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ScienceScienceLearner’s Module

Unit 4 – Module 1

Department of EducationRepublic of the Philippines

This instructional material was collaborativelydeveloped and reviewed by educators from public and privateschools, colleges, and/or universities. We encourage teachers

and other education stakeholders to email their feedback,comments, and recommendations to the Department ofEducation at [email protected].

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mailto:[email protected]:[email protected]

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Science – Grade 8Learner’s Moduleirst !dition" #$1%&S'() *+8,*+1,***$,+#,+

-eublic /ct 8#*%" section 1+0 states that !o copyright shall subsist in anywork of the "overnment of the #hilippines. $owever, prior approval of thegovernment agency or office wherein the work is created shall be necessary for e%ploitation of such work for profit. &uch agency or office may, among other things,impose as a condition the payment of royalties.

'orrowed materials (i.e., songs, stories, poems, pictures, photos, brandnames, trademarks, etc.) included in this book are owned by their respectivecopyright holders. Every effort has been e%erted to locate and seek permission touse these materials from their respective copyright owners. The publisher andauthors do not represent nor claim ownership over them.

#ublished by the Department of Education&ecretary 'r. *rmin *. +uistro &-ndersecretary olanda &. 0ui1ano, #h.D.

eveloment 2eam of t3e Learner’s Module

/ut3ors) #ia -. -ampo, 2ay 3. -have4, 2aria $elen D.$. -atalan, #h.D.,+eticia 5. -atris, #h.D., 2arlene '. erido, #h.D., 6an 7endrich -. ontanilla,#h.D., 8ac9ueline 3ose 2. "utierre4, &hirley 3. 8usayan, 2ichael *nthony '.

2antala, -erilina 2. 2aramag, 2arie #a4 E. 2orales, #h.D., Eligio -. :bille,8r., Digna #aningbatan, "enevieve aye #asamonte, 2a. Dulcelina :.&ebastian, 3olando 2. Tan, and 3odolfo &. Treyes, #h.D.

-evieers) Ernelea #. -ao, #h.D., 8osefina +l. #abellon, #h.D., 2a. -ristinaD. #adolina, #h.D., 3isa +. 3eyes, #h.D., and 2erle -. Tan, #h.D.

&llustrators *lvin 8. Encarnacion, 2a. +aura 5. "inoy, 3i4aldo 3amoncito &.&aliva, and *ndrew . Torres

Layout /rtist -ecile !. &ales

eartment of !ducation,&nstructional Materials 5ouncil Secretariat 6e!d,&M5S7

:ffice *ddress ;nd loor Dorm ", #hilsports -omple%2eralco *venue, #asig -ity#hilippines >

Telefa% (>;) =?AB or =?AC;

EAmail *ddress [email protected]

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TABLE OF CONTENTS

nit !" Li#in$ Thin$s and Their En#ironment

Page

%odule &' Biodi#ersit( . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Levels of Biodiversity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 2

Activity 1: What’s in a name? . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . 2

Classifying and Naming rganisms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . !

Archaea "omain: #ingdom Archae$acteria. . . . . . . . . . . . . . . . . . . . . . . . . . . %

Bacteria "omain: #ingdom &'$acteria. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . (

Activity 2: )o* do $acteria in yog'rt loo+ li+e? . . . . . . . . . .. . . . . . . . ,

Protists. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 1-

'ngi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . 1% /he Plant #ingdom. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . 1(Nonvasc'lar Plants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . 10asc'lar Plants

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,ymnos3erms

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Angios3erms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . 2-5m3ortance of Angios3erms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . 22)armf'l Plants

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 /he Animal #ingdom

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2!63onges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . 2!Cnidarians

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

lat*orms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2%

8o'nd*orms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2%

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6egmented Worms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2(

9oll's+s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. 20&chinoderms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . 2,Arthro3ods

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Activity !: What can yo' do to 3revent deng'e? . . . . . . . . .. . . . . . . . !-

Chordates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. !2erte$rates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . !2

ishes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . !2Am3hi$ians . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . !78e3tiles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . !7Birds

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . !%

9ammals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. !0Lo* and )igh Biodiversity

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . !,Activity 7: What is the im3ortance of $iodiversity to

ecosystems? . . !4Protecting and Conserving Biodiversity

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71Activity %: 5 create the f't're . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . 71

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UNIT 4

Living Things and Their

Environment

Module 1

Biodiversity

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Unit 4

MODULE

BIODIVERSITY

Overview

rom "rades ? to C you have studied some of the different organisms and

their easily observable characteristics. ou learned about those organisms that youfind 1ust around you and other places in the country. ou were taught that organisms

form the biotic component of an ecosystem. ou were introduced to the cells that

differ in plants and animals. 6n addition, you learned about organisms other than

plants and animals. &ome of these consist only of a single cell while others have

many. ou may also had a chance to look at organisms that are so small and can be

seen only with the microscope.

This module will introduce you to the concept of biodiversity" specifically the

variety of organisms living on Earth. This will discuss how they are classified and

named. 6t will also show the similarities and differences of these organisms. 6t willdescribe the different groups to which these organisms belong. 6t will let you discover

uses of some not 1ust as food but also in medicine, agriculture, industries and the

ecosystems where they are present. 6n addition, you will know about the harmful

effects of some to other organisms.

The module will further show you the advantages of high biodiversity over low

biodiversity. 6t will also help you recogni4e the value of biodiversity in your

community. 2ost importantly, this hopes to encourage you to start or continue

protecting and conserving your communitys biodiversity for future generations.

1

Suested time allotment) + to 8 3ours

Why is biodiversity important

What human activities destroy or endanger the e%istence of rare and

economically important species

What human activities help protect and conserve rare and

economically important species

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Levels of Biodiversity

'iodiversity is coined from the words, biological diversity. sually, scientists

would refer to three levels of biodiversity namely different kinds of organisms

(secies diversity), genetic information that organisms contain (enetic diversity)and different kinds of places where organisms live and the interconnections that bind

these organisms together (ecosystem diversity). 6f you recall, you have learned

about ecosystem diversity in the lower grades. ou will know more about genetic

diversity in "rade F.

&pecies diversity consists of the large number and all different kinds, shapes,

colors and si4es of organisms that inhabit the Earth. 6t includes the smallest and the

simplest bacterium (pl. bacteria) to the comple%, bigger, brightly colored flower or

fish. *dd to this the carabao, the tallest acacia, the biggest elephant and a human

like you. These organisms are found in various places from the soil, to the rivers,oceans, forests, salty or hot places, in short in every corner of the Earth. &ome of

them even live in your body. *t present, more than a million organisms have been

identified and named while many more are being discovered every year. 8ust

recently, foreign and local researchers have found that diversity of reptiles and

amphibians in the !orthern #hilippines is even greater than what has been known

and identified.

6f there are a lot more of the organisms in the world than you can count, how

will you be able to know about them Does an organism you see in your place, for

e%ample, have the same name in another place Do organisms have to be

classified Why Try the following activity.

Activity 1

What’s in a name?

Objectives:

*fter performing this activity, you should be able to

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pencil or ballpensheet of paper

!

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Procedure:

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organisms were only grouped into eukaryotes and rokaryotes. 3emember in your

previous year, you knew about the nucleus in cells that contain D!* in chromosomes

having a role in heredity. 6n eukaryotes, these materials are enclosed in a membrane

while in prokaryotes they are not. 2ost prokaryotes are tiny and unicellular, thus, are

referred to as microoranisms. * lot of eukaryotes are multicellular, thus, are larger

in si4e because of the greater number of cells their bodies contain.

3ecently, prokaryotes have been divided into two domains, namely /rc3aea

and 'acteria. The eukaryote group was retained and now consists the third domain

(!ukarya) that includes protists, fungi, plants and animals. Table < shows an e%ample

of how organisms are classified.

Table

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This way of naming organisms is referred to as the binomial system of

classification. *lso take note that scientific names are in the +atin language and are

italici4ed.

ou should know, however, that researchers may differ in classifying

organisms. 6t is important to bear in my mind that with further researches and

discoveries this system of classification may change as more information are gatheredabout organisms found all over the Earth.

Early studies of organisms resulted to only the twoAkingdom classification

system. +ater, with the invention of the microscope and with more evidences gathered

about different forms of life, various scientists proposed three, to four, then, five and

later to si% or even eightAkingdom classification. $ere, the si%Akingdom classification

will be used namely *rchaebacteria, Eubacteria, #rotist, ungi, #lant, and *nimal

kingdoms.

Archaea Domain: Kingdom Archaebacteria

:rganisms that belong to this kingdom are all microscopic. They live in

various places, some even in the most severe environments. Met3anoens,

3alo3iles and t3ermo3iles are e%amples of archaebacteria.

Do you know that methanogens can survive in places where there is no

o%ygen &ome members of this group inhabit digestive tracts of animals and ponds

where animal, human and domestic wastes are treated (igure

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6f you live in areas which make salt, have you observed the orange or yellow

color in salt ponds This is due to the presence of halophiles. These archaebacteria

are adapted to very salty environments. E%amples are Haloccocus dombrowski and

Halobacterium salinarum.

0F. 3ead about the Dead &ea and the "reat &alt +ake of tah, &*. What dothese have in common

igure ; below are e%amples of thermophiles. This group of archaebacteria

can live in places with high temperature. These areas include volcanic hot springs

with temperatures from G> to °- come out. Thermophiles turn

hydrogen sulfide ($;&) released from these openings to food for other organisms and

in turn are provided essential nutrients by the former.

(a) (b)

6o'rce: Phili33ines. "e3artment of &d'cation. 2--4;. 6cience and /echnology 55. /e

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present in raw or spoiled foodJ others live in or on other organisms including your

body. ou must have known that they also cause disease and harm to other

organisms. 'ut most importantly, bacteria have a variety of uses for the environment

and for humans.

Ada3ted from: Phili33ines. "e3artment of &d'cation. 2--4;. 6cience and /echnology 55. /e

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'acteria also cause diseases in animals. Bacillus anthracis is responsible for

the disease called anthra%. The bacterium is found in the soil and can survive for

many years. The disease affects animals like cows and carabaos but can be

transmitted to humans. &kin anthra% occurs in the #hilippines through contact with

animal tissues or their products. 6nhalation and intestinal anthra% caused by inhaling

spores and eating of contaminated or undercooked meat, respectively, are moredeadly. 6t is strongly advised to refrain from eating meat of dead animals suspected

to have died of anthra%. 6n the early ;>>>s there was a worldwide threat of using

anthra% spores to kill people in what is termed as HbiologicalI warfare.

0

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Materials Needed:

; droppers diluted yogurtcoverslip glass slidemicroscope methylene blue

Procedure:

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6o'rce: Phili33ines. "e3artment of &d'cation. 2--4;. 6cienceand /echnology 55. /e

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movement, those with cilia, and those with limited movement. :thers which are

nonmotile and form spores belong to the soro;oan group. 2embers of this group

are all parasitic.

#hototrophs are like plants in that they have chlorophyll. This group includes

the alae, dinoflaellates, and eulenoids.

*lgae may be green, golden, brown or red. The chlorophyll in green algae is

not masked in contrast to the other members of the group. The carbohydrate that

green algae produce is stored as starch. They grow on wet, humid rocks or bark of

trees, in nonAflowing canals, in seas, freshwater bodies and even polluted waterways.

Green alae differ in si4e and shape. &ome are unicellularJ others form colonies,

sheets, filaments, tubes and ribbons (igure B). &ome green algae are edible. The

marine green alga &aulerpa lentilli'era is eaten fresh as salad.

(a) (b) (c) (d)


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6n one of your trips to the seashore, did you notice something like one of

those shown in igure C 6f your answer is yes, you have seen bron alaeK 2ost

members of this group are marine so you can see them 1ust lying around on the

beach. 'rown pigments mask their chlorophyll.


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Figure 8. Examples of red algae.

3ed algae can change color depending on whether they are e%posed or

hidden from light. When they are e%posed to light, they are bright green in color. 6f

they grow without much light, they are colored red. 2embers of the group consist of

both microscopic and large multicellular organisms. 2ost of them are found in marine

waters.

There are species in the group that help form coral reefs because of their

ability to produce calcium carbonate. Economically, E. muricatum is useful being a

source of agar and carageenan. 6f you are fond of eating gulaman, note that it comes

from agar. Eucheuma farming has become a source of livelihood in certain areas in

-entral 5isayas and 2indanao. +ikewise, (racilaria salicornia (igure G) is an agar

source and edible too.

0;>. Why is light important to algae

2ost members of dinoflagellates live in oceans and seas. They are mostly

unicellular. &ome occur as single organisms, while others form colonies. *n important

dinoflagellate to know is Pyrodinium bahamense var . compressum (igure F). They

are the ones that cause Hred tideI when present in large numbers. During red tide,

people should not eat clams and mussels in the affected areas. This is because these

organisms might have fed on the dinoflagellates which produce to%ins and cause

paralysis of the diaphragm that can lead to death.

Ada3ted from: Phili33ines. "e3artment of &d'cation. 2--4;. 6cience and /echnology 55. /e

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These temporary e%tensions are formed when changes in the cytoplasmic

concentration occur within the cell. This change causes the cell membrane to contract

and enable the organism to make a creeping movement. #seudopods may form as

they are needed.

0;;. -ompare pseudopods of foraminiferans, radiolarians and amoeba.


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diarrhea, while ". (ambiense is responsible for "ambian sleeping sickness.

"richonympha (igure

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ou knew earlier that plants belong to the eukaryote group. They are

multicellular and because they have chlorophyll, they can make their own food.

#lants consist of two big groups those which do not have tissues to transport water

and food (nonvascular ) and those that have this transport system (vascular ).

Nonvascular Plants

$ave you noticed green patches attached to stones or cement walls

especially during the rainy season or in moist, wet and shady areas

+iverworts, mosses and hornworts (igure

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0;F. Why do you think nonvascular plants cannot grow very large or tall

Vascular Plants

rom studying waterAdwelling organisms, you will now deal with ferns which

thrive on land with true roots, stems and leaves. erns also reproduce by spores.

2ore than F>> species of ferns can be found in moist, shaded and mountainous

areas in the country. They e%hibit diversity in si4e from a few millimeters to about

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&yathea sp. (tree fern) (c)

0?

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They also supply pulp to paperAproducing factories. :ther species provide resin,

used in making perfumes and varnishes. #ine cones are popular -hristmas

decoration items.

0?. $ow would uncontrolled cutting of pine trees, for e%ample, affect the forest

ecosystem

Angiosperms

ou are most familiar with members of this group as you may have played

with their flowers even at an early age. 6n the earlier grades, you have learned how

varied they are in terms of parts and habitat. ou also studied about what parts are

involved in reproduction and ways by which they reproduce. They are also called

flowering plants since flowers, as well as fruits, are involved in their reproduction and

development.

*ngiosperms can be classified according to their lifespan. *nnuals live for a

year or one growing season and die like rice and corn. 'iennials develop roots,

stems and leaves during the first year, produce seeds on the second year, then die.

#erennials live for many years, usually producing woody stems like tsitsirika,

bamboo, and trees.

+eaves of angiosperms also differ in their arrangement in the stem. &tudy

igure

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(umamela and mango are dicots. :ther differences among the two are e%hibited in

characteristics of some of their parts as shown in igure

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ou can observe several flowers from different plants and you may see other

differences or similarities among them.

27

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&mortance of /nioserms

+ook around you. Think of what you have eaten or what you have used

earlier. Were there any from this group of plants mentioned that you have eaten, or

in any way used

*ngiosperms of importance worth mentioning are ilipinos staple food rice

for most of us, corn in some areasJ vegetables like camote tops, malunggay

cabbage, carrots, saluyot and s9uash.

0?G. 2ake a list of the uses of coconut that you know.

2any of our agricultural products, both fresh and processed are e%ported.

E%amples are banana from Davao, mango from "uimaras, coffee from various

provinces, pineapple from 'ukidnon and tobacco from provinces in !orthern +u4on.

urniture made from rattan are also sold to various countries abroad. &ugar canefrom different provinces is also another grown for e%port.

2any angiosperms have been developed to prevent and cure some diseases.

Lagundi , sambong , ampalaya, and banaba to name a few are now commercially

available for specific ailments.

0?F. Describe how birds, butterflies and spiders benefit from members of the

angiosperms.

0>. What is the greatest contribution of plants to living things on Earth

Harmful Plants

&ome plants can be harmful to animals, humans, and even to other plants.

-are must be taken that cows and other livestock should not gra4e in areas where

sorghum grow. 6t is known to cause cyanide poisoning in livestock as young leaves

contain a poisonous substance.

atropha curcas (tubaAtuba/tubang bakod) is popular due to its being an

alternative source of bioAfuel. *lthough known to have medicinal properties, its seed

is poisonous. The fruits which are usually eaten by children cause stomach pain,

burning sensation in the throat and vomiting. Manihot esculenta (cassava) if boiled

with its bark on it can be poisonous. The bark contains hydrocyanic acid. 6t is advised

that during cooking, the pot cover should be removed for the cyanogas to escape. *

word of caution do not eat any part of a plant which you are not familiar with.

Echinochloa crus#galli (dawaAdawa) and /igitaria sanguinalis (sakaAsaka) are

weeds which are alternative hosts to abaca and corn mosaic viruses.

0

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The Animal Kingdom

What can you remember about the characteristics of animal cells $ow do

animals differ in si4e, shape or habitat $ow do they respond to their environment

*nimals differ in si4e and shape. 6n "rade C, you learned that small ones

have few cells while big ones can have up to trillionsK &ome animals can live inside

other animals. :thers are found in fresh or marine waters and some in every habitat

on land. They reproduce either se%ually or ase%ually.

Despite their differences, animals share basic characteristics. 'y now you

must have known that this group are eukaryotic and multicellular. &ome get

nourishment from other animals, others eat plants while others feed on protists. ou

knew that animal cells have no cell walls. 'ut they have cells involved in movement

though some species are nonmotile. *nimals also have cells that transmit messages

throughout their body.

0;. 6n your observation, how are animals distinguished from the other groups as to

their reaction to stimuli

*nimals consist of two ma1or groups, the invertebrates and vertebrates.

6nvertebrates lack backbone which is present in vertebrates. 6n this section, you will

discover the diverse characteristics, uses and roles in the environment of nine in

about thirty five animal phyla.

Sponges

&ponges, the simplest animals, belong to #hylum #orifera. They live in

shallow and deep oceans. The young of sponges are motile, while adults are

attached to solid materials like rocks. The body of a hard sponge is supported by a

HskeletonI called sicules, made of either glasslike silica or calcium carbonate. *

network of protein fibers supports soft sponges. This is the one used for bathing and

washing.

2(

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(Source: Philippines. Department of Education. (2009). Science and Technology II.

Textbook (Rev. ed.). Pasig City: Instructional Materials Development Corporation. p.285).

Figure 18. Structure of a sponge showing how water and food and waste

materials move in and out of its body, respectively.

Water and food enter through the pores into the sponge body (igure

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$ydra represent freshwater cnidarians. :ther marine cnidarians are shown in

igure

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&ome roundworms are freeAliving while others are parasites of animals and plants.

The freeAliving ones are important as they are decomposers in the soil in both marine

and freshwaters. * lot of them are found in decaying organic matter. #arasitic

roundworms can be found in moist tissues of plants and animals. $eartworms for

e%ample can infect dogs and cats. $umans can be infected with parasitic

roundworms such as trichina worms, hookworms and the more common pinwormsand !scaris (igure ;>) afflicting children.


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segment contains most of the internal structures of these systems. "as e%change

only occurs by diffusion through their skin. This is why earthworms need to be in

moist places like under rocks or stay buried in the soil. *s they feed and burrow

through the soil, they get nutrients and eliminate wastes (castings) through the anus.

6n this way they aerate the soil and the castings serve as fertili4er.

+eeches are bloodAsucking annelids. They have suckers in both ends of their

bodies that are also used to attach themselves to their hosts. They secrete an antiA

clotting chemical that has been used in medicine.

Mollusks

2ollusks (#hylum 2ollusca) are softAbodied invertebrates with most of them

covered by a shell. They have comple% respiratory, reproductive, circulatory,

digestive and e%cretory systems functioning together for their survival. The mollusksbody has three parts a muscular foot for locomotion, a mantle that produces the

shell, and the visceral mass that contains their internal organs. 2ollusks consist of

three classes the Gastroods" 'ivalves and 5e3aloods.

0=. &tudy igure ;>F). Science and "echnology 00. "e-tbook (3ev. ed.). #asig -ity6nstructional 2aterials Development -orporation. p. ;F

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The cephalopod group include the s9uid and cuttlefish with internal skeleton.

The chambered nautilus has e%ternal skeleton while the octopus is shellAless. *ll

cephalopods are described as the most active mollusks, moving very fast using arms

and tentacles in catching prey.

0C. 6nto which group would you classify halaan the giant *frican snail"ridacna

(taklobo)

2any mollusk species are utili4ed as food like tahong (mussels), talaba

(oyster), halaan (clam), scallops, and kuhol or suso to name some. :ther species

are made into decorative items.

"olden kuhol, however, has become a pest to rice and other crops. They eat

a lot of plant leaves and reproduce rapidly. The giant *frican snail !chatina 'ulica was

found to be an intermediate host to a rat lungworm that causes meningitis.

Echinoderms

ou can be fascinated by the starAshaped sea star or the spineLstudded sea

urchin and the appearance of the sand dollar. *long with the brittle star and the sea

cucumber, they belong to #hylum Echinodermata. *ll echinoderms are found in a

marine environment. &ea lily, another echinoderm, is rooted in the sand at the bottom

of the sea, while sea cucumber burrows in mud of deep or shallow waters.

#arts of most echinoderms radiate from the center of the body. They alsohave spines which are e%tensions made of hard calcium. nder the skin, these form

an internal skeleton called the endoskeleton.

&ea stars have the ability to regenerate. * cut arm can easily regrow into a

new sea star.

ni9ue to echinoderms is the presence of the waterAfilled tubes that spread

out to form the tube feet (igure ;;). Tube feet are used for getting food, moving

around and gas e%change.

!1

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(Source: #hilippines. Department of Education. (;>>F). Science and "echnology 00. "e-tbook (3ev. ed.). #asig -ity 6nstructional 2aterials Development -orporation. p. ;F.)

Figure 22. Sea star showing (a) arms radiating from the center of the

body, (b) spines, and (c) tube feet.

Echinoderm species which are edible include the sea urchin and sea

cucumber. Holothuria edulis a sea cucumber, is dried and used as ingredient for

chopsuey and soups.

3emember the role of coral reefs in the environment &ea urchins are

important to coral reefs because they consume algae that otherwise overgrow and

can kill the corals. 6n contrast, the sea star, crown of thorns, are predators of coral

polyps posing a threat to the e%istence of the reefs.

Arthropods

$ave you observed what grasshoppers, spiders, crabs and centipedes have

in common 6f you take a look at each of these you will notice that they have

1ointed legs. These animals belong to #hylum *rthropoda. The group is considered

the most successful of all animal phyla as they are present in almost all types of

habitats. There are arthropods that walk or crawl, some can fly, while others swim

in salty and freshwaters.

3ecall in "rade =, you learned that arthropods have an e

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may be used for avoiding predators, getting food, walking or swimming.

5rustaceans form one group of arthropods which includes water fleas, crabs,

shrimps, lobsters and barnacles. They have hard e%oskeletons and have mandible

to bite and grind food. *ll crustaceans live in water with the e%ception of the pill bug.

ou see it in the soil as the small creature that rolls into a tiny ball when disturbed.

*9uatic crustaceans have gills for breathing. 2any crustaceans are food to humans.The small ones are eaten by fishes and even whales.

/rac3nids have two body sections, most with four pairs of legs and

mouthparts called c3elicerae and edials. They use book luns to respire.

&piders with thin and fle%ible e%oskeleton are the largest members of the group.

2ites and ticks are parasitic arachnids. They cause itching to some mammals,

including humans. &corpions have a poisonous sting. The horsehoe crab, a close

relative of arachnids, is considered the oldest living arthropod.

Milleedes and centiedes, close relatives of insects have long, wormlikesegmented bodies. They have a pair of antenna and each segment bear a pair or two

legs. These animals live in the soil, under rocks or rotting logs and leaves. 2illipedes

have two pairs of legs per segment and roll up when disturbed. They feed on

decaying matter. -entipedes have a pair of legs in a segment. They have venomA

containing claws and feed on earthworms, even other arthropods and small animals.

&nsects form the largest group among arthropods. They have three body

sections, three pairs of legs, a pair of antenna and one to two pairs of wings. 6nsects

are more adapted for flying and have tracheal tubes for respiration. They are present

in great numbers in all kinds of environments e%cept in marine waters. E%oskeletonof insects as that of a fly is thin. 6nsects are also successful animals because they

reproduce rapidly. Dragonflies, grasshoppers, aphids, and butterfies are some

e%amples of insects.

0B>. Which arthropod group has no antenna

0B

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Procedure:

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0BG. 6nto what group of arthropods would you classify the mos9uito and why

Chordates

*nimals belonging to #hylum -hordata have four characteristics that are

present in any of the stages in their life cycle. These are the notoc3ord, t3e dorsal3ollo nerve cord, ill slits and a ost,anal tail. 6n many chordates, the notochord

later becomes the backbone. $umans being a member of the chordate group have

the notochord, tail and gill slits only in the embryo stage.

$owever, there are lower chordates that do not have a backbone. E%amples

are the tunicates and lancelets. The adult tunicates have only the gill slits present

but the larva stages have all the four features. Tunicates attach to solid materials like

rocks or coral reefs. They are filter feeders, taking in food particles suspended in

water.

+ancelets have the four chordate characteristics present in the adult stage.

They live in the sandy ocean bottom. They are also suspension feeders. +ancelets

move in a fishlike motion using the muscles on both sides of their body.

Vertebrates

2ost vertebrates are sea and land dwellers forming the large group of

chordates. The vertebrates notochord is replaced by the backbone or the vertebral

column (vertebra, plu. vertebrae). The nerve cord is enclosed by the pro1ections of

the vertebrae. The protected nerve cord enlarges at the anterior end to develop into

the brain. The tail can be the bone and muscle that animals use for swimming in

a9uatic species. or some vertebrates, the gill slits remain till the adult stage. 6n

others, these are modified into structures for gas e%change.

Fishes

ishes are vertebrates found in salty, fresh, cold or even hot water. 2ost

have scales for protection, paired fins for movement and gills for gas e%change.

ishes may lay eggs to reproduce or give birth to live young. They are cold blooded

because their body temperature changes when environment temperature changes.

-ertain fishes do not have true teeth or may be 1awless as compared to the others.

8awless fishes belong to -lass *gnatha. E%amples are the lampreys and hag

fish. +ampreys, being parasites, have toothAlike structures in their mouth that can

attach to bodies of other fishes and feed on their tissues and blood. The hagfish is

wormlike and use a toothlike tongue to eat dead organisms.

-artilaginous fishes include the rays, skates and sharks. They have a

skeleton made of the soft, fle%ible protein material called cartilage. 2ost cartilaginousfishes are covered with a tough, sandpaperlike skin due to the presence of toothlike

!(

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scales. &kates and rays have winglike fins and move in a gliding motion through the

water. &ome of them eat floating planktons while others feed on invertebrates at the

bottom of seas and oceans.

&harks may feed on small fishes or on floating algae. The whale shark

(%incodon typus), the largest fish, and locally known as butanding is found in marinewaters of -ebu, &orsogon and Dumaguete.

The diverse groups of bony fishes belong to -lass :steichthyes. These are

the fishes that have an endoskeleton made of hard, calcium material called bone.

'ony fishes are more familiar to you like bangus (milkfish), tuna, goldfish, and tilapia.

The nonAfamiliar lungfish breathes through the lungs in addition to having gills also

for respiration. Eels are wormlike fishes. igure ;? shows some of the members of

the bony fishes.

( *dapted from #hilippines. Department of Education. (;>>F). Science and"echnology 00. "e-tbook (3ev. ed.). #asig -ity 6nstructional 2aterialsDevelopment -orporation. p. ?>

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Amphibians

*mphibia means Hdouble lifeI from which amphibians got their name. This

refers to animals that live part in water and part on land. 2ost lay small, shellAless

eggs surrounded by 1ellylike substance in moist places or in water. These hatch into

tadoles with gills and tails. They lose the tail to develop lungs as well as legs and

move to land but close to water or damp habitats. They also have moist skin to help

the lungs for gas e%change while in dry land. *mphibians are divided into three

groups, the caecilians, salamanders, and fro and toads. -eacilians live in water

or bury themselves in moist soil. &alamanders live in forest floors under rocks and

decaying logs.

'oth frogs and toads 1ump. &ome frogs can leap and attach to tree trunks and

branches. Toads are terrestrial and can even survive in hot places or desert. rogs

have smooth skin while toads have rough or warty skin. rogs and toads eat worms,

insects or small animals.

(Ada3ted from: Phili33ines. "e3artment of &d'cation. 2--4;. Science and Technology II. Textbook 8ev. ed.;. Pasig City: 5nstr'ctional 9aterials "evelo3ment Cor3oration. 3. !-2.;

Figure 24. Amphibians include (a) the mud puppy, (b) a tree frog,

(c) caecilian, and (d) toad

0=>. 3efer to igure ;. Which amphibian(s) is/are tailAless

0=

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(&ource #hilippines. Department of Education. (;>>F). Science and "echnology 00. "e-tbook (3ev. ed.). #asig -ity6nstructional 2aterials Development -orporation. p. ?>B.)

Figure 25 Different beaks of birds.

0=;. E%amine the beak of the #hilippine eagle. 6f it is for cutting, what do you thinkdoes this bird eat?

E%amples of birds that do not fly are the kiwi, penguin and ostrich.

0=?. -ompare the legs of amphibians and reptiles with birds that you are familiarwith.

ou often eat chicken during meals or even merienda. :r maybe balut and

salted eggs from ducks are your favouritesK &nakes and big animals also prey on

smaller birds. ou en1oy the rela%ing chirping or singing of some birds and their

varied colors. *lthough certain birds feed on rice or corn grains, they have a role in

dispersing seeds to various places, res'lting to perpetuation of many plant species.

The #hilippine Eagle, which is found only in our country, has been declared

as a critically endangered species. 6t means that there is a possibility that the species

will disappear or be lost. The main reason is the loss of their habitatAA the forests AA

due to logging and their conversion to farmlands.

0=. 6f you live somewhere in eastern +u4on, &amar, +eyte or 2indanao where the#hilippine eagles specifically live, suggest ways to protect their habitat.

7-

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Mammals

2ammals differ from other animals because they have mammary glands that

produce milk to nourish their young and most have hair or fur. They breathe in air,

have fourAchambered hearts and are warmAbloodied. 2ost of them also give birth tolive young and care for them.

The first group of mammals, called monotremes, lay eggs similar to those of

birds. The spiny anteater (echidnas) living in *ustralia, !ew Mealand and !ew

"uinea as well as the duckAbilled platypus are monotremes (igure ;=).

(&ource #hilippines. Department of Education. (;>>F). Science and "echnology 00. "e-tbook (3ev. ed.). #asig -ity 6nstructional 2aterialsDevelopment -orporation. p. ?>=).

Figure 26. Examples of Monotremes.

Marsuials or the pouched mammals also give birth to live young. *fter birth,

the young are kept inside pouches and are nourished with the milk from the

mammary glands within these pouches. &ome marsupials are found in -entral and

&outh *merica. The opossum lives only in !orth *merica. :thers, such as the more

familiar koalas, kangaroos and wombats and flying phalangers, are found in *ustralia

and !ew Mealand.

The eut3erians comprise the largest group of mammals. 7nown as the

placental mammals, they bear fully developed young inside the mothers uterus.

These young are attached to the placenta through which they receive nourishment

until they are born. *fter birth, they continue to be cared for and nourished by milk

from the mammary glands. Table ; presents the different groups of placental

mammals and their representatives.

Table ;. #lacental mammals

=rder 53aracteristics !

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=rder 53aracteristics !>F). Science and "echnology 00. "e-tbook (3ev. ed.). #asig-ity 6nstructional 2aterials Development -orporation. p. ?>C.)

0=B. Which of the eutherians live in water

0==. 6n your observation, how do humans differ from other primates

#rimates are the most highly developed of all animals. They are able to walk

erect, with fingers and toes adapted to grasp or hang on branches and hold things or

manipulate food. They also have a high degree of intelligence. #rimates e%hibit social

behavior like living in organi4ed groups or communities. They take care of orphaned

individuals or even fight with competing groups. &cientists would like to believe that

the care given by females to their young contribute to their ability to survive.

0=C. What characteristics differentiate mammals from other animals

2ammals are present in various places, from the very cold to the warmestregions and in salt waters. 2any live among humans. 2ammals have become an

important part of ecosystems. 6n grasslands, 4ebras eat plants and in turn are killed

and eaten by lions. 6n forests, bats eat insects and compete with monkeys for fruits.

&eeds are then spread for plants to grow in other areas. Wastes of these mammals

serve as fertili4ers to plants. 6n human communities, rats carry bacteria and dogs

virus that cause diseases. 6n farmlands, carabaos work for people, while cows, sheep

and goats provide meat and milk. 3ats destroy crops and compete with humans for

rice grains. 6n whatever way, good or bad, mammals affect the ecosystems where

they live.

ou have 1ust gone through all the different groups of organisms on Earth

known to science at present. ou have learned about their similarities and

differences. The discussions and activities also showed how they are useful to one

another and the whole ecosystem or how some harm others.

Low and High Biodiversity

6n the earlier grades you learned that among different ecosystems, the

rainforest has the highest biodiversity. This means that it has the greatest number of

species living in it. 3ainforests have a high rainfall, thus, have lots of plants in them.This condition provides shelter, water and food to many species that can survive

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drought or disasters as well as competition with other species. This results to a stable

ecosystem with lesser rate of species loss. Tropical rainforests are located in places

near the e9uator, while temperate rainforests are found in the temperate regions.

0=G. 'ased on the discussion above, how will you describe an ecosystem with low

biodiversity

Activity 4

What is the importance of biodiversity to

ecosystems?

Objectives:


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#hoto by 2D &ebastian

Figure 27. A banana plantation.

0C>. Does it have a high or low biodiversity

0C>F). Science and "echnology 00. "e-tbook (3ev. ed.).#asig -ity 6nstructional 2aterials Development -orporation. p. ??F).

Figure 28. A coral reef ecosystem.

0C. What biotic components are present in this ecosystem

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0CB. Describe some relationships and interactions that occur among these bioticcomponents.

0C=. #redict the effect of the presence of many crown of thorns sea star to theecosystem and its biotic components.

0CC. Why is high biodiversity advantageous over low biodiversity

0CG. What is the importance of biodiversity to ecosystems

The !orth #ole and certain deserts are e%amples of ecosystems with low

biodiversity.

0CF. "ive other e%amples of familiar ecosystems with low biodiversity.

Protecting and Conserving Biodiversity

ou have seen that organisms in an ecosystem are interdependent upon each

other for survival and harmonious e%istence. This interdependence among them

demonstrates the importance of biodiversity to an ecosystem. ou must know

however, that as more species are discovered every year, others previously known

and identified have decreased in number or have disappeared. * good way to

remember the causes of species decline is through the acronym :&99=>

$ A $abitat destruction

6 A 6nvasion of introduced species

# A #opulation increase

# A #ollution

: A :vercollection/overharvesting of resources

Think of the biodiversity in your community at present. What would it look like

in the future

6n the following activity, you are going to make a list of conditions that you want

to see in your world in the future. #rioriti4e them, suggest ways and take action tomake them happen.

N Threats to 'iodiversity. 3etrieved from http//www.eAeducation.psu.edu/geog>?>/node/?F

Activity 5

I create the future1

1

*dapted from 0llinois Biodiversity Basics, a biodiversity education program of the 6llinoisDepartment of !atural 3esources, -hicago Wilderness, and the World Wildlife und

7%

http://www.e-education.psu.edu/geog030/node/394http://www.e-education.psu.edu/geog030/node/394

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Objectives:


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=. -ompare your personal pyramid to the pyramid that your group came up with.

0G

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understanding of your communitys biodiversity, the organisms importance to and

interactions with each other. se them wisely and conserve biodiversity. 6t is only

when you understand all of these will you reali4e that you cannot afford to lose any of

these, for all of you and your future, will be affected. H*-T !:W, !: :!E -*! D:

T$6& :3 : !:3 :3 &KI

6n the ne%t module, you will be introduced to more ways by which these

organisms affect and interact with each other as well as with the environment they

live in.

7,

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3eferences and +inks

'ailey, 3. (;>

8 sci lm u4- m1

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