More information Feeding relationships are often shown as
simple food chains in reality, these relationships are much more
complex, and the term food web more accurately shows the links
between producers, consumers and decomposers. A food web diagram
illustrates what eats what in a particular habitat. Pictures
represent the organisms that make up the food web, and their
feeding relationships are typically shown with arrows. The arrows
represent the transfer of energy and always point from the organism
being eaten to the one that is doing the eating. Trophic leves
Organisms in food webs are commonly divided into trophic levels.
These levels can be illustrated in a trophic pyramid where
organisms are grouped by the role they play in the food web. For
example, the 1st level forms the base of the pyramid and is made up
of producers. The 2nd level is made up of herbivorous consumers and
so on. On average, only 10% of the energy from an organism is
transferred to its consumer. The rest is lost as waste, movement
energy, heat energy and so on. As a result, each trophic level
supports a smaller number of organisms in other words, it has less
biomass. This means that a top-level consumer, such as a shark, is
supported by millions of primary producers from the base of the
food web or trophic pyramid.
Slide 7
Sea life interesting facts All living things depend on each
other to live. The food chain shows how some animals eat other
animals to survive. While being food for animals higher in the food
chain, these animals may eat other animals or plants to survive.
The food chain is a complex balance of life. If one animals source
of food disappears, such as from over fishing or hunting, many
other animals in the food chain are impacted and may die. Let's
look at two examples of food chains, one in the water and the other
on land. In the Sea All sea creatures rely on other sea creatures
for food to survive. At the bottom of the food chain are the sea
plants and plankton. Many types of fish and animals such as the
snail, shrimp, jellyfish, and sea star eat the plankton.
Slide 8
Part 2 interesting facts Sea Plants Sea Snail Little Fish The
small animals and fish who eat plankton then become food for larger
fish, such as the tuna and mackeral. These fish are then eaten by
larger fish and animals, such as the shark and dolphin. And who
eats the shark? Check out the menu at a seafood restaurant next
time you are eating there. Don't be surprised if you find shark on
the menu.
Slide 9
Part 3 more information On land most food chains are short, but
scientists still have much to learn about them. They have even more
to learn about food chains in the seas. These chains are long. They
are also hard to study, because most of the plants and animals live
under water. In the water, as on the land, food chains begin with
green plants. Some of the plants are tiny-you`d need a microscope
to see them. Some are bigger. The green plants are food for many
tiny creatures, which become food for bigger creatures. Small fish
are eaten by bigger fish, which are eaten by even bigger fish. The
biggest, such as tuna, are at the top of the food chains-unless
they are caught by humans. Then one of them may turn up in your
tuna fish sandwich. Both tuna and you are one part of the food
chain that began with a tiny green plant. Food chains are found
wherever life is found. The far south of the world, Antarctica, is
icy and bitterly cold for much of the year. But in the summer its
seas are come alive. The water is rich with tiny plants. They fed
on by tiny animals. And these are fed on by small animals such as
krill, which look like shrimp. All these animals and plants are for
bigger animals, such as fish and squid. Many other animals come to
feast in these waters. There are seals, whales, and dolphins. There
are many seabirds, among them penguin. All the animals are linked
to the tiny green plants. The otters lived off the west coast of
North America. They lived in beds of giant seaweed, called kelp.
Every year thousands of otters were killed for fur. By the 1900`s
almost none where left. But as the otters disappeared, so did the
beds of kelp. And so did eagles, harbors seals, and fish. What had
happened? The answer was to lay down kelp. Kelp is a green plant at
the start of food chains. It is eaten by tiny animals that are
eaten by bigger animals that are eaten by fish. The fish are food
to eagles and seals, as well as people. Kelp is also eaten by spiny
animals called sea urchins. In eating, they may cut off stems at
the seafloor. The kelp floats away to the sea urchins are one of
the food otters like best. But when hunters kill the otters, there
was no one to eat sea urchins. The urchins destroyed the kelp beds.
Once the hunters stopped the otters had a comeback. They ate sea
urchins, and the kelp began to do well. When the kelp did well, the
fish came back-and did so eagles, seal, and fishermen.
Slide 10
Part 4 interesting facts The ocean is such a vast place that it
has a very complex food chain. A food chain is a system of
organizing living creatures into different levels. Each level is
dependent on the organisms below as their food sources. Sometimes
when issues such as oil spills or overfishing occur, it can destroy
entire populations of fish or other species. In this way, the
predators of those creatures (including humans!) are directly
affected, since they now have less food to eat. With less food, the
predators can go hungry and fall ill or die. On the other hand, the
prey of those same creatures may flourish since they are not being
eaten, and then start overpopulating. Even this is actually a bad
thing, since overpopulation can cause several other problems. As
you can see, the ocean food chain consists of a very delicate
balance. If something goes wrong, it creates a domino effect and
several other creature populations are affected in turn. The marine
food chain is divided into the four categories outlined below. Lets
read on to explore how life under the ocean works!
