 Prof.
Patrizia Macrì, after having told us about the wood ecosystem, asked each
of us to draw an element of the wood that we would have liked to be. Then
she gave one of us a skein. He said loudly who he was, and threw the skein
at anyone who, in the ecosystem, was related to him. Time going by, we
made up a big web, and understood that nothing should be touched or
manipulated.
Every living being is necessary, from
microscopic ones to predators. When an herbivore eats a plant, and a carnivore
eats that herbivore, such process is called alimentary chain. It is usually
formed by a carnivore, an herbivore and a vegetable; sometimes a carnivore might
even appreciate a wide range of other meat eaters.
Example: The leaf is eaten by the worm, swallowed by the sparrow, victim of the
eagle. If one of those was suddenly missing, say the sparrow, the eagle would
have to starve, but when the leaf disappeared, the whole chain would break.
The alimentary chain, therefore, is a sequence of the events occurring in an
environment frantically lived by a multitude of animal and vegetable elements.
Each of them is a ring. The first consists of the vegetables, the producers:
through the photosynthesis they produce the food they need, and are so called
autotrophic.
The consumers are animals, needing substances for living in the environment,
hence eterotrophic. Decomposers are organisms that feed on dead substances, and
transform them in elements helpful for the plants. Bacteria are helped by worms
and insects that feed on leftovers and organic waste.
Consumers are distinguished between herbivore, carnivore and omnivorous:
HERBIVORE:
Fed on vegetables (leaves, roots and grass)
CARNIVORE:
Fed on herbivores. Some of them, say hawk and lion, are carnivore predators, as
they assault and kill other animals.
OMNIVOUROUS:
Fed on both (man included)
The alimentary chain could be called 'life chain', since in fact each living
being is busy in looking for food to survive. |
