice, and more. Decomposers and detritivores might include earthworms, fungi, bacteria,
woodlice, and other organisms.
A marine food web may contain phytoplankton, seaweed, sea urchins, fish, sea otters, birds,
and decomposers and detritivores such as sea cucumbers, marine worms, mollusks, crabs,
and bacteria.
Both of these food webs depend upon the sun which allows producers to use energy from
the sun to produce food. This energy is transferred to consumers and then to decomposers and detritivores.
Food chains and food webs are a beautiful way to organize, envision, and describe God’s
grand design for each of his creations. Life on planet Earth thrives because the sun’s
energy is used by plants, animals, and decomposers to complete the cycle of life.