8/3/2019 Chordata

1/28

Phylum ChordataPhylum ChordataTheThe ChordataChordata isis considered,considered, oneone ofof thethe mostmost importantimportant phylaphyla ofof thethe

animalanimal kingdom,kingdom, atat whichwhich thethe manman isis involvedinvolved;; asas wellwell asas hishis domesticdomestic

animalsanimals.. TheThe phylumphylum includesincludes animalsanimals withwith threethree distinguishingdistinguishing

characteristicscharacteristics:: ((11)) aa dorsaldorsal hollowhollow nervenerve cord,cord, whichwhich arisesarises asas anan

infoldinginfolding ofof thethe surfacesurface ectodermectoderm;; ((22)) aa dorsaldorsal longitudinallongitudinal skeletalskeletal rod,rod,

thethe notochord,notochord, locatedlocated beneathbeneath thethe nervenerve cordcord;; andand ((33)) pairedpaired ofof laterallateralopenings,openings, commonlycommonly referredreferred toto asas gillgill cleftsclefts oror slits,slits, throughthrough thethepharyngealpharyngeal wallwall ofof thethe gutgut.. AlthoughAlthough thesethese threethree structuresstructures areare foundfound inin

thethe earlyearly developmentaldevelopmental stagesstages ofof allall chordateschordates andand werewere probablyprobably

characteristiccharacteristic ofof thethe ancestralancestral chordates,chordates, notnot allall persistpersist inin adultsadults.. TheThe

notochordnotochord disappearsdisappears duringduring developmentdevelopment inin mostmost vertebrates,vertebrates, andand onlyonly

thethe hollowhollow nervenerve cordcord andand thethe pharyngealpharyngeal clefts,clefts, oror theirtheir derivativesderivatives

remainremain inin thethe adultadult..

Most of the chordates are vertebrates, but there are two smallMost of the chordates are vertebrates, but there are two small

subphyla of invertebrate chordates, i.e., chordates lacking a vertebralsubphyla of invertebrate chordates, i.e., chordates lacking a vertebral

column or backbone.column or backbone.

8/3/2019 Chordata

2/28

Characteristics of Phylum Chordata:Characteristics of Phylum Chordata:

TheThe followingsfollowings areare thethe generalgeneral characterscharacters ofof thethe phylumphylum byby whichwhich theythey differdifferfromfrom allall invertebratesinvertebrates.. Later,Later, thethe characteristicscharacteristics ofof eacheach classclass includeinclude inin thethe

phylumphylum willwill bebe discusseddiscussed::

11-- TheThe presencepresence ofof aa notochordnotochord:: AllAll chordateschordates possesspossess aa longlong flexible,flexible, rodrod--

likelike supportingsupporting structurestructure knownknown asas thethe notochordnotochord.. TheThe notochordnotochord isis notnot foundfoundinin anyany groupgroup ofof invertebratesinvertebrates.. TheThe notochordnotochord eithereither persistspersists throughoutthroughout thethe

wholewhole life,life, oror maymay onlyonly appearappear inin thethe embryonicembryonic stagesstages andand thenthen becomesbecomes

graduallygradually replacedreplaced byby thethe vertebralvertebral columncolumn.. TheThe laterlater casecase isis foundfound inin higherhigher

chordates,chordates, namelynamely thethe vertebratesvertebrates..

22--AA dorsaldorsal nervenerve chordchord:: InIn chordates,chordates, therethere isis aa tubulartubular nervenerve cordcord whichwhich runerune

dorsaldorsal toto thethe notochordnotochord.. ThisThis isis contrarycontrary toto thethe casecase inin thethe invertebratesinvertebrates inin

whichwhich thethe nervenerve cordcord extendsextends alongalong thethe ventralventral sideside ofof thethe bodybody.. TheThe internalinternal

cavitycavity ofof thethe nervenerve cordcord isis knownknown asas thethe centralcentral canalcanal.. TheThe anterioranterior partpart ofof thethe

nervenerve cordcord becomesbecomes enlargedenlarged toto formform thethe brainbrain..

8/3/2019 Chordata

3/28

33-- PharyngealPharyngeal pouchespouches andand gillgill slitsslits:: chordateschordates possesspossess aa numbernumber ofof pairedpaired gillgill

pouchespouches inin thethe pharyngealpharyngeal regionregion.. TheThe pouchespouches openopen externallyexternally byby narrownarrow

openingopening knownknown asas thethe gillgill slitsslits.. SuchSuch slitsslits eithereither remainremain throughoutthroughout thethe wholewholelifelife ofof thethe animals,animals, inin whichwhich casecase theythey areare usedused forfor respirationrespiration asas inin fishes,fishes, oror

maymay onlyonly appearappear inin thethe earlyearly embryonicembryonic stages,stages, thenthen becomebecome closedclosed

graduallygradually duringduring subsequentsubsequent embryonicembryonic development,development, andand lungslungs developdevelop

insteadinstead forfor respirationrespiration..

44-- DirectionDirection ofof bloodblood flowflow inin thethe dorsaldorsal andand ventralventral bloodblood vesselsvessels:: TheThe bloodblood

flowsflows backwardsbackwards inin thethe dorsaldorsal bloodblood vesselvessel andand forwardsforwards inin thethe ventralventral bloodblood

vesselvessel.. ThisThis isis contrarycontrary toto whatwhat occursoccurs inin thethe invertebratesinvertebrates..

55--TailTail regionregion:: TheThe tailtail regionregion isis thethe partpart ofof thethe bodybody layinglaying posteriorposterior toto thethe analanalopening,opening, andand containscontains thethe endend portionportion ofof thethe notochordnotochord asas wellwell asas thethe

posteriorposterior partpart of of thethe dorsaldorsal bloodblood vesselvessel.. NoNo suchsuch postpost analanal structurestructure isis

foundfound inin vertebratesvertebrates.. TheThe tailtail eithereither remainsremains throughoutthroughout life,life, oror maymay developdevelop

onlyonly inin thethe embryonicembryonic stagesstages..

8/3/2019 Chordata

4/28

Classification of Chordata:Classification of Chordata:

Phylum Chordata is classified into three subphyla andPhylum Chordata is classified into three subphyla andmany classes as the following:many classes as the following:

11-- Subphylum Urochordata:Subphylum Urochordata:

Mostly sessile, nonmetameric invertebrate chordatesMostly sessile, nonmetameric invertebrate chordates

enclosed within a tunic containing cellulose. Pharynx highlyenclosed within a tunic containing cellulose. Pharynx highly

developed and used in filter feeding; notochord and nervedeveloped and used in filter feeding; notochord and nerve

cord present only in the larva.cord present only in the larva.

8/3/2019 Chordata

5/28

22-- Subphylum Cephalochordata:Subphylum Cephalochordata:

SmallSmall fishlikefishlike invertebrateinvertebrate chordateschordates.. MetamericMetameric butbut

trunktrunk supportedsupported byby wellwell--developeddeveloped notochordnotochord;; nono

vertebraevertebrae presentpresent--JawlessJawless suspensionsuspension feedersfeeders;; mouthmouth

surroundedsurrounded byby anan oraloral hoodhood ExpExp..,, AmphioxusAmphioxus..

33-- Subphylum VertebrataSubphylum Vertebrata::

VertebratesVertebrates.. MetamericMetameric chordateschordates withwith thethe trunktrunk

supportedsupported byby aa linearlinear seriesseries ofof cartilaginouscartilaginous oror bonybony

skeletalskeletal piecespieces (vertebrae)(vertebrae) surroundingsurrounding oror replacingreplacing

notochordnotochord inin adultadult.. MostMost vertebratesvertebrates havehave mouthmouth

surroundedsurrounded byby jawsjaws..

8/3/2019 Chordata

6/28

Characteristics ofCharacteristics of

Subphylum Vertebrata:Subphylum Vertebrata:11-- Vertebrates have a segmented backbone or vertebral column, from whichVertebrates have a segmented backbone or vertebral column, from which

the name of the subphylum is derived. They possess an axial notochordthe name of the subphylum is derived. They possess an axial notochord

during the early stages of their life but, as development proceeds, theduring the early stages of their life but, as development proceeds, the

notochord becomes invested by cartilage or bone which is divided intonotochord becomes invested by cartilage or bone which is divided into

segmental units, the vertebrae.segmental units, the vertebrae.

22-- Cranium: The vertebrata are also known as the Craniata, owing to theCranium: The vertebrata are also known as the Craniata, owing to the

presence of a cranium, or brain case, which encloses the brain.presence of a cranium, or brain case, which encloses the brain.

33-- Body regions: The body is bilaterally symmetrical. It comprises a head,Body regions: The body is bilaterally symmetrical. It comprises a head,

neck and trunk, in addition to a tail in some species.neck and trunk, in addition to a tail in some species.

8/3/2019 Chordata

7/28

44-- Appendages:There are generally two pairs of appendages which support Appendages:There are generally two pairs of appendages which support

the body and serve a locomotory function. These include two thoracicthe body and serve a locomotory function. These include two thoracic

appendages, represented pectoral fins in fishes, the wings in birds, or theappendages, represented pectoral fins in fishes, the wings in birds, or the

forefore--limbs in mammals; and two pelvic appendages, represented by the pelviclimbs in mammals; and two pelvic appendages, represented by the pelvic

fins in fishes and the hindfins in fishes and the hind--limbs in amphibians, reptiles, birds and mammals.limbs in amphibians, reptiles, birds and mammals.

55-- Integument: The skin or integument is formed of an outer epidermis ofIntegument: The skin or integument is formed of an outer epidermis of

stratified epithelium and an inner dermis of connective tissue. The skin maystratified epithelium and an inner dermis of connective tissue. The skin may

contain glands as in amphibians; or develop scales as in fishes and reptiles;contain glands as in amphibians; or develop scales as in fishes and reptiles;

feathers as in amphibians; or haris as in mammals.feathers as in amphibians; or haris as in mammals.

66--Coelom: Vertebrates have a coelomic cavity distinguished into a pericardialCoelom: Vertebrates have a coelomic cavity distinguished into a pericardial

cavity enclosing the heart, and a perivisceral cavity containing the visceralcavity enclosing the heart, and a perivisceral cavity containing the visceral

organs. In mammals, The pertivisceral cavity is further differentiated into aorgans. In mammals, The pertivisceral cavity is further differentiated into a

pleural cavity enclosing the lungs, and an abdominal cavity containing mainlypleural cavity enclosing the lungs, and an abdominal cavity containing mainly

the digestives organs.the digestives organs.

8/3/2019 Chordata

8/28

77-- Digestive system: The alimentary canal is a more or less convoluted tubeDigestive system: The alimentary canal is a more or less convoluted tube

which lies leads to the vertebral column. It begins with mouth openingwhich lies leads to the vertebral column. It begins with mouth opening

which leads to the buccal cavity. In the more primitive vertebrates, thewhich leads to the buccal cavity. In the more primitive vertebrates, the

digestive 'tract together with the urinary and genital ducts end in a commondigestive 'tract together with the urinary and genital ducts end in a common

structure, the cloaca, with opens to the exterior by the cloacal aperture. Butstructure, the cloaca, with opens to the exterior by the cloacal aperture. But

in higher vertebrates, the digestive tract has a separate opening, the anus.in higher vertebrates, the digestive tract has a separate opening, the anus.

Two digestive glands, the liver and pancreas, are found in vertebrates.Two digestive glands, the liver and pancreas, are found in vertebrates.

They convey their secretions through certain ducts into the alimentaryThey convey their secretions through certain ducts into the alimentary

canal.canal.

88-- Respiratory system: Respiration takes place in aquatic vertebrates by gills,Respiratory system: Respiration takes place in aquatic vertebrates by gills,

whereas lungs are used for this purpose in terrestrial forms. In earlywhereas lungs are used for this purpose in terrestrial forms. In early

embryonic life the lungs develop as outgrowths from the alimentary canal.embryonic life the lungs develop as outgrowths from the alimentary canal.

8/3/2019 Chordata

9/28

99-- Circulatory system: Vertebrates have a closed circulatory system in whichCirculatory system: Vertebrates have a closed circulatory system in which

blood flows into a closed system of arteries and veins. This systemblood flows into a closed system of arteries and veins. This system

includes a well developed muscular heart laying ventral to the anteriorincludes a well developed muscular heart laying ventral to the anteriorpart of the alimentary canal. The heart is formed ofpart of the alimentary canal. The heart is formed of 22--44 chambers. Thechambers. The

blood contains both white and red blood corpuscles. The latter containblood contains both white and red blood corpuscles. The latter contain

hemoglobin, which serves as a respiratory pigment.hemoglobin, which serves as a respiratory pigment.

1010-- Excretory system: This consists of two kidneys, which act to drain theExcretory system: This consists of two kidneys, which act to drain thewaste materials from the blood and eliminate them outside the body in thewaste materials from the blood and eliminate them outside the body in the

form of urine. In most vertebrates the urine is carried via certain ducts intoform of urine. In most vertebrates the urine is carried via certain ducts into

a urinary bladder which serves to store urine until it is extrudeda urinary bladder which serves to store urine until it is extruded

periodically outside the body.periodically outside the body.

1111-- Reproductive system: Usually sexes are separate in the vertebrates. TheReproductive system: Usually sexes are separate in the vertebrates. The

animal has a pair of gonads (either testes or ovaries) in which the sexualanimal has a pair of gonads (either testes or ovaries) in which the sexual

cells (sperms or ova) are produced.cells (sperms or ova) are produced.

8/3/2019 Chordata

10/28

1212-- Nervous system: In the vertebrates, there is a central nervous systemNervous system: In the vertebrates, there is a central nervous system

which is formed of brain and the spinal cord. The brain is usuallywhich is formed of brain and the spinal cord. The brain is usually

differentiated into certain regions which have different functionaldifferentiated into certain regions which have different functional

activities. Besides, there is a peripheral nervous system formed of ten toactivities. Besides, there is a peripheral nervous system formed of ten to

twelve pairs of cranial nerves arise from the brain and a number of pairedtwelve pairs of cranial nerves arise from the brain and a number of paired

spinal nerves arising from the spinal cord. Moreover, there is aspinal nerves arising from the spinal cord. Moreover, there is a

sympathetic or autonomic nervous system which regulates thesympathetic or autonomic nervous system which regulates theinvoluntary activities of the vertebrate animal. Well developed sensoryinvoluntary activities of the vertebrate animal. Well developed sensory

organs are found in the vertebrates, including those for small, sight,organs are found in the vertebrates, including those for small, sight,

hearing etc.hearing etc.

1313-- Endocrine organs: Vertebrate animals have an endocrine system formedEndocrine organs: Vertebrate animals have an endocrine system formedof a number of ductless glands, such as the thyroid, pituitary, adrenal,of a number of ductless glands, such as the thyroid, pituitary, adrenal,

etc. These glands produce certain secretions, known as control variousetc. These glands produce certain secretions, known as control various

metabolic activities of the body.metabolic activities of the body.

8/3/2019 Chordata

11/28

Economic Importance ofEconomic Importance of

Subphylum Vertebrata:Subphylum Vertebrata:Subphylum vertebrata includes class that affect directly or indirectlySubphylum vertebrata includes class that affect directly or indirectly

the agricultural production. Protein supplies for man come essentiallythe agricultural production. Protein supplies for man come essentially

from members of vertebrata. Many important products are derived fromfrom members of vertebrata. Many important products are derived from

animals related to the subphylum. Moreover, man has "used theanimals related to the subphylum. Moreover, man has "used the

domestic animals of vertebrata to fulfill his hard work.domestic animals of vertebrata to fulfill his hard work.

On the other hand, some vertebrates may cause injurious effect onOn the other hand, some vertebrates may cause injurious effect on

man and his plantations, livestock; and food stuff. Therefore, classesman and his plantations, livestock; and food stuff. Therefore, classes

that include members affecting agricultural production will bethat include members affecting agricultural production will be

discussed.discussed.

8/3/2019 Chordata

12/28

Class OsteichthyesClass Osteichthyes--11

Chanos chanosbony fishes;-Class Osteichthyes

(milk fish/bangus)

8/3/2019 Chordata

13/28

General Characters:General Characters:

11-- TheThe classclass includesincludes thethe bonybony endoskeletonendoskeleton fishes,fishes, whichwhich areare ectothermicectothermic

vertebratesvertebrates..

22-- TheirTheir integumentintegument containscontains manymany simplesimple mucousmucous glandsglands and,and, usually,usually,

bonybony scalesscales..

33-- TheirTheir skeletonskeleton isis lessless massivemassive thanthan thatthat inin terrestrialterrestrial vertebratesvertebrates.. ThereThere

isis littlelittle regionalregional differentiationdifferentiation ofof thethe vertebralvertebral columncolumn otherother thanthan trunktrunk

andand tail,tail, thethe visceralvisceral skeletonskeleton isis wellwell developeddeveloped andand thethe appendicularappendicular

skeletonskeleton consistsconsists onlyonly ofof finfin supportssupports..

8/3/2019 Chordata

14/28

44-- The eyes lacks movable eylids and tear glands. Fishes have an innerThe eyes lacks movable eylids and tear glands. Fishes have an inner

ear but no cochlea; middle and external ears are absent. Most groupsear but no cochlea; middle and external ears are absent. Most groupslack an internal nostril. The lateral line system is well developed.lack an internal nostril. The lateral line system is well developed.

55-- Their cerebrum is small and primarily an olfactory center; the optic lobesTheir cerebrum is small and primarily an olfactory center; the optic lobes

are the primary integrating center.are the primary integrating center.

66-- Fishes do not have a fleshy muscular tongue, and the intestine is notFishes do not have a fleshy muscular tongue, and the intestine is not

divided into small and large segments. A cloaca is present.divided into small and large segments. A cloaca is present.

77--Adults exchange gases with the environment through gills located in gillAdults exchange gases with the environment through gills located in gill

poaches; lungs or other access or respiratory organs are present in apoaches; lungs or other access or respiratory organs are present in a

few groups.few groups.

8/3/2019 Chordata

15/28

88-- The heart of most fishes receives only venous blood, and the atriumsThe heart of most fishes receives only venous blood, and the atriums

an ventricle are not divided. Pressures in peripheral vessels are low.an ventricle are not divided. Pressures in peripheral vessels are low.

99-- Nitrogenous wastes, primarily ammonia and urea, are eliminatedNitrogenous wastes, primarily ammonia and urea, are eliminated

through the gills in most groups and also by kidney.through the gills in most groups and also by kidney.

1010--Most males lack a copulatory organ, and fertilization is external.Most males lack a copulatory organ, and fertilization is external.

1111-- Great numbers of yolkGreat numbers of yolk--laden eggs are produced by large ovaries inladen eggs are produced by large ovaries in

most fishes.most fishes.

1212-- Most species are oviparous and pass through an aquatic larval stageMost species are oviparous and pass through an aquatic larval stage

during development.during development.

8/3/2019 Chordata

16/28

..General view of a bony fishGeneral view of a bony fishDorsal

Fin

Eye

Mouth

Heartliver

Anus

Anal fin

Dorsalfin

8/3/2019 Chordata

17/28

Economic ImportanceEconomic Importance

of fishes:of fishes:FishesFishes areare oneone ofof thethe importantimportant proteinprotein resourcesresources forfor manman demandsdemands..

PisciculturesPiscicultures areare concernedconcerned withwith rearingrearing andand raisingraising goodgood qualityquality speciesspecies

inin limitedlimited waterwater basinsbasins forfor humanhuman consumptionconsumption.. Also,Also, freshfresh waterwater fishesfishescancan successfullysuccessfully bebe raisedraised inin waterwater canalscanals andand ricerice fieldsfields.. InIn Egypt,Egypt, ricerice

growersgrowers raiseraise thethe catfish,catfish, ClariasClarias spsp.. inin theirtheir fieldsfields utilizingutilizing itit asas aa cheapcheap

sourcesource ofof foodfood;; additionaladditional sourcesource ofof financialfinancial incomeincome..

TheThe mostmost importantimportant fishfish speciesspecies commonlycommonly consumedconsumed inin EgyptEgypt whichwhichlivelive ratherrather inin naturalnatural habitatshabitats oror inin artificialartificial pisciculturespiscicultures areare;; Bulti,Bulti, TilapiaTilapia

spsp.. whichwhich liveslives inin freshfresh andand saltsalt waterwater;; mullet,mullet, MugilidusMugilidus cephaluscephalus;; catfish,catfish,

ClariasClarias sp,sp, bayad,bayad, BagrusBagrus bayadbayad;; andand eelfish,eelfish, AnguillaAnguilla vulgarisvulgaris..

8/3/2019 Chordata

18/28

Class AvesClass Aves--44Members of class Aves (Birds) are very active flying vertebrates. Most ofMembers of class Aves (Birds) are very active flying vertebrates. Most of

their distinctive characteristics are adaptations for flight, which in turntheir distinctive characteristics are adaptations for flight, which in turn

requires the maintenance of a very high level of metabolism in a body ofrequires the maintenance of a very high level of metabolism in a body of

minimum weight. Birds are found in different habitats, i.e. valleys,minimum weight. Birds are found in different habitats, i.e. valleys,

mountains, deserts, forests and over rivers and oceans. Its existencemountains, deserts, forests and over rivers and oceans. Its existence

becomes fewer in polar zones, while it increase in temperate andbecomes fewer in polar zones, while it increase in temperate and

subtropical zones. Some of which have the capability to live in dark caf,subtropical zones. Some of which have the capability to live in dark caf,

and others have the ability to dive beneath water for catching their preys.and others have the ability to dive beneath water for catching their preys.

The birds vary in size and weight; for instance, the weight of ostrich isThe birds vary in size and weight; for instance, the weight of ostrich is

aboutabout 136136 kg., while the humming bird weightskg., while the humming bird weights 11..88 grams.grams.

8/3/2019 Chordata

19/28

E

conomic Importance of birds:E

conomic Importance of birds:11-- The domestic birds are one of the most important source of proteinsThe domestic birds are one of the most important source of proteins

from animal origin.from animal origin.

22-- Feeding habits of birds determine the economic importance of eachFeeding habits of birds determine the economic importance of each

group as follows.group as follows.

aa-- Insectivorous birds: are insect eating birds, which eliminate harmfulInsectivorous birds: are insect eating birds, which eliminate harmfulinsects.insects.

bb--

Carnivorous birds: are freshCarnivorous birds: are fresh--eating birds, which may prey domesticeating birds, which may prey domestic

birds and small mammals. Hence, they are act as injurious pests.birds and small mammals. Hence, they are act as injurious pests.

8/3/2019 Chordata

20/28

cc-- Graminovorous birds: are seed and fruit eating birds, which feedGraminovorous birds: are seed and fruit eating birds, which feed

on seeds and fruits either in open fields or in granary. These group ofon seeds and fruits either in open fields or in granary. These group ofbirds cause remarkable loss in the field yields.birds cause remarkable loss in the field yields.

dd-- Herbivorous birds: are plantHerbivorous birds: are plant--eating birds, which feed on greeneating birds, which feed on green

herbs or seedlings grown in field causing effective damage on theherbs or seedlings grown in field causing effective damage on theplantations, and in turn remarkable loss in the yield.plantations, and in turn remarkable loss in the yield.

ee-- Omnivorous birds: are able to feed on various sorts of foods,Omnivorous birds: are able to feed on various sorts of foods,

which may cause a great loss to farmers.which may cause a great loss to farmers.

8/3/2019 Chordata

21/28

Class MammaliaClass Mammalia--55

Mammalia is the highest group in the Animal kingdom. It includesMammalia is the highest group in the Animal kingdom. It includesaboutabout 1515,,000000 species. The name of this class is derived from the factspecies. The name of this class is derived from the fact

that animals belonging to it feed their young by milk produced bythat animals belonging to it feed their young by milk produced by

mammary glands.mammary glands.

8/3/2019 Chordata

22/28

MammaliaMammalia

8/3/2019 Chordata

23/28

G

eneral Characters:G

eneral Characters:11-- Mammals are endothermic vertebrates.Mammals are endothermic vertebrates.22-- Hair form an insulating layer in most groups: Cutaneous glands areHair form an insulating layer in most groups: Cutaneous glands are

abundant.abundant.

33-- The body is distinguished into: a head, neck, thorax, and trunk. A tailThe body is distinguished into: a head, neck, thorax, and trunk. A tail

may be present in some forms.may be present in some forms.

44-- They possess four limbs which are situated, in most mammals, more orThey possess four limbs which are situated, in most mammals, more or

less under the body; the foot has usuallyless under the body; the foot has usually 55 toes modified for walking,toes modified for walking,

running, climbing, burrowing, swimming or flying. They have hornyrunning, climbing, burrowing, swimming or flying. They have horny

claws, toes, nails or hoofs.claws, toes, nails or hoofs.

8/3/2019 Chordata

24/28

55-- The jaws are provided with similar or dissimilar teeth which are arrangedThe jaws are provided with similar or dissimilar teeth which are arranged

into a definite manner that are represented by a dental formula.into a definite manner that are represented by a dental formula.

66-- A muscular diaphragm separates the thoracic cavity from the abdominalA muscular diaphragm separates the thoracic cavity from the abdominal

cavity.cavity.

77-- The heart isThe heart is 44 chambered, and only the left aortic arch is present. Redchambered, and only the left aortic arch is present. Red

blood cells are nonblood cells are non--nucleated.nucleated.

88-- The skull is of the synapsid type and has a relatively large brain case.The skull is of the synapsid type and has a relatively large brain case.

99-- The small intestine has numerous multiThe small intestine has numerous multi--cellular intestinal glands andcellular intestinal glands and

microscopic villi. Most species have no cloaca.microscopic villi. Most species have no cloaca.

1010-- Brain highly developed,Brain highly developed, 1212 pairs of cranial nerves.pairs of cranial nerves.

8/3/2019 Chordata

25/28

1111-- Respiratory and digestive passages are nearly completely separated inRespiratory and digestive passages are nearly completely separated in

the oral and pharyngeal regions. Numerous lung alveoli greatlythe oral and pharyngeal regions. Numerous lung alveoli greatly

increase surface area.increase surface area.

1212-- Nitrogenous wastes are eliminated, primarily as urea by metanepricNitrogenous wastes are eliminated, primarily as urea by metanepric

kidney with ureters that open usually into a bladder.kidney with ureters that open usually into a bladder.

1313-- TheThe testes of most mammals either lie permanently within a scrotum ortestes of most mammals either lie permanently within a scrotum or

descend into the scrotum during the reproductive season. Malesdescend into the scrotum during the reproductive season. Males

have a copulatory organ, and fertilization is internal.have a copulatory organ, and fertilization is internal.

8/3/2019 Chordata

26/28

1414-- ExceptExcept forfor primitiveprimitive eggegg--layinglaying mammals,mammals, thethe ovariesovaries areare smallsmall andand

produceproduce fewerfewer eggseggs thanthan inin lower lower vertebratesvertebrates;; andand littlelittle yolkyolk isis

depositeddeposited inin thethe eggseggs.. TheThe oviductsoviducts havehave differentiateddifferentiated intointo vaginal,vaginal,

uterineuterine andand uterineuterine tubetube regionsregions..

1515-- Primitive mammals (monotermes) are oviparous; other mammals arePrimitive mammals (monotermes) are oviparous; other mammals are

viviparous. Mammary glands are always present in females.viviparous. Mammary glands are always present in females.

8/3/2019 Chordata

27/28

Economic ImportanceEconomic Importance

of Mammals:of Mammals:11-- Most domestic animals are related to mammals. They are the importantMost domestic animals are related to mammals. They are the important

source of protein for human beings.source of protein for human beings.

22-- Transportation and some hard works have been accomplished byTransportation and some hard works have been accomplished by

using some mammalian animals.using some mammalian animals.

33-- Many industrial products have been manufactured depending onMany industrial products have been manufactured depending on

mammalian source.mammalian source.

44-- Insectivorous mammals feeding on insects reduce and eliminate injuryInsectivorous mammals feeding on insects reduce and eliminate injury

of such insects to man and plants.of such insects to man and plants.

8/3/2019 Chordata

28/28

55-- Carnivorous mammals may attack and prey other animals. These fleshCarnivorous mammals may attack and prey other animals. These flesh--

considerable loss in their livestocks.considerable loss in their livestocks.

66-- Rodents and their allies cause serious loss in agricultural production.Rodents and their allies cause serious loss in agricultural production.

Most of which considered as herbivorous feed on plants, fruits, seedsMost of which considered as herbivorous feed on plants, fruits, seeds

and grains. Moreover, they may attack houses of domestic birds forand grains. Moreover, they may attack houses of domestic birds for

eggs and litters stealing.eggs and litters stealing.

//..2010/20112010/2011