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Contents
PHOTOGRAPH ON PAGE 1:
The water is stained a deep
red from iron ore washing
at a mine in Michigan.
Ecology:
Introduction and
Background
Page 6
Studying Nature
Page 16
Major Biomes
of the World
Page 28
Life in
the Water
Page 66
Humans and
the Biosphere
Page 82
The Oldest
This unique science was so complex and species that compete with one another for
encompassing that it was not until the the same resource. This exploration will also
19th century that its scientific reveal surprising relationships in which
Science . . . and
foundations could be laid, formal study could species mutually benefit from one another.
begin, and the word “ecology” could come
into existence. This book serves as a detailed We will then be ready to understand
the Most Recent
introduction to the subject. how nonliving, physical
environments influence, modify,
We will begin by learning what and even determine the characteristics of
ecology is and what it is not. (At this complex bundle of interactions. At this
times the word has been used moment, we will define the word
Long ago when people still lived in
WHEAT HARVEST
incorrectly as a synonym for environmental “ecosystem” and learn how materials and
A productive soil is much more caves—perhaps at the same time when
than “dirt.” Farmers know that to
protection.) Later, we will look at how living energy pass through its living and nonliving
produce a good crop it is they developed habits that were
important to maintain the things are classified, before moving into the parts. These concepts are needed for the
ecological balance of the soil. different from those of other animals—
study of the environments in which they live: next step, the examination of each of the
humans began to practice ecology. They
the land, water, and air. world’s major biomes. We will examine both
became keen observers of nature through
terrestrial and aquatic biomes and the
such basic and instinctive actions as tracking
The next stop along this journey, filled characteristic plant and animal species
both large wild animals and small prey,
with exciting information and found within them, including those species
discerning edible plants from poisonous ones,
marvelous illustrations, will be devoted that may be in danger of extinction. Finally,
and noting the time of year when different
to ordering and organizing the surprising we will look at the place that people occupy
plants could be gathered. From necessity and
diversity of living organisms on Earth. Living in the biosphere—the ways in which their
inherent curiosity, humans began to learn
things are first grouped into populations activities change nature and even create
about the relationships between living things
according to their kinship, then into new ecosystems. In the urban centers,
and the environment. As the field of ecology
communities according to the spaces they different species have developed novel
grew, its focus went beyond the simple
share. The exploration into the ways in strategies to cope with the challenges of
cataloging of living things in the world.
which organisms interact will show that life in the “concrete jungle.” Despite the
Ecologists also became interested in
some interactions can be very cruel, such as damage to the environment caused by
understanding how living things function
those between predators and prey or those human beings, there is a ray of hope: human
and how they interrelate with one another
between different ingenuity can also be used to protect the
and with the environment—to explain
environment and to reduce the harm
that peculiar element that makes the
caused by their activities.
Earth unique: life.
Ecology: Introduction
WATERWAYS WHAT IS ECOLOGY? 8-9
Can everyday life be imagined without
water? Environmentalists say that in the THE FIVE KINGDOMS 10-11
and Background not-too-distant future it may be necessary
to confront this possibility, given that THE SOIL 12-13
stocks of usable water are declining.
WATER AND AIR 14-15
A
ny landscape, from an arid to be busy with some task. How can we monumental task. As a first step, we will classify living things into five major
desert to a rainforest, conceals understand what takes place in the investigate the various media in which life kingdoms, which in general correspond
an astonishing diversity of environment? How can we determine the occurs—water, land, and air. (Air is as to animals, plants, fungi, prokaryotes,
organisms in action. Each mechanisms that govern the actions of important as land and water, even though and protists. Turn the page to begin your
appears to play a role and seems living things? Understanding ecology is a it is much less populated.) Then we will exploration into the world of ecology.
8 ECOLOGY: INTRODUCTION AND BACKGROUND ECOLOGY
What Is Ecology?
The Flow of Energy Distribution
In studying ecosystems, it is extremely important Environmental factors (such as climate, geography,
to determine the way in which energy is transferred and soil composition) determine the distribution of
from organism to organism. species in different biomes.
Some branches of biology, such as zoology and botany, are dedicated to the study of living things.
Other sciences, such as geology and meteorology, deal with the nonliving parts of the Deserts of ice are among the biomes having the
poorest biodiversity. Some of the adaptations of the
environment. These nonliving parts include the composition of the Earth, weather phenomena, and organisms that live there, however, are surprising.
volcanoes. Ecology, however, takes a little from each of these sciences and looks at the interactions
among organisms in a community and between the community and the environment. In this way,
Energy from the
ecology seeks to explain biodiversity, the distribution of species, and the way ecosystems function. Sun is taken in by
plants and passed
It also endeavors to foresee the consequences that might result from future changes.
along to the deer that
eat the plants. It
eventually reaches
the lion, which preys
40,000 on the deer.
Levels of Organization
To help understand the complexity of life, ecologists
The number of plant
recognize different levels of organization.
species known in the 19th
century. About 500,000
A group of individuals of the same species in a given 25 are known today.
location constitutes a population. The populations of
different organisms that share an area and occupy it at
the same time make up a community. The community,
The approximate number
in contact with the nonliving parts of the environment,
forms an ecosystem. All ecosystems taken together of chemical elements (out
comprise the biosphere. of a total of 92 natural
elements) that are used
by living things.
E
R
INDIVIDUALPOPULATIONCOMMUNITY ECOSYSTEM HE
P
S
O
I
B
Relationships Biodiversity Recycling
Milestones in Ecology
Ecology places a special emphasis on the The total number of species of living Like energy, nutrients and other
Although ecology is usually thought of as one of the newest branches of science, it is
complex relationships that living things things that inhabit the planet is substances pass through the
also one of the oldest. From the time they were nomadic hunters, people had to be
establish within their own species (intraspecific unknown. The variety of ways in which they living organisms in an ecosystem. In
concerned about the relationships between living things.
relationships) and between different species in a live, however, never ceases to amaze. This this case, substances are used over and
community (interspecific relationships). diversity can play an important role in the over, creating a cycle.
4th Century BC19th Century AD1866192619351979
stability of ecosystems.
The ants in the The leafy sea dragon (Phycodurus Earthworms, roundworms, bacteria, and
photograph hunt eques), an exotic relative of sea fungi make up a group of organisms known Aristotle and his Naturalists embark on great Ernst Haeckel coins Vladimir Vernadsky Arthur Tansley coins the James Lovelock
together (an horses, essentially disappears as it as decomposers. They feed on waste disciple Theophrastus maritime expeditions. the term “ecology” publishes The Biosphere. term “ecosystem” to refer publishes Gaia:
intraspecific approaches algae; it is hidden by its products and on the remains of dead plants produce the first Humboldt describes the (oekologie, in In this book he de- to the interaction between A New Vision
relationship) and perfect camouflage. and animals. They return nutrients back to writings about the relationship between living German) and scribes the concept of biocenosis (a group of About Life on Earth.
can therefore the soil, where they are reused by plants. relationships organisms and climate for consequently lends the biosphere and dis- living beings) and the The author argues that
capture prey that between organisms. the first time. recognition to the cusses the principal biotope (the environment the living and nonliving
are much larger Möbius proposes the term new discipline. biogeochemical cycles. in which they live). elements of the planet
than any one of the biocenosis to refer to the interact to form a
ants. The concept that the various unique organism that
relationship between species in a community are regulates itself to
the ants and the not independent of one maintain conditions that
worm (predation) another. Darwin publishes his are favorable to life.
is interspecific. theory of evolution in On the
Origin of Species. Warming
lays the foundation for a new
discipline when he includes a
consideration of abiotic
(nonliving) factors in the
study of communities.
10 ECOLOGY: INTRODUCTION AND BACKGROUND ECOLOGY 11
The Five Kingdoms
1.5 million 3 PROTISTA (PROTIST) Hierarchical Order
Unicellular and multicellular eukaryotic organisms that are
Organisms are classified into a system in which some
not part of any other kingdom of life. They include
I The number of species that have euglenoids, dinoflagellates, fungi, and other eukaryotic groups are placed within larger groups. For example,
n order to begin to understand nature, a system must be created to organize the seemingly endless been described by science. It might microorganisms. (In a eukaryote, the cell’s genetic domains are divided into kingdoms, which in turn are divided
represent only 5% of all the species material is organized into into phyla. Phyla are divided into subphyla and so forth
array of organisms. This issue, which has been the topic of many proposals, debates, and disputes in the world. chromosomes, and a down to the level of species.
nuclear membrane
among naturalists for centuries, has yet to be completely resolved. Nevertheless, a few methods for
separates it
An Example: The Classification
classifying organisms have been established that pay attention to the morphological characteristics from the rest
of the cell.) of Human Beings
(or physical features) of different groups and their evolutionary history. Both classification methods
Paramecium Domain: Eukarya (organisms whose
are used to determine the relationships between organisms. 2 PLANTAE (PLANTS) sonneborni cells contain linear DNA, a
Magnified cytoskeleton, a nuclear
Multicellular organisms. Their cells
1,500 times. membrane, and other
are eukaryotic, and they have a
internal membranes).
cell wall. Using a pigment called
Universal Names Classifying Life chlorophyll, they capture energy Homo
from sunlight and use it to Kingdom: Animalia (multicellular neanderthalensis
produce and store their food. organisms that ingest
There are two types of names for organisms. The At one time, all living things their food).
common name is the one most people use, but common were formally classified into
names can vary from one region to another. The scientific two kingdoms, animal and plant. 4 PROKARYOTA (PROKARYOTE) Phylum: Chordata (animals that
name, derived from Latin, allows any researcher in the world Today the most widely accepted at some time in their life
Unicellular organisms. They are cycle have a hollow
to refer to a specific organism without the possibility of classification divides organisms
prokaryotes—that is, they have relatively dorsal nerve cord and
confusing one species with another. into five kingdoms, although a few
primitive cells. In prokaryotes, genetic pharyngeal gill slits).
alternative systems have been material is not surrounded by a nuclear
proposed and are under discussion. membrane (as it is in eukaryotes); it is
Subphylum: Vertebrata (animals that
instead inside a cytoplasmic compartment. have a nerve cord enclosed Homo erectus
The scientific name in a vertebral column).
of the great white
shark is Superclass: Tetrapoda (land animals
Carcharodon with four limbs).
carcharias. 1 ANIMALIA
(ANIMALS) Class: Mammalia (the young are
nourished with milk from
Multicellular mammary glands; the skin
organisms. Their cells has fur; they are
are eukaryotic and do warm-blooded). Homo sapiens
Amazon river not have a cell wall.
dolphin, pink dolphin, In general, they are Order: Primates (they have fingers and flat nails, a poor
cboomtom, aonnd n baumfeeos agriveen athbeleir toow mno pvoew uenrd.er Colony of Escherichia coli saenncsees toofr ss mdiedl)l,. and arboreal habits—or at least their
Each bacterium is about 100 times
to a single animal:
smaller than the thickness of a human
Inia geoffrensis. Family: Hominidae (bipedal and flat faced, with frontal
hair. These bacteria cause various
vision and color vision).
human diseases, such as salmonella.
Genus: Homo (communicates by means of a language). Above,
the skulls of three species of the genus Homo are shown.
5 FUNGI (FUNGUS) Species: Homo sapiens (have a prominent chin, little body
hair, and a high forehead).
Eukaryotic organisms. Traditionally, fungi
were included in the plant kingdom, but
they now constitute their own group. A NEW CLASSIFICATION
One of their characteristics is that they
form spores. Their cellular structure is The best way of classifying organisms continues to be debated. A
very different from that of plants. new category that has been proposed—the domain—lies above the
level of kingdoms. According to this classification scheme, there
BINOMIAL NOMENCLATURE are three domains (two for prokaryotes and one for eukaryotes),
which in turn are divided into kingdoms.
By convention, scientific names are generally Latin
words; they are written in italics.
Determining Kinship
Inia geoffrensis
Through the study of evolution, it is possible to
determine the relatedness and common ancestry of
The first word is the The second word
organisms that look very different.
genus, and its initial is a qualifier, and together
letter is always with the first word it
capitalized. indicates the species. Homologous Analogous
Structures Structures
34
They can be equivalent structures Although these structures
(such as the wings of a bat and appear to be similar or equivalent,
the wings of a bird) or different a careful analysis will show that The arm of a human being The wing of a bird and that of an insect, in contrast,
The approximate number of phyla into which the structures (such as the wing of a they have independent origins (such and the wing of a bird are homologous are analogous structures. They do not have a
animal kingdom is divided. The mollusk phylum bird and the arm of a human). as the wing of a bird and the wing structures. Even though they are different, common origin; however, each represents a similar
alone (which includes snails, octopuses, and Nevertheless, they have a of an insect). They are simply the they have a common origin. adaptive strategy—in this case the ability to fly.
common origin and thus denote result of similar adaptations by
clams) has about 90,000 species. a degree of kinship. organisms to a given environment. Although they are different, birds and humans are more closely related
than birds and insects.
12 ECOLOGY: INTRODUCTION AND BACKGROUND ECOLOGY 13
The Soil
Properties 170
A Because of their nature, soils have a variety of physical and
TEXTURE
ny study about nature needs to consider the importance of soil. Soil provides the surface upon chemical properties. The following are the most important: The number of colors in
Using a magnifying glass or microscope, it is possible to see that the which soils can appear.
which terrestrial organisms carry out their existence, and it is typically the first and foremost
COLOR soil is made up of countless particles of various sizes. This characteristic
source of nutrients in an ecosystem. Not all soils are the same, however, nor do they One of the most useful and readily apparent properties for icsa epxatcrietym feolyr aimerpaotriotann, ta nbde citasu saeb iiltit dye ttoe rhmolidn ews attheer .soil’s porosity, its 100
have the same properties. An effort toward understanding the soil will yield identifying soil classes is their color.
Soil particles are classified by size. This triangular table 90 10
surprising details about the world that exists under our feet. Black
can be used to identify
Black soil is generally associated soil textures according 80 20
500 with a high content of organic Sand to the soil’s physical
One Name, Many Horizons years mIna gteerniearl aaln idt ihsa vse gryo ofder sttilreu.cture. composition. 6070 Clay 3040Percenta
pina sitssa fgtBoeher emolo fsaw tttri imutohcneet—.u sTrmuoerg,i fnceaeotchrmeae lpor ,tof y tsthpihteeieo s s,ng oc,ri lolai muhnnodadr tti,ez ht,oi hconekrs gn sleaioesni lsiu s iposm foo snwr tgshhaoiancltihid zl eidrvdoee pc inikent n (oidbt ,le oadaynnre odmrc satk h(n)h.eyo fraizcotnosr)s, Ttfeohr efto itlreimm s eoa i rll ea1qy iuenircr heod f oRRwmxeeioitdddihs es twsou.i ralIe rti sm ai snt ycdupl isimisuc aaalolltllweyys ar iwinscs hifote hcirn itla oiitlrwieotdyn. Percentage of cla3y04050SSlcoacalanlanamdydyyy lColaamy ScillaSctyyillatyy506g0e o7f s0ilt
(2.4 cm) thick. 20 Loam 80
Silt Sandy Silt
Loamy loam
10 loam 90
sand
1 A Horizon Sand Silt
Yellow 90 80 70 60 50 40 30 20 10
This is the top layer of soil, where humus
accumulates. Humus is formed from organic Yellow soil tends to have Percentage of sand
average or low fertility.
material mixed with the mineral components
of the soil, and it supports a rich variety of Humus Water Air
microscopic organisms. When it rains, water An average volume of soil is 25% 25%
dissolves some of the components of the A primarily composed of mineral
horizon and carries them into the layer below. particles, air, and water and is
Brown Clay only 5% organic material.
Brown soil has little organic
2 B Horizon material, and its fertility Organic material 5%
is variable.
This layer has more clay and is rich in Composed of
minerals, especially iron oxides and lime. Organisms 10%
It receives material from both the A Each horizon
horizon and the C horizon. can be divided White Roots 10%
into layers and White soil is associated with Humus 80% Mineral
subhorizons, particles
light-colored minerals (such as
depending on 45%
3 C Horizon calcite, gypsum, silicates, and
the soil’s salts). It sometimes indicates ACIDITY
Although its characteristics are similar particular soil removal.
to the B horizon, this layer contains characteristics. The acidity or alkalinity of the soil is another extremely important
characteristic. It is measured chemically.
fragments of bedrock that have not been
weathered like those in the B horizon.
Gray 0 7 14
A gray soil is likely one that
Acid Neutral Alkaline
was saturated with water and in
4 R Horizon which there was bacterial Soils with a pH of 7 are neutral. Those with a pH less than 7 are acidic, and those with a pH greater than 7 are
activity in the absence of oxygen. alkaline. Typically, agricultural soils are slightly acidic, with a pH between 5.5 and 6.5.
Also known as bedrock, or consolidated
rock, it is the solid layer upon which the
rest of the soil rests. It slowly contributes
mineral material to the layers above it.
Arthropods
From Rock to Soil Arthropods
Nematodes
The formation of the soil is a long process that normally takes thousands of Miniature Universe
years. Some soils in India, Africa, and Australia are more than two million
Birds
years old. The process begins with the interaction between the atmosphere and In the soil—within the humus and
solid rock; then a biological component is added. among the remains of dead plants
Plants
and animals—there exists a universe of Nematodes
SUNSHINE RAIN HUMUS microorganisms that take care of
decomposing these materials into simple Fungi
organic compounds and returning them
Mammals
to the soil. Nematodes
one billion Bacteria Protozoa
Organic material
1 Solid rock exposed to the atmosphere 2 Organic material filters into the cracks 3 Organic material, together with minerals 4 The soil has formed and begins to
begins to weather and erode. and helps disintegrate the rock. from the rock, begin to form a layer of develop further. The growth of The number of microorganisms that can live First Second Third Fourth Fifth
humus. The soil horizons become defined. vegetation deepens the humus layer. in 35 cubic feet (1 cubic meter) of fertile soil. trophic level trophic level trophic level trophic level trophic level
