1. What is Ecology?
Ecology (from Greek: οἶκος, oikos, "house"; -
λογία, -logia, "study of") is just the study of the
inclusive nature society dealing with
interactions of organisms with other organisms
and with the physical environment.
In biological taxonomy, kingdom and/or
regnum is a taxonomic rank in either
(historically) the highest rank, or (in the
new three-domain system) the rank below
Each kingdom is divided into smaller
groups called phyla (or in some contexts
these are called "divisions").
Currently, many textbooks from the United
States use a system of six kingdoms (Animalia,
Plantae, Fungi, Protista, Archaea, Bacteria)
while British and Australian textbooks may
describe five kingdoms (Animalia, Plantae,
Fungi, Protista, and Prokaryota or Monera).
The classifications of taxonomy are life,
domain, kingdom, phylum, class, order, family,
genus, and species.
How are organism placed into
•Cell type, complex or simple
•Their ability to make food
The number of cells in their
You are probably quite familiar with
the members of this
kingdom as it contains all the plants
that you have come
to know - flowering plants, mosses,
Plants are all multicellular and consist
of complex cells.
In addition plants are autotrophs,
organisms that make their own
With over 250,000 species, the
plant kingdom is the second largest
kingdom. Plant species range from
the tiny green mosses to giant
The animal kingdom is the largest
kingdom with over 1
million known species.
All animals consist of many
complex cells. They are also
Members of the animal kingdom
are found in the most diverse
environments in the world.
In 1983, scientists tool samples
from a spot deep in the Pacific
Ocean where hot gases and
molten rock boiled into the
ocean form the Earth’s interior.
To their surprise they
discovered unicellular (one cell)
organisms in the samples.
These organisms are today
classified in the kingdom,
Archaebacteria are found in
extreme environments such as
hot boiling water and thermal
vents under conditions with
no oxygen or highly acid
The hot springs of
Yellowstone National Park,
USA, were among the first
places Archaebacteria were
discovered. The biologists
pictured above are
immersing microscope slides
in the boiling pool onto
which some archaebacteria
might be captured for study.
Like archaebacteria, eubacteria
are complex and single celled.
Most bacteria are in the
EUBACTERIA kingdom. They
are the kinds found everywhere
and are the ones people are most
Eubacteria are classified in
their own kingdom because
their chemical makeup is
Most eubacteria are helpful.
Some produce vitamins and
foods like yogurt. However,
Streptococci pictured above,
can give you strep throat!
Fungi Fun Facts about Fungi
Some fungi taste great and
others can kill you!
Mushrooms, mold and mildew are all
examples of organisms in the kingdom fungi.
Most fungi are multicellular and consists of
many complex cells.
Fungi are organisms that biologists once
confused with plants, however, unlike
plants, fungi cannot make their own food.
Most obtain their food from parts of plants
that are decaying in the soil.
Slime molds and algae are protists.
Sometimes they are called the odds
and ends kingdom because its
members are so different from one
another. Protists include all
microscopic organisms that are not
bacteria, not animals, not plants and
Most protists are
unicellular. You may be
wondering why those protists
are not classified in the
Archaebacteria or Eubacteria
It is because, unlike bacteria,
protists are complex cells.
These delicate looking
diatoms are classified in the
5 Kingdoms and the Evolutionary Relationships
Classifications of Three Representative Species
HUMAN HONEY BEE RED OAK
Kingdom Animalia Animalia Plantae
Chordata Arthropoda Anthophyta
Class Mammalia Insecta Dicotyledones
Order Primates Hymenoptera Fagales
Family Hominidae Apidae Fagaceae
Genus Homo Apis Quercus
Species Homo sapiens Apis mellifera Quercus rubra
Organism Organ AtomMoleculeOrganelleCellTissue
Population - Group of interacting and interbreeding organism of the same
Community - Different populations(groups of different species) living
together interacting as competitors, predator and prey, or symbiotically.
Ecosystem - Organisms and their physical and chemical environments
together in a particular area. "The smallest units that can sustain life in
isolation from all but atmospheric surroundings."
Biosphere - Thin film on the surface of the Earth in which all life exists, the
union of every ecosystems on earth. This is a highly ordered system, held
together by the energy of the sun.
We have learned that Biology is hierarchical having at
least these levels:
Hierarchy of Biology
You might notice above that the level of organism is
highlighted, which is perfectly appropriate for this course!
So, while biology has all of those levels of organization,
we focus in this course mostly upon the individual
organism. The big idea for today is to understand that
when we look at the organisms, we also find that this
single layer itself has many layers in another dimension.
Rather than levels of organization, the organisms show
incredible diversity that we distinguish in a process often
There are many ways that the organisms might be
classified. Humans have traditionally grouped organisms
into some major groupings and then subgroupings within
each group. Humans love hierarchy, and so we naturally
understand how to organize a complex mixture of
organisms into groupings. This classification process
could have placed the organisms into categories of
usefulness...for example: those that provide food, those
that provide fuel, those that provide clothing, those that
perform work, those that provide pleasure, etc.
But of course plants and mammals can supply
food, and they can provide clothing. So this
kind of classification would be defective in that
it would put dissimilar organisms into the same
groups...and similar organisms into different
groups. So classification by usefulness would
be unnatural. Obviously something less
practical but more natural was needed to be
Carolus Linnaeus (aka Carl von Linné)
developed a hierarchical classification
scheme that continues to be
biologically useful to this day. This
method compartmentalizes all of the
organisms on the planet into
categories based upon their
So their form (morphology),
(function), reproduction (sexual
features and functions) are
used to group similar
organisms into a few major
groups called kingdoms. Sorry
ladies, but this was designed in
a male-dominated culture, so
there are no queendoms.
These major groups include
one for plants (named Plantae)
and one for animals (named
Kingdoms are obviously quite large and include
a lot of organisms. Obviously some more
classification was needed. So each kingdom was
divided into some subdivisions called phyla.
Each phylum was divided into classes, each
class into orders, each order into families, each
family into genera, each genus into species. So
biological classification has layers like an onion
too...it is hierarchical. The table below shows the
classification names at each layer (taxon) for six
Domain Bacteria Archaea Eukarya Eukarya Eukarya Eukarya
Plantae Fungi Animalia
Phylum Proteobacteria Euryarchaeota Phaeophyta
Class γ-proteobacteria -- Phaeophyceae Dicotyledonae Hymenomycetes Mammalia
Order Enterobacteriales Halobacteriales Fucales Rosales Agaricales Primates
Halobacteriaceae Fucaceae Rosaceae Agaricaceae Hominidae
Genus Escherichia Halobacterium Fucus Agaricus Homo
Species E. coli H. salinarum F. distichus R. multiflora A. bisporus H. sapiens
Rockweed Wild Rose Mushroom Human
The rows in this table represent the layers of classification among
organisms. The first column provides the name for each layer of
taxonomy. The remaining columns give the taxa for each of six
You might notice that in some cells of this table, there are multiple entries.
In taxonomy there may be multiple names in use for the same taxon. For
example, the phylum of the flowering plants is known as Anthophyta by
some and Magnoliophyta by others. These two names for the same
plants are called synonyms.
You might notice that some taxa in a particular row of the table share
similar endings (e.g. -ales for the family taxa). Again, while we might
portray taxonomy as "universal" there are some taxa in use that do not
NAMES OF ORGANISMS
The lowest row in this table gives the common name of the organism in the
column. Common names are, of course, not unique or universally understood and
so they have little place in science. So while they are included here for
illustration, in biology we tend to use only the scientific name for each species.
The scientific name for a species is the combination of the Genus name and the
Species epithet; it is thus a double name (a scientific binomial). You might notice
that your human binomial is Homo sapiens, sometimes abbreviated H. sapiens.
As a matter of common literacy for college students, you should learn your
binomial and how to spell it! Remember, you needed to know your personal
common name and how to spell it for first grade? Well, now we expect you to
learn one more! Notice how Homo sapiens ends in the letter s; that letter must be
present whether you are talking about one individual Homo sapiens or many
Homo sapiens. You are expected to know and spell this correctly from now on!
The other observation you might make of scientific names is that they are Latin
names often with Greek roots as well. Since these are Latin rather than English,
it is proper to show them in italics in print but should be underlined in
manuscript. The roots for our human binomial have meaning...Homo means self;
it identifies us as the organism responsible for the taxonomy! The epithet sapiens
means that we are capable of reasoning. Apparently we consider this to make us
unique among the organisms...but that is somewhat controversial as you might
Scientific names are not made by combining a descriptive name in English with
a -us suffix as is commonly observed on television cartoons. A coyote is not
called Wolfus stupidus or Caninus acmeensis. The coyote's correct binomial is
Canis latrans (dog barking) which makes it a member of the same genus (type of
organism) as the wolf (Canis lupus--dog wolf) and the dog (Canis familiaris--
dog household). In fact these three species can interbreed quite easily.
NUMBER OF ORGANISMS
A natural next question might be to quantify how big the
classification task really is. How many organisms are
there on Earth? This question is difficult to answer
because, in spite of the many years of human
observations and naming many, many organisms, we
know there are many species yet undiscovered and
undescribed on our planet! There is more work for your
generation of scientists to do!
If we consider the commonly-described six kingdom taxonomy,
reasonable estimates might be:
How Many Species?
Bacteria - 10,000
Archaea - 1,000
Protista - 15,000
Plantae - 270,000
Fungi - 100,000
Animalia - 1,200,000
Another interesting question is how a biologist knows whether two
organisms are different enough to be different species. In fact, this is
not a trivial question. In ancient days of science, a species concept
was advanced that if two organisms could successfully mate, then
they were the same species. Of course for some species, sexual
reproduction is unknown, so this could not be used for them. In
other cases, offspring are produced but are defective. For example,
if a mare horse is mated to a jack donkey they produce a mule.
Because mules are usually sterile, donkeys and horses were
considered to be different species. It is impractical if not impossible
to do the controlled matings to carry out this kind of "test" for the
millions of species listed above.
Plus it turns out that if we get away from mammals,
matings between quite different species can sometimes
produce not only viable offspring, but fertile ones too! If
you ask a botanist to identify an oak tree on campus,
there might not be a fast and direct answer. The red and
black oaks mate easily but the offspring double their
chromosomes spontaneously to become fertile new
species! These new species can mate true to their hybrid
type...but can also produce yet other "hybrid" species by
mating back with the parental species. So what we see in
the forest is, in fact, a hybrid swarm of strange
combinations of oak species.
You can imagine the difficulty for scientists of coming up with
unique names for each of the millions of species! Common
names are much easier to coin, fewer are needed, they can vary
from language to language, from location to location, and they
are not necessarily unique. One common name for an organism
is "Black-eyed Susan" but there are over 200 different species
that have this common name in one place or another. So
common names just do not provide the level of specificity
needed for science! Official Latin binomials are unique to each
species and the legitimate name is universal so that all scientists
can be sure of the species used in a particular study. Having said
it is also true that as scientists study the biological literature they
find that earlier binomials had been coined for a particular species.
Because the earliest name has priority over later coined binomials,
the binomial can be changed...and this leads to some synonyms for a
species. While all scientists should change to the earliest and official
binomial, sometimes the newer binomial has become so ingrained in
the literature that it continues to be used.
As an example of this phenomenon, I'll cite my own experience. I
was working with the Morning Glory vine. When it came time to
publish my work, I noticed that the plant physiologists who study
this plant use a newer (deprecated) binomial, Pharbitis nil, rather
than its "official" name, Ipomoea nil.
So which should I use in my paper? I decided to use the
correct name in the title and most of the article, but did list the
"common use" binomial as a synonym at the beginning of the
Taxonomy is a dynamic study, however! The groupings above
the level of Genus are often revised as new information makes
older groupings less than perfectly natural. In recent years,
information from DNA or protein sequences have been used
as characteristics to regroup organisms into different alliances
at higher levels of taxonomy. And, as we shall see, the
kingdom-level taxa have changed dramatically over the
years...and will continue to change!
NUMBER OF KINGDOMS
In the early to mid-1900s biologists considered all the
organisms to fall into two kingdoms...Plantae and Animalia.
This first level of classification seemed easy. Organisms that
could locomote (move from place to place) were animals, and
those that could not move were plants. Of course this simple
division was too superficial and put many sessile animals into
the plant kingdom. And among the plant kingdom there were
many organisms that just do not share many other attributes
with plants. Obviously the plant kingdom was artificial and had
to be divided into more natural groupings. So additional
kingdoms were needed.
One of the earliest kingdoms to be divided out were those
organisms that lacked a nucleus or organelles in their cells...the
prokaryotic organisms. Kingdom Monera was the result, and it
contained all the bacteria and related organisms of the prokaryotic
type. So now there were three kingdoms.
Among kingdom Plantae another large group with commonly-
shared characteristics was distinguished. They lacked cellulose cell
walls, using chitin instead. Their life history was more like animals
than like flowering plants. So a fourth kingdom was separated out
called Kingdom Fungi. This includes the molds, mildews, and
mushrooms. They really are not plants and are, in fact, closer to
animals in most of their characteristics.
Another group of organisms were really difficult to assign to any of
these kingdoms. Some had characteristics leaning toward prokaryotic
assignment to Monera, others had plant-like feature leaning toward
Plantae, others were sort-of fungal leaning toward Fungi, and yet
others were animal-like leaning toward Animalia. Making matters
worse, there were organisms that had features somewhere in-between
kingdoms. All of these difficult-to-classify organisms did have some
features in common...they were fundamentally unicellular and
aquatic. So an artificial (mixed descent) kingdom was created,
Kingdom Protista, to hold them. Obviously further study of Protista
has resulted in some of these species being moved to one of the other
four kingdoms. Further study of this group will create newer
kingdoms as well.
A bit later, further study among prokaryotic organisms discovered that
Kingdom Monera was also an artificial kingdom. Some of these species
have introns in their DNA, have different cell wall material, and many
other features in common, but separate from the common bacteria. So
Kingdom Monera was deprecated and split into two new kingdoms:
Bacteria for the true bacteria and Archaea for the rest. If you have
followed this discourse mathematically, we are up to six kingdoms. But
we are not done!
Kingdom Protista is admittedly artificial and needs a lot more study by
your generation of scientists to figure out the natural relationships.
Already, we have proposals to split out two more kingdoms from
Protista. These two groups have bodies that are multicellular (though
they behave mostly as independent single cells) in a unicellular
kingdom. But they also differ in their plastid ultrastructure and
Kingdom Stramenopiles and will include the brown algae,
chrysophytes, and diatoms. The red algae are also a unique
group deserving a Kingdom perhaps called Rhodophyta. So we
will soon be teaching about eight kingdoms... but there are
others in the works. It has been projected that the ultimate
resolution of Protista will end up in twelve or more kingdoms in
These changes in the number of kingdoms is shown in the table
below. Each row of this table represent a group of organisms.
The color of the cell represents the kingdom assignment. The
columns show the changes in those kingdom assignments over
time, so time progresses left-to-right across this table.
3 5 6 8
Bacteria Bacteria Bacteria Bacteria Bacteria
Archaea Archaea Archaea Archaea Archaea
Archezoans Archezoans Archezoans Archezoans Archezoans
Euglenoids Euglenoids Euglenoids Euglenoids Euglenoids
Chrysophytes Chrysophytes Chrysophytes Chrysophytes Chrysophytes
Green Algae Green Algae Green Algae Green Algae Green Algae
Brown Algae Brown Algae Brown Algae Brown Algae Brown Algae
Red algae Red algae Red algae Red algae Red algae
Slime Molds Slime Molds Slime Molds Slime Molds Slime Molds
True Fungi True Fungi True Fungi True Fungi True Fungi
Bryophytes Bryophytes Bryophytes Bryophytes Bryophytes
Tracheophytes Tracheophytes Tracheophytes Tracheophytes Tracheophytes
Protozoans Protozoans Protozoans Protozoans Protozoans
Myxozoans Myxozoans Myxozoans Myxozoans Myxozoans
Taxonomists who tend to recognize more rather than fewer
divisions are called "splitters" while those who tend to put
groups together into fewer divisions are called "lumpers." It
would seem that new information is supporting splitters more
than the lumpers these days. But most biology textbooks
certainly are written by lumpers. Authors seem to talk about six
kingdoms in the taxonomy chapter, but then the book table of
contents is clearly divided into two major units...plants and
animals...as if there were really only two kingdoms and as if the
year is 1955. This is why I am writing these pages for you here!
There is no biology book in print now that takes the approaches
we take here.
Why are the number of kingdoms or other levels of taxonomy
so controversial? Why aren't the species groupings absolutely
clear? Part of the answer to these questions lies in the simple
fact that biology has so many species and that we know
relatively very little about most of them. We need an army of
biologists to figure out this mess of millions of species on our
planet. So many of us are tied up studying just a few species,
that most are almost completely unstudied. There is a lot of
room for you in this field!
Another important basis for the lack of consensus and lack of
clarity is that the diversity of organisms is the result of
natural evolutionary processes that are not neatly or easily
packaged into the boxes or onion layers of taxonomy.
Because of this origin for the diversity, a new thrust in
taxonomy has developed since the 1960s. This new way of
thinking about taxonomic relationships has focused upon the
evolutionary pathways by which species evolved and by
which they are naturally related to each other. One could
think of this as the study of phylogeny.
In evolution, species diverge to form a branching tree-like
organization as time progresses, and so this new taxonomy is
about branching patterns in evolution through time. It is called
cladistic phylogeny or simply cladistics. Rather than thinking
about kingdoms, phyla, classes, orders, families, genera, and
species as nested containers for organisms, we think of how
they are related to each other by virtue of the characteristics
they share, and how they branched about by virtue of the
characteristics they do not share.
A population is defined as all the organism within
an area belonging to the same species. At this
ecological level, ecologists are interested in
the growth and regulation of population
size, as well as the factors behind them.
1. Uniform Distribution – happens if there is auto
competition for resources such as food, water,
2. Random Distribution – distribution that can be
found in places where environmental
conditions are relatively uniform.
3. Clumping – most common pattern it happens
due to varying environmental conditions.
Population density is the number of individuals of a
certain species per unit area or volume, and
population distribution is the pattern of dispersal of
them within that area. They both are
indispensable variables for ecologists to
analyze and discover the spreading pattern of a
certain species within a certain area and time.
The density and distribution of a population
changes with time, due to abiotic
factors(inorganic factors) as well as biotic
factors(organic factors). Abiotic factors that
could have an influence on a population
include temperature, rainfall, type of soil
and so forth; biotic factors are those that are
related to other living things
Factors that affect population size
Theoretically, there exist 2 distinct and simple
growth patterns, or mathematical models for
population growth. In the first one, only one
reproductive chance is given to members of
the population during in their entire lifespan.
Once mission accomplishes, they die. Many
insects and annual plants reproduce in this
manner. In the other model, members
experience many reproductive events
throughout their lifetime. Most vertebrates,
and trees have this pattern of reproduction.
A community is comprised of all the various
populations interacting in a area. An example
of a community is a coral reef where
numerous populations of fishes, crustacea
and corals exist and interact. Ecologists try
to know at this level how different
relationships like predation and competition
are influencing the organization and
evolution of a community.
Communities distinguish from each other by
two characteristics: composition and
diversity. The composition of a community is
simply a listing of the various species in the
community. The diversity digs deeper than
mere composition in that it involves both
species richness(the number of species) as well as
evenness (the relative abundance of different
A habitat is an environment wherein an organism lives and
reproduces, while the ecological niche is the functional
role the organism plays in its community, including its
habitat as well as the interactions with other organisms.
Niche includes everything(e.g. resources an organism
needs to meet its energy, nutrient, and survival
demands) and every aspects of the way(e.g. the
environmental features it needs to hunt and to
escape successfully) an organism live with the
environment, since it's difficult to delve into one
niche completely, most observations concentrate on
certain aspects of it.
Interspecific competition occurs when members of
different species try to utilize the same resource
like light, space, or nutrients that is in limited
supply, or when their niches overlap. If it is
unlimited, no competition would have been
triggered. Competition leads to several
possible outcomes. One of them is the
extinction of one of the competitors.
In predation, one organism, called the predator feeds
on another, called the prey.
The predators now are provided with plenty of
prey to feed on, so the population increases as
that of prey decreases. Again, the predators'
increased number overconsume the prey, as
the prey population declines, so does the prey
A symbiotic relationship, or symbiosis is one in which
members of two populations interact very closely.
Parasitism resembles predation in that an organism called
a parasite derives nourishment from another called the
host(just as the predator derives nourishment from
its prey), though parasites also take hosts as habitats
and springboards to transmit themselves to other
hosts. Parasites appear in all kingdoms of life. Some
of the frequently heard of parasites include
viruses(e.g., HIV), bacteria(e.g., strep infection),
protists(e.g., malaria), fungi(e.g., rusts and smuts),
plants(e.g., mistletoe), and animals(e.g., leeches).
Commensalism is a symbiotic relationship wherein one species is
benefited and the other is neither benefited or harmed. Well known
instances are those in which one species provides a habitat or a
means of transportation for the other.
Example of Commensalism
Animalia: Barnacles attach themselves to the backs of whales
and the shells of horseshoe crabs to get a free home and ticket
for transportation. Remoras are fishes that attach themselves to
the bellies of sharks by means of modified dorsal fin acting as a
Plantae: Epiphytes grow in branches of tree in order to receiver
light, but not to take nourishment from the trees. Instead, their
roots obtain nutrients and water from the air.
Mutualism is a symbiotic relationship in which both species
benefit. In many cases, mutualistic relationships help organisms
obtain food or avoid predation. As with parasitism, it's possible
to find examples of mutualism in all kingdoms.
Example of Mutualism
Human & Bacteria: Human cannot synthesize vitamins by
themselves, but can benefit from some bacteria residing in their
intestinal tract that make vitamins. Meanwhile, bacteria are
provided with food.
Termites & Protozoa: Termites rely on the protozoa in their
intestinal tract to digest wood.
To sum up, symbiotic relationships do occur between species,
but the three patterns we provided may be too simple to
embrace all the natural forms of symbiosis. We were just
skimming roughly. Many other derivative forms of symbiosis
are developed, look for other materials if you are interested.
Competition – limited resources are similarly
used by two or more population.
1. Intra – species competing with the same
2. Inter – species competing with different
Species Diversity – measured in terms of
number and relative abundance of species
found in a community.
1. Species Diversity in Ecosystem – gives
attention to the ecological.
2. Species Diversity in Geographic Region
3. Species Diversity in Evolutionary Period –
original pattern and extention.
Species Stability – species that
have existed in a community
for a long period of time. It
also determined by the
relatively constant number of
species and population size.
1. Optimum Temperature
2. Abundant supply of food
3. Reproductive Capability
Ecosystem – a community of organism functioning
together and interacting with physical
Components of Ecosystem
1. Abiotic Components
2. Biotic Components
Abiotic components are such physical and chemical
factors of an ecosystem as light, temperature, atmosphere
gases(nitrogen, oxygen, carbon dioxide are the most
important), water, wind, soil. These specific abiotic
factors represent the geological, geographical,
hydrological and climatological features of a
particular ecosystem. Separately:
Water, which is at the same time an essential
element to life and a milieu
Air, which provides oxygen, nitrogen, and carbon
dioxide to living species and allows the
dissemination of pollen and spores
Soil, at the same time source of nutriment and physical
support. The salinity, nitrogen and phosphorus content,
ability to retain water, and density are all influential.
Temperature, which should not exceed certain extremes,
even if tolerance to heat is significant for some species
Light, which provides energy to the ecosystem through
Natural disasters can also be considered abiotic.
According to the intermediate disturbance hypothesis, a
moderate amount of disturbance does good to increase
Example of Water Requirements of Plants
As we all know, water is essential for life and all organisms
depend on it to survive in especially desert areas. Plants can be
classified into 3 groups according to their water requirements:
Hydrophytes: plants which grow in water, e.g. water-lilies and
Mesophytes: plants with average water requirements, e.g. roses,
Xerophytes: plants growing in dry environments where they
often experience a shortage of water, e.g. cacti and often
Adaptations of plants to survive without water include
reversed stomata rhythms, sunken stomata, thick cuticles, small
leaves(or the absence of leaves) and the presence of water-
The living organisms are the biotic components of an
ecosystem. In ecosystems, living things are classified
after the way they get their food.
Autotrophs produce their own organic nutrients for
themselves and other members of the community;
therefore, they are called the producers. There are
basically two kinds of autotrophs, chemoautotrophs
and photoautogrophs. Chemautotrophs are bacteria
that obtain energy by oxidizing inorganic
compounds such as ammonia, nitrites, and sulfides ,
and they use this energy to synthesize
carbohydrates. Photoautotrophs are photosynthesizers
such as algae and green plants that produce most of the
organic nutrients for the biosphere.
Heterotrophs, as consumers that are unable to produce, are
constantly looking for source of organic nutrients from
elsewhere. Herbivores like giraffe are animals that graze
directly on plants or algae. Carnivores as wolf feed on
other animals; birds that feed on insects are carnivores,
and so are hawks that feed on birds. Omnivores are
animals that feed both on plants and animals, as human.
Detritivores are organisms that rely on detritus, the
decomposing particles of organic matter, for food. Earthworms
and some beetles, termites, and maggots are all terrestrial
detritivores. Nonphotosynthetic bacteria and fungi,
including mushrooms, are decomposers that carry out
decomposition, the breakdown of dead organic matter,
including animal waste. Decomposers perform a very
valuable service by releasing inorganic substances that
are taken up by plants once more.
Everything needs energy to motion, living
things are no exceptions. Sun is the ultimate
source of energy for every ecosystem. The
energy flow of an ecosystem starts the
moment photosynthesizers capture sun light
and transform it into a stock of organic
compound like glucose that stores heat and
energy for later use, and ends until the
energy is used up or released into the
surroundings in metabolic processes.
Photosynthesis explains how energy from the sun is
captured by green plants and used to make food. Most of
this energy is used to carry on the plant's life activities.
The rest of the energy is passed on as food to the next
level of the food chain.
These figure shows energy flow in a
simple food chain. At each level of
the food chain, about 90% of the
energy is lost in the form of heat. The
total energy passed from one level to
the next is only about one-tenth of the
energy received from the previous
organism. Therefore, as you move up
the food chain, there is less energy
available. Animals located at the top
of the food chain need a lot more
food to meet their energy needs.
NOTE!! Each organism in the food
chain is only transfering one-tenth of
its energy to the next organism.
Try this fun activity with your class to help
make this more clear. Think of energy as root
beer. The teacher will represent the sun and
four students will represent the organisms in a
food chain: a plant, an insect, a sparrow and a
hawk. You will need a liter of root beer,
graduated cylinders, and an eyedropper.
Reviewing the above diagram, we find that:
•The sun has one liter of root beer (energy) to give.
•Of that, the plant gets one-tenth or 100 milliliters.
•The mouse gets 10 milliliters from the plant.
•The hawk gets 1 milliliter from the mouse.
•When the hawk dies and is decomposed by the mushroom, the mushroom gets only one-
tenth of a milliliter!
When the root beer has been distributed in the correct amount to each
participating student, they can drink their share.
The extra root beer that the sun does not give to the plant, is likened unto the
90% energy lost to the environment. You as the teacher to simulate this
energy loss, pour the remaining root beer down the drain and listen to the
moans of your students!
After doing the activity, answer these questions.
1.Which organism was most satisfied by the amount of "energy" he or she
received? Which organism was least satisfied?
2. What happened to the 900 milliliters from the sun that the plant didn't
3. How much "energy" was USED by the insect?
4. What consumer in the food chain is going to have to eat the most food to
meet their energy needs?
5. Why can't a food chain have an infinite number of links?
You can see that because energy is lost at each step of a food chain, it takes a
lot of producers to support a few top consumers. The food pyramid below shows
an example of this.
Notice that if there were a 1000 units of energy at the producers level the
primary consumers would receive 100 units of energy, the secondary
consumers would receive 10 units of energy, and the tertiary consumer would
receive 1 unit of energy. This pyramid helps to demonstrate the loss of energy
from one level of the food chain to the next.
Primary productivity is the term used to describe the amount of
organic matter an ecosystem produces from solar energy within a
given area during a given period of time. Related to the concept,
gross primary productivity is the total amount of organic matter
produced by all autotrophs in an ecosystem, including that used by
themselves. It is incurred through the process of
photosaynthesis that is carried out by green plants, algae, and
some bacteria. Net primary productivity, on the other hand, is
defined as the total amount of energy fixed per unit of time minus
the amount of energy expended by the metabolic activities of the
photosynthetic organisms in the community, denoting the amount of
organic matter produced by autotrophs that is available for
Example of Primary Productivity
In tropical forests and in marshlands, between 1500
and 3000 grams of organic material are normally
produced per square meter per year.
Corresponding figures for other communities are:
temperate forests, 1100 to 1500 grams; dry deserts,
200 grams. For such highly productive communities
as estuaries, coral reefs, and sugarcane fields, the
figures may range from 10 to 25 grams per day, for
comparable annual yields of 3600 to 9100 grams.
Biomass, is the net weight of all organisms
living in an ecosystem, which, increases as
a result of its net production. Secondary
productivity is defined as the rate of
biomass accumulation by heterotrophs
(herbivores, carnivores and detritivores).
Food webs refer to the complicated feeding
relationships that exist among organisms in
natural ecosystem. The ocean food web
displayed below, however, is just the
grazing food web that begins with green
plant, or the producer.
(just one path of energy)
(everything is connected!)
Food Chains & Food Webs
Do you like to play games? If you do, you will need energy. Every time
you run or jump, you are using up energy in your body. How do you get
the energy to play? You get energy from the food you eat. Similarly, all
living things get energy from their food so that they can move and grow.
As food passes through the body, some of it is digested. This process of
digestion releases energy.
A food chain shows how each living thing gets its food. Some
animals eat plants and some animals eat other animals. For example,
a simple food chain links the trees & shrubs, the giraffes (that eat
trees & shrubs), and the lions (that eat the giraffes). Each link in this
chain is food for the next link. A food chain always starts with plant
life and ends with an animal.
1.Plants are called producers because they are able to use light
energy from the Sun to produce food (sugar) from carbon dioxide and
2.Animals cannot make their own food so they must eat plants and/or
other animals. They are called consumers. There are three groups of
a. Animals that eat ONLY PLANTS are called herbivores (or primary
b. Animals that eat OTHER ANIMALS are called carnivores.
- carnivores that eat herbivores are called secondary consumers
- carnivores that eat other carnivores are called tertiary consumers
e.g., killer whales in an ocean food web ... phytoplankton → small fishes →
seals → killer whales
3. Animals and people who eat BOTH animals and plants are called omnivores.
4. Then there are decomposers (bacteria and fungi) which feed on decaying matter.
These decomposers speed up the decaying process that releases mineral salts back into
the food chain for absorption by plants as nutrients.
Image Map of the Nitrogen Cycle - What happens in the soil?
Do you know why there are more herbivores than carnivores?
In a food chain, energy is passed from one link to another. When a herbivore
eats, only a fraction of the energy (that it gets from the plant food) becomes
new body mass; the rest of the energy is lost as waste or used up by the
herbivore to carry out its life processes (e.g., movement, digestion,
reproduction). Therefore, when the herbivore is eaten by a carnivore, it
passes only a small amount of total energy (that it has received) to the
carnivore. Of the energy transferred from the herbivore to the carnivore,
some energy will be "wasted" or "used up" by the carnivore. The carnivore
then has to eat many herbivores to get enough energy to grow.
Because of the large amount of energy that is lost at each link, the amount of energy that is
transferred gets lesser and lesser ...
1.The further along the food chain you go, the less food (and hence energy) remains
1.Most food chains have no more than four or five links.
There cannot be too many links in a single food chain because the animals
at the end of the chain would not get enough food (and hence energy) to
Most animals are part of more than one food chain and eat more than one
kind of food in order to meet their food and energy requirements. These
interconnected food chains form a food web.
The following is a possible food web:
Note that the arrows are drawn from food source to food consumers ... in
other words, you can substitute the arrows with the words "eaten by"
A change in the size of one population in a food chain will affect other
This interdependence of the populations within a food chain helps to maintain
the balance of plant and animal populations within a community. For example,
when there are too many giraffes; there will be insufficient trees and shrubs for
all of them to eat. Many giraffes will starve and die. Fewer giraffes means more
time for the trees and shrubs to grow to maturity and multiply. Fewer giraffes
also means less food is available for the lions to eat and some lions will starve
to death. When there are fewer lions, the giraffe population will increase.
This ocean food web displayed above shows
that krill and other herbivorous plankton
feed on phytoplankton, the producer, while
birds and fish feed on krill, but they are in
fact omnivores because they also feed on
plankton; squid hunts fish for food while
enjoying some plankton once in a while as
well. These herbivores and omnivores all
provide energy and nutrients for a number of
different carnivores, such as seals and whales.
This decomposer food web is modeled upon the
detritus food chains that are based on mangrove
leaves which fall into shallow estuarine water of
South Florida. The bacteria and fungi of decay
are the decomposers, but they can be food for
other detritivores. Note that detritivores are not
necessarily bacteria or fungi, they can also be
large scavengers such as crabs and shrimps that
feed on dead organisms and also the cast-off
parts of them.
There are producers and consumers in a food web.
Producers are those able to synthesize food for
themselves, like phytoplankton; and all the others
are consumers that rely on producers directly or
indirectly for a living. Among these consumers,
several different levels may be recognized. Primary
consumer, or herbivores, feed directly on the green
plants; secondary consumers, carnivores and parasites
of animals, feed in turn on the herbivores.
Decomposers or detritivores break down the organic
matter accumulated in the bodies of other
All these levels, if we link them one to
another in a straight-line manner, according
to who eats whom, we have food chains.
Food chains are selected single-lane food
relationships in a series among organisms
from a more complicated food web, as
Phytoplankton ==> krill ==> fish ==> seal==>
Diagrams like this that tell who eats whom are
called food chains. And a trophic level is all the
organisms that feed at a particular level in a food
chain. In the grazing food web given at the
beginning of the section, going from bottom to
top, the phytoplanktons are primary
producers(first trophic level), the first herbivores
that feed on the them, namely the krills and
herbivorous planktons are primary
consumers(second trophic level), and the next
group of animals are secondary consumers(third
Numbers indicated in the diagram are measures of
biomass, and the widths of the colored rectangles are
so drawn that the proportions are respected. A plant
fixes about 1% of solar energy that falls on its green
parts. The successive members of a food chain, in
turn, process into their own bodies about 10% of the
energy available in the organisms on which they
Aside from pyramids of biomass, there are also
ecological pyramids of numbers and energy, more or less
in the same impressive construction that slender
representations of top consumers are set upon a
huge foundation of that of producers. At the top of
most food webs, just imagine the number of plants
that have to be grown to support all human being.
Human Beings... masters of this planet?
Are we humans beings really the masters of this planet? Do we have the authority to
self-righteously assume global dominance? The following article is my view to the
questions. It is certainly not definitive. It is just an expression of my own thoughts and
In my view, we should not assume that our human kind is central to the
world and the planet at large. A human economic system should ideally also
take into account the well being of the entire ecosystem, which is body of
Mother Earth. I will tend to regard the Mother Earth as a living consciousness
with her various elements (water, air, wildlife, etc) constantly seeking to
remain in harmonious equilibrium. Come to think of it, isn’t this quite like the
way the body of a living being functions?
Perhaps, economy should not be about humans for humans only. We tend to
see ‘less-than-holistically’ and believe that money-making has little or nothing
to do with the welfare of our Mother Earth and the ecosystem. But the fact is
we humans do take sustenance from the atmosphere, animal and plant
kingdoms; therefore we are dependent upon other species and resources on
Earth. As such, human activities should be accounted for within a equation
that does not place the human species upon a pedestal (which is being
treated as superior); but rather assigns the ’so-called intelligent biped’
objectively with other species and elements of this diverse planet. In my
opinion, the current human activities are simply too self-absorbed within our
own kind. The truth of things is that everything, ‘however insignificant it may
appear to be, is in actual fact, unique. “Feeling special” and “above others”
are simply beliefs concocted by the human psyche, and have relevance only
in a human society.
Holistic & equitable replenishment & redistribution amongst all elements and
species on Earth should be the a central theme for sustainable living, instead of
the human biased “competitive” model. I feel that perhaps recycling of used
materials may not be enough. Humans, being the so-called intelligent life form on
Earth should actively develop sciences that deal with replenishment of plants,
animal kingdoms and elements, keeping resources in equilibrium.
To achieve all that, perhaps the very mindset that first sets competition in motion
has to be re-evaluated. Well, this ideal is certainly easier said than done.
Global Warming And Climate Change - How It Effects You
And How You Can Help
The climate of the Earth is always changing. In the past it has
altered as a result of natural causes. Nowadays, however, the
term climate change is generally used when referring to
changes in our climate which have been identified since the
early part of the 1900's. The changes we've seen over recent
years and those which are predicted over the next 80 years are
thought to be mainly as a result of human behavior rather than
due to natural changes in the atmosphere.
The greenhouse effect is a very important factor in climate change
as it relates to the gases which keep the Earth warm; the extra
greenhouse gases which activity create are thought to pose the
Scientists across the World are looking at the evidence of climate
change and are also using computer models to come up with
predictions for our future environment and weather.
Looking at the knock-on effects of climate changes is a huge part of
the researcher work and could cause a larger, more immediate
As we are likely to see an increase in rainfall and as a result sea
levels rise, we could be more affected by flooding in the coming
years and low
lying seaside areas could be the first victims of climate change.
How will the health of humans and animals be affected by global
warming, malaria – a disease spread by mosquitoes - for example, has
been discovered in “cooler” countries which were never previously
affected by the disease, and freak invasions of locusts are causing
problems in agricultural areas in recent years. Wildlife also will be
affected, already certain species have been found in new cooler areas
as they move closer to the poles to escape the gradually growing heat
– and in the sea, as sea temperatures rise what will the effects on
The list of things we need to think about which will be affected by
climate change is endless.
The only way to slow global warming and climate change is for
humans to stop producing so much CO2 and other gasses and
stop destroying our forests, which are the only things we have to
produce more much needed oxygen in the air. Changing to use
alternative energy sources, such as solar power, wind power,
geothermal, water power and even nuclear energy are beginning to
become increasingly popular.
Also building materials that are used in homes can help us to
reduce the amount of energy we use – if your house has suitable
insulation, and suitably glazed windows the need to use heating
may be reduced by a few months a year, there fore creating less
atmosphere destroying gasses
Causes Of Global Warming
One of the most serious environmental crises facing us today is global
warming. It is the gradual increase of the earth and ocean temperature as a
result of the build up of certain gases which trap heat in the atmosphere
causing the earth to warm up. These heat-trapping gases are also called
Although carbon dioxide is said to
be the cause of more than 60% of
global warming, there are other
substances which cause global
warming as well, including methane,
chlorofluorocarbons, and nitrous
oxides. Did you ever asked yourself
why the earth is heating up? Some
may say it is a natural phenomenon,
others may claim that man made the
changes. As a matter of fact, natural
causes and human activities are the
factors which influence global
Studies claim that billion years ago, long before man exists, there is already a
warming of the planet. One of the natural cycles which believed to cause the
rise of temperature is the sunspots cycle. For instance, explosions of the
sun’s surface produces heat which can hit the earth causing intense
temperatures. Another natural factor believed to affect global climate is the
earth orbit and tilt.
Any changes of the earth orbit can cause the planet to move closer or farther
from the sun. Therefore it is one of the culprits for global warming. Evidence
proved that plate tectonics caused poles to be isolated from warm ocean
currents. Thus it can affect our climate. Furthermore, another natural factor for
global warming is the release of methane gas from wetlands and arctic
tundra. One example of greenhouse gas involved in global warming is
Although greenhouse gases occur naturally to keep the Earth temperature
stable to maintain life, human activities increase the concentration of these
gases in the atmosphere. As concentration of greenhouse gases in the
atmosphere increases, the atmosphere is capable of absorbing more heat. As a
result, the earth tends to warm up. In this case, man is believed
to be a factor for global warming. The rise of Industrial Revolution dramatically
increases the concentration of Carbon dioxide and other greenhouse gases in
the atmosphere at rates much faster than the earth can cycle them.
Transportations, factories, electricity from coal-fired power plants produce
carbon dioxide and other heat-trapping gas in the atmosphere. Cutting down
trees is another significant source of greenhouse gases, because fewer trees
mean less conversion of carbon dioxide to oxygen. In addition, research shows
that burning wood and fossil fuels such as gas, coal, and oil contributes carbon
dioxide; methane is released from livestock and coal production; and
agricultural and industrial processes produces nitrous oxide.
Pollution in the Modern World Leads to Modern Problems
In this modern world as scientists produce new technology for the
welfare of mankind it only results in new luxuries being produced.
This attitude by people towards the environment is changing because
they want more and more luxuries and they are destroying the
environment for this reason.
They use instruments like fridges, air conditioners etc that release
C.F.C’s in the environment which in turn deplete the Ozone layer but
these gadgets not used before the 19th century, according to recent
researches the depletion of ozone has increased by about 50% in the
20th century. The uncontrolled deforestation to built buildings for their
own accommodation is increasing the oxygen content in the
atmosphere, which is leading to global warming.
The increasing riots also increase pollution as many cars are set on fire during
the riots. This increases the temperature of that place as well as the global
temperature; wars are also producing much type of pollutions like air, water,
land, noise and radiation. The testing of missiles produce toxic radioactive
gases like Radon, Xenon, So2 ,Co etc.
The increasing use of plastic bags leads to the pollution of the land and the
sea. These plastic when buried in the earth do not decompose and convert that
land into bad land not suitable for agriculture; throwing these plastic bags into
the sea kills the fish. The use of loud speakers at late night parties, marriages
Noise come from all over the place. Noise from road traffic, jet planes, jet skies,
garbage trucks, construction equipment, manufacturing processes, lawn
mowers, leaf blowers, and boom boxes, to name a few, are among the audible
litter that are routinely broadcasted in the air or from road traffic, jet planes, jet
skies, garbage trucks, construction equipment, manufacturing processes, lawn
mowers, leaf blowers, and boom boxes lead to increase
in sound pollution which have many harmful effects
like disturbance in sleep, deafness etc.
At the end I would like to say that if this trend of
modernization continues we will ultimately change
the earth into a place, which will be full of pollution
and unsuitable for flora and fauna.
Clean Sources of Energy to Avoid Contributing to Global
Many people wonder what they can do to help dampen the effects of the
climate crisis. One method of doing so incorporates the usage of ‘clean'
energy; that is, energy that does not contribute to the levels of greenhouse
gas present in our atmosphere. There are several sources of clean energy,
and although it may cost more, the benefit on the planet's ecosystem is well
worth the extra money. Commonly known as ‘green power', the Environmental
Protection Agency has formed a partnership to help encourage the usage of
these alternative sources of energy.
Wind energy is one option when it
comes to renewable power. Large
spinning turbines harvest the
movement of the air, and the energy
is transferred into an electricity
generator for usage in any
application. While it's not available
everywhere, wind energy represents
one of the fastest sectors of growth
when it comes to alternative power
sources, and it is consequently one
of the most widely used alternative
sources. As a matter of fact, since
the year 2000, the number of wind
turbines present in the United States
has more than doubled!
Solarpower is another significant source of renewable energy. Solar cells
known as photovoltaic's are placed on sun-catching areas such as the roof of a
house. These cells turn light energy into electricity, and enough electric panels
can provide power for an entire home, leaving you independent of the energy
Geothermal energy represents a source of energy that is not commonly
discussed. Heat from underneath the earth's surface is harvested as steam,
which helps to spin a turbine much in the way of wind power. The spinning
motion is sent to an electricity generator, and the power can be used in any
Low impact hydropower represents another significant
source of renewable energy. Incorporating the use of a
turbine, hydropower is created in streams and rivers
which produce enough of a force to properly spin the
turbines. Many aspects of hydropower need to be
approved to ensure that the turbines do not significantly
effect wildlife that may be living in the area where the
energy is being harvested. Most hydropower sources do
not dam a river up; they operate with the river in free-
flow as to minimize the effect on the environment.