Frog

morphology of animals

1. Hi there!!
myself Ranatigrina

3. Kingdom Animalia
Phylum Chordata
Sub PhylumVertebrata
Section Gnathostomata
SuperclassTetrapoda
Class Amphibia
Order Anura
Family Ranidae
Genus Rana
Species tigrina
FROG : Classification

4. FROG : Features
1.Frogscanlivebothonlandandinfreshwaterandbelongto
classAmphibiaofphylumChordata.Themostcommonspecies
offrogfoundinIndiaisRanatigrina.
2.Theydonothaveconstantbodytemperaturei.e.,theirbody
temperaturevarieswiththetemperatureoftheenvironment.
Suchanimalsarecalledcoldbloodedorpoikilotherms.
3.Youmighthavealsonoticedchangesinthecolourofthefrogs
whiletheyareingrassesandondryland.Theyhavetheability
tochangethecolourtohidethemfromtheirenemies
(camouflage).Thisprotectivecolorationiscalledmimicry.
4.Youmayalsoknowthatthefrogsarenotseenduringpeak
summerandwinter.Duringthisperiodtheytakeshelterindeep
burrowstoprotectthemfromextremeheatandcold.Thisis
calledassummersleep(aestivation)andwintersleep
(hibernation).

5. FROG : Morphology
1.Theskinissmoothandslipperyduetothepresenceofmucus.
Theskinisalwaysmaintainedinamoistcondition.
2.Thecolourofdorsalsideofbodyisgenerallyolivegreenwith
darkirregularspots.Ontheventralsidetheskinisuniformlypale
yellow.
3.Thefrogneverdrinkswaterbutabsorbitthroughtheskin.
4.Bodyofafrogisdivisibleintoheadandtrunk.Aneckandtailare
absentinamaturefrog.
5.Abovethemouth,apairofnostrilsispresent.
6.Eyesarebulgedandcoveredbyanictitatingmembranethat
protectsthemwhileinwater.
7.Oneithersideofeyesamembranoustympanum(ear)receives
soundsignals.Theforelimbsandhindlimbshelpinswimming,
walking,leapingandburrowing.Thehindlimbsendinfivedigits
andtheyarelargerandmuscularthanforelimbsthatendinfour
digits.Feethavewebbeddigitsthathelpinswimming
8.Frogsexhibitsexualdimorphism.Malefrogscanbedistinguished
bythepresenceofsoundproducingvocalsacsandalsoa
copulatorypad(nuptialpad)onthefirstdigitoftheforelimbs
forclaspingthefemale

6. FROG : Digestive System
Thedigestivesystemconsistsofalimentarycanalanddigestiveglands.The
alimentarycanalisshortbecausefrogsarecarnivoresandhencethelengthof
intestineisreducedbutcompletei.efrommouthtocloaca
ALIMENTARYCANAL
1.Mouth:Themouthopensintothebuccalcavitythatleadstotheoesophagus
throughpharynx.
2.Oesophagus:Oesophagusisashort(duetoabsenceofneck)tubethatopens
intothestomach.
3.Stomach:
a)Liesontheleftsideofthebodycavity,madeupofananterior
cardiacstomachandaposteriorPyloricstomach
b)Multicellulargastricgland:pepsinogen
Unicellularoxynticgland:HCl
4.Intestine:Longestpartofthealimentarycanalanddividedintothe
duodenum,ileumandrectum(alsoknownaslargeintestine)
DIGESTIVEGLANDS
1.Liversecretesbilethatisstoredinthegallbladder
2.Pancreas,adigestiveglandproducespancreaticjuicecontainingdigestiveenzymes.

7. FROG : Digestive System
1.The frog feeds on insects, worms, molluscs etc.
2.Food is captured by the bilobedtongue and swallowed whole.
3.Digestion of food takes place by the action of HCland gastric juices
secreted from the walls of the stomach.
4.Partially digested food called chymeis passed from stomach to the first
part of the intestine, the duodenum.
5.The duodenum receives bile from gall bladder and pancreatic juices from
the pancreas through a common bile duct.
6.Bile emulsifies fat and pancreatic juices digest carbohydrates and
proteins.
7.Final digestion takes place in the intestine. Digested food is absorbed by
the numerous finger-like folds in the inner wall of intestine called villi and
microvilli.
8.The undigested solid waste moves into the rectum and passes out
through cloaca.

8. FROG : Respiratory System
1.Frogs respire on land and in the water by two
different methods.
2.a)Inwater,skinactsasaquaticrespiratoryorgan
(cutaneousrespiration).Dissolvedoxygeninthe
waterisexchangedthroughtheskinbydiffusion.
b)Onland,thebuccalcavity,skinandlungsactas
therespiratoryorgans.Therespirationby
lungsiscalledpulmonaryrespiration.
3)Thelungsareapairofelongated,pinkcoloured
sac-likestructurespresentintheupperpartofthe
trunkregion(thorax).
Airentersthroughthenostrilsintothebuccalcavity
andthentolungs.Duringaestivationandhibernation
gaseousexchangetakesplacethroughskin.

9. FROG : Blood Vascular System

10. FROG : Blood Vascular System
1.Thevascularsystemoffrogiswell-developedclosedtype,involvesheart,bloodvessels
andblood
2.Frogshavealymphaticsystemalsowhichismadupoflymph,lymphchannelsand
lymphnodes
3.Heartisamuscularstructuresituatedintheupperpartofthebodycavity.Ithasthree
chambers,twoatriaandoneventricleandiscoveredbyamembranecalledpericardium.
4.Atriangularstructurecalledsinusvenosusjoinstherightatrium.Itreceivesblood
throughthemajorveinscalledvenacava.
5.Theventricleopensintoasaclikeconusarteriosusontheventralsideoftheheart.
6.Thebloodfromtheheartiscarriedtoallpartsofthebodybythearteries(arterial
system).Theveinscollectbloodfromdifferentpartsofbodytotheheartandformthe
venoussystem.
7.Specialvenousconnectionbetweenliverandintestineaswellasthekidneyandlower
partsofthebodyarepresentinfrogs.Theformeriscalledhepaticportalsystemand
thelatteriscalledrenalportalsystem.
8.Thebloodiscomposedofplasmaandcells.
9.ThebloodcellsareRBC(redbloodcells)orerythrocytes,WBC(whitebloodcells)or
leucocytesandplatelets.
10.RBC’sarenucleated,oval,biconvexandcontainredcolouredpigmentnamely
haemoglobin.
11.Thelymphisdifferentfromblood.ItlacksfewproteinsandRBCs.
12.Thebloodcarriesnutrients,gasesandwatertotherespectivesitesduringthe
circulation.Thecirculationofbloodisachievedbythepumpingactionofthemuscular
heart.

11. FROG : Excretory System
1.Theeliminationofnitrogenouswastesiscarriedoutbyawelldeveloped
excretorysystem.
2.Theexcretorysystemconsistsofapairofkidneys,ureters,cloacaand
urinarybladder.
3.Kidneysarecompact,darkredandbeanlikestructuressituatedalittle
posteriorlyinthebodycavityonbothsidesofvertebralcolumn.
4.Eachkidneyiscomposedofseveralstructuralandfunctionalunitscalled
uriniferoustubulesornephrons.
5.Twouretersemergefromthekidneysinthemalefrogs.Theuretersactas
urinogenitalductwhichopensintothecloaca.
6.Infemalestheuretersandoviductopenseperatelyinthecloaca.
7.Thethin-walledurinarybladderispresentventraltotherectumwhichalso
opensinthecloaca.
8.Thefrogexcretesureaandthusisaureotelicanimal.
9.Excretorywastesarecarriedbybloodintothekidneywhereitisseparated
andexcreted.

12. FROG : Control & Coordination
The system for control and coordination is highly evolved in the frog. It includes both neural system and endocrine glands.
A. Endocrine System :
1.The chemical coordination of various organs of the body is achieved by hormones which are secreted by the endocrine
glands.
2.The prominent endocrine glands found in frog are pituitary, thyroid, parathyroid, thymus, pineal body, pancreatic islets,
adrenals and gonads
B. Nervous System :
1.The nervous system is organised into a
central nervous system (brain and spinal cord),
peripheral nervous system (cranial and spinal nerves) and
autonomic nervous system(sympathetic and parasympathetic).

13. FROG : Control & Coordination
CentralNervousSystem
1.Brainisenclosedinabonystructurecalledbrainbox(cranium).
2.Thebrainisdividedintofore-brain,mid-brainandhind-brain.
3.Forebrainincludesolfactorylobes,pairedcerebralhemispheresand
unpaireddiencephalon.
4.TheMidbrainischaracterisedbyapairofopticlobes.
5.Hind-brainconsistsofcerebellumandmedullaoblongata.
6.Themedullaoblongatapassesoutthroughtheforamenmagnumand
continuesintospinalcord,whichisenclosedinthevertebralcolumn
PeripheralNervousSystem
1.CranialNerves:10pairsofcranialnervesoriginatingfromthebrainoffrog
2.SpinalNerves:10pairsofspinalnervesoriginatingfromthespinalcordof
frog
AutonomicNervousSystem
Itisasystemofnervefibresandgangliawhichcontrolsandcoordinatesthe
involuntaryactivitiesofthevisceralorgans.

14. FROG : Control & Coordination
SenseOrgans
Froghasdifferenttypesofsenseorgans,
namelyorgansoftouch(sensorypapillae),taste(tastebuds),smell(nasalepithelium),vision(eyes)andhearing(tympanum
withinternalears).
Eyesandinternalearsarewell-organisedstructuresandtherestarecellularaggregationsaroundnerveendings.
Eyesinafrogareapairofsphericalstructuressituatedintheorbitinskull.
Thesearesimpleeyes(possessingonlyoneunit).
Externalearisabsentinfrogsandonlytympanumcanbeseenexternally.
Theearisanorganofhearingaswellasbalancing(equilibrium).

15. FROG : Reproductive System
MALEREPRODUCTIVESYSTEM
Itconsistsof2testes(attachedtothekidneys),severalvasaeffrentiaand2
urinogenitalducts(copulatoryorgansarelacking)
1.TESTES:
-Elongated ovoid light yellowed body attached to the upper part of the kidney
by a double fold of peritoneum called mesorchium.
-Each testes is a compact mass of coiled seminiferous tubules.
2. VASA EFFERNTIA :
-10-12 fine tubules that connect the testes to the kidney.
-They enter the kidneys on their side and open into Bidder’s canal.
-Finally it communicates with the urinogenitalduct
3. URINOGENITAL DUCT :
-In the male it is both a urinary as well as a sperm duct.
-Each duct runs posteriorly and opens into the cloaca
4. CLOACA:
-The cloaca is a small, median chamber that is used to pass faecal matter, urine
and sperms to the exterior.

16. FROG : Reproductive System
FEMALEREPRODUCTIVESYSTEM
ItconsistsofapairofOvariesandOviducts
1.OVARIES:
-Paired,irregularshapedlobulatedstructures,locatednearthekidneysbutno
connectiontothekidneys.
-Eachovarycontainsinnumerabledarkroundovaindifferentstagesof
development.
-Whenripe,theovaareshedintothebodycavityfromwheretheymoveinto
theoviducts
2.OVIDUCTS:
-Pairedlongwhiteglandularcoiledtubeslyingoneithersideofthebodycavity.
-Theposteriorendsoftheductsarebroadcalledovisacswhichopendorsally
intothecloaca.
-Eggsaretemporarilystoredintheovisacs.
-Amaturefemalefrogcanlay2500to3000ovaatatime