Animal Kingdom: Class 11 Biology Chapter 4 Hinglish mein

Pehli monsoon baarish ke baad ki shaam ko ek garden mein jao aur animals ginna shuru karo. Geeli mitti se ek earthworm bahar aata hai, ek snail hibiscus ke stem par dheere-dheere upar chadhta hai, cheentiyan line mein chalti hain, ek garden lizard deewar par intezaar karti hai aur taaron par baithi mynah awaaz deti hai. Ek talaab ya pathreela kinaara aur bhi darjanon kinds jod dega. Zoologists das lakh se kaafi zyada animal species describe kar chuke hain, aur yeh list badhti ja rahi hai: Western Ghats ke jungle se aaj bhi naye frogs ke naam rakhe ja rahe hain.

Itna bada collection bina filing system ke bekaar hai. Classification har jaane-pehchaane animal ko ek address deta hai, aur biologist ko batata hai ki ek naya describe kiya gaya species kahan belong karta hai: kin relatives ke saath, aur kis wajah se.

Mushkil kaam yeh chunna hai ki sort kis cheez se karein. Size, colour, habitat aur usefulness aasaani se bhatka dete hain: whale tairti hai par fish nahi hai, aur bat udta hai par bird nahi hai. Isliye zoologists body plan ke gehre features use karte hain jo bahut bade groups mein ek jaise rehte hain. Section 4.1 in features ko ek-ek karke leta hai; Section 4.2 inki madad se animal kingdom ko phyla mein, aur vertebrates ko classes mein, arrange karta hai.

4.1 Classification ka Basis

Animals bahar se bahut alag-alag dikhte hain, lekin andar se woh sirf kuch hi designs follow karte hain. Sea anemone aur jellyfish bilkul alag dikhte hain, aur bat aur whale bhi, lekin har pair mein tissues ki same arrangement, same symmetry aur same tarah ki body cavity hoti hai. Isliye zoologists animals ko in chhupe hue designs se sort karte hain, jaise cells kaise arranged hain, body ka layout kaisa hai aur usmein kaun si cavity hai, aur is baat se ki gut, blood system aur reproductive organs jaise organ systems kaise bane hain. Zyada tar kaam chhe features karte hain:

1. cells kaise organised hain: dheele-dhaale, tissues, organs ya organ systems mein (Section 4.1.1);
2. body apne axis ke around kaise arranged hai: uski symmetry (Section 4.1.2);
3. embryo kitni germ layers banata hai (Section 4.1.3);
4. agar body cavity hai, to kis tarah ki (Section 4.1.4);
5. kya body sach mein segmented hai (Section 4.1.5);
6. kya notochord banta hai (Section 4.1.6).

4.1.1 Organisation ke Levels

Har animal multicellular hota hai, lekin uske cells chaar tarah se organised ho sakte hain, har agla tareeka pichhle se zyada complex (Fig. 4.1). Socho, jaise-jaise ek organisation badhti hai, kaam kaise baanta jaata hai. Ek chhoti start-up mein sab log jahan zaroorat ho wahan haath bataate hain; badi company mein same skill wale log teams banate hain; teams milkar departments banti hain; aur departments judkar divisions banate hain, jinmein se har ek ek poora kaam chalata hai.

• Cellular level. Sponges mein cells sirf dheele-dhaale jude hote hain. Alag-alag cells alag-alag kaam lete hain, kuch paani ko chalate hain aur kuch skeleton banate hain, to thoda division of labour hota hai, lekin milte-julte cells kabhi milkar sachche tissues nahi banate.
• Tissue level. Hydra aur corals jaise cnidarians mein ek hi kaam karne wale cells saath baithkar ek tissue banate hain, jaise gut ko line karne wali ek sheet.
• Organ level. Flatworms ek kadam aage jaate hain: tissues milkar organs banate hain, aur har organ ek kaam ke liye specialised hota hai, jaise muscular pharynx jo khaana andar kheenchta hai.
• Organ-system level. Annelids, arthropods, molluscs, echinoderms aur chordates mein (aur, jaisa Section 4.2.5 dikhata hai, roundworms mein bhi) organs milkar systems banate hain, aur har system ek physiological function sambhalta hai: digestion, circulation, excretion waghairah.

Organ systems wale animals mein bhi saare systems ek jaise nahi bane hote. Phyla ke descriptions mein do contrasts baar-baar aayenge (Fig. 4.2):

• Incomplete digestive system: gut ek band thaili hai jiska ek hi opening mouth aur anus dono ka kaam karta hai. Flatworms aise hi bane hote hain.
• Complete digestive system: gut do openings wali ek tube hai, ek mouth jahan se khaana andar aata hai aur ek anus jahan se waste bahar jaata hai, isliye khaana ek hi direction mein chalta hai aur har region specialise ho sakta hai.
• Open circulatory system: heart blood ko kisi band network ke bajaye khuli jagahon mein push karta hai, isliye cells aur tissues seedhe blood mein doobe rehte hain (arthropods, zyada tar molluscs).
• Closed circulatory system: blood poore samay tubes ke andar hi rehta hai, aur alag-alag chaudai ki arteries, capillaries aur veins se hokar chalta hai (annelids, chordates).

4.1.2 Symmetry

Socho ki ek chapti blade, yaani ek plane, se animal ki body ko beech se kaata jaaye. Agar dono tukde ek doosre ki mirror image hain, to woh plane ek plane of symmetry hai. Aise kitne planes hain, yeh ginkar animals teen groups mein baant jaate hain (Fig. 4.3).

• Asymmetrical: centre se koi bhi cut matching halves nahi deta. Zyada tar sponges aise hi badhte hain, unka shape chattaan aur current tay karte hain.
• Radial symmetry (अरीय सममिति): body ek central axis ke around bani hoti hai, jaise ek pahiya ya gol cake, isliye axis ko contain karne wala koi bhi plane identical halves deta hai. Cnidarians, ctenophores aur adult echinoderms radial hote hain.
• Bilateral symmetry: sirf ek plane, jo head se tail tak beech mein chalta hai, matching left aur right halves deta hai. Annelids, arthropods, chordates aur baaki zyada tar phyla bilateral hain.

Symmetry jeene ke tareeke ke hisaab se hoti hai. Ek radial animal, jo chattaan se chipka ho ya behta ho, khaane aur khatre se har taraf se barabar milta hai. Ek bilateral animal head pehle karke chalta hai, isliye uske sense organs aage wale end par jama ho jaate hain, yahi ek sachche head ki shuruaat hai.

4.1.3 Diploblastic aur Triploblastic Organisation

Development ki shuruaat mein embryo apne cells ko sheets mein arrange karta hai jinhe germ layers kehte hain, aur har layer aage chalkar khaas tissues banati hai. Kitni layers banti hain, yeh ek basic character hai (Fig. 4.4).

Diploblastic animals sirf do layers banate hain: bahar ki ectoderm aur andar ki endoderm. Dono ke beech mesoglea hoti hai, ek jelly jaisi layer jo kabhi organised cell layer nahi banti. Cnidarians iska standard example hain; ctenophores bhi diploblastic hain.

Triploblastic animals ek teesri layer jodte hain, mesoderm, jo ectoderm aur endoderm ke beech sandwich hoti hai. Platyhelminthes se lekar Chordata tak har phylum triploblastic hai. Mesoderm muscles banati hai aur, jaisa agla section dikhata hai, yeh tay karti hai ki animal mein kis tarah ki body cavity banegi.

4.1.4 Coelom

Kai animals mein ek fluid se bhari jagah hoti hai jo gut ko body wall se alag karti hai. Yeh jagah hai ya nahi, aur ise kaun sa tissue line karta hai, yeh poore animal classification ke sabse useful characters mein se ek hai.

Teen plans ho sakte hain (Fig. 4.5):

• Coelomates mein sachcha coelom hota hai, jismein mesoderm body-wall wali side aur gut wali side dono ko line karti hai: annelids, molluscs, arthropods, echinoderms, hemichordates aur chordates.
• Pseudocoelomates mein bhi cavity hoti hai, lekin use koi line nahi karta: unki mesoderm bahar aur andar ki layers ke beech bikhri alag-alag pockets tak simat jaati hai. Aisi cavity ek pseudocoelom, yaani false coelom, hai, aur yeh Aschelminthes (roundworms) mein milti hai.
• Acoelomates mein koi cavity hoti hi nahi; gut aur body wall ke beech ki poori jagah mesoderm se bhari hoti hai. Platyhelminthes (flatworms) acoelomate hain.

Coelom itna important kyun hai? Isse gut aur body wall alag-alag move kar sakte hain, to body rengte waqt bhi khaana mathha ja sakta hai, aur organs ko badhne aur khisakne ki jagah milti hai. Earthworms mein coelomic fluid ek liquid skeleton ka kaam bhi karta hai, jiske against muscles mitti khodte waqt push karti hain.

4.1.5 Segmentation

Earthworm par ungli phiraao to rings mehsoos hoti hain. Yeh sirf skin tak nahi hain. Patli andar ki deewarein, septa, andar ki jagah ko ek jaise compartments mein baantti hain, aur same organs, jaise nerve ganglion aur excretory nephridia, ek ke baad ek compartment mein dobara milte hain (Fig. 4.6).

Jo body ek jaise segments ki row ki tarah bani ho, bahar aur andar dono taraf divided ho, aur kuch organs har segment mein repeat hon, woh metameric segmentation dikhati hai; is phenomenon ko metamerism kehte hain. Tapeworm ki units ki lambi chain ek useful contrast hai: yeh units, proglottids, head ke peeche reproductive packets ki tarah bud hokar banti hain, isliye tapeworm sach mein metameric nahi hai. Is chapter ke phyla ke sequence mein true segmentation pehli baar Annelida mein aata hai.

4.1.6 Notochord

Notochord (पृष्ठरज्जु) ek flexible rod hai jo kuch embryos ki peeth, yaani dorsal side, ke saath banti hai. Yeh mesoderm se banti hai aur body ko tab sakht rakhti hai jab baaki embryo abhi naram hota hai.

Jo animals life ki kisi stage par notochord banate hain woh chordates hain; baaki sab non-chordates hain. Porifera se Echinodermata tak non-chordates hain, aur Hemichordata bhi, jiski notochord jaisi dikhne wali rod asal mein true notochord nahi nikalti (Section 4.2.10). Tumhare jaise vertebrates mein embryo ki notochord zyada tar backbone se replace ho jaati hai (chordate subphyla).

4.2 Animals ka Classification

Section 4.1 ke features ko saath rakho to animal kingdom ek branching scheme mein bant jaata hai. Fig. 4.7 ek key ki tarah padha jaata hai: har fork par ek question ka jawab do, aur har jawab choice ko chhota karta jaata hai jab tak ek hi phylum na bache.

Pehle kuch questions bahut kuch tay kar dete hain. Level of organisation sponges ko baaki sabse alag karta hai. Symmetry, jo germ layers ki sankhya ke saath-saath chalti hai, radial, diploblastic cnidarians aur ctenophores ko bilateral, triploblastic majority se alag karti hai. Phir body cavity flatworms, roundworms aur chhe coelomate phyla ko alag karti hai. Coelomates mein notochord Chordata ko pehchaan leti hai, aur baaki har phylum ka apna ek hallmark hai. Echinoderms tricky case hain: unke larvae bilateral hote hain par adults radial ho jaate hain, isliye key unhe coelomates ke saath rakhti hai aur unki symmetry par note lagati hai.

4.2.1 Phylum – Porifera

Pehle nahaane ke liye bikne wala naram, peela-sa natural sponge asal mein ek animal ka skeleton tha. Sponges adult hokar kabhi move nahi karte aur unmein na mouth hota hai, na gut, na nerves, phir bhi woh animals hain: unke bahut saare cells milkar paani filter karke khaana lete hain.

Sponge ko chalane wali cheez hai uske canals aur central cavity ke saath choanocytes, yaani collar cells, ki lining. Har ek mein ek hilta hua flagellum hota hai jo paani ko aage kheenchta hai aur baareek projections ka ek collar jo khaana pakadta hai. Inki mili-juli koshish se paani anginat chhote pores, ostia, se andar ek central cavity, spongocoel, mein aata hai aur upar ke ek bade opening, osculum, se bahar nikal jaata hai (Fig. 4.9). Yahi ek current khaana laata hai, gases exchange karta hai aur wastes ko le jaata hai.

• Hallmark: water canal system (ostia → spongocoel → osculum), jo choanocytes se lined hota hai.
• Body plan: cellular level, koi true tissues nahi; zyada tar asymmetrical. Sponges ko primitive multicellular animals maana jaata hai.
• Feeding: filter feeding; digestion intracellular hota hai.
• Support: spicules (chhoti mineral sui) ya spongin fibres ka skeleton.
• Reproduction: hermaphrodite, yaani ek hi sponge eggs aur sperm dono banata hai. Toote hue tukde naye sponges ban jaate hain (asexual); gametes se sexual raasta milta hai, internal fertilisation ke saath. Development indirect hota hai, ek aise larva se hokar jo adult se bilkul alag hota hai.
• Habitat: aam taur par marine; Spongilla un gine-chune sponges mein se hai jo meethe paani mein rehte hain.
• Examples: Euspongia (bath sponge), Spongilla (freshwater sponge) aur Sycon (jise Scypha bhi kehte hain).

4.2.2 Phylum – Coelenterata (Cnidaria)

Indian beaches par tairne wale kabhi-kabhi jellyfish ki wajah se laal, jalte hue nishaan lekar samudra se bahar aate hain. Yahi dank is phylum ko uska doosra naam, Cnidaria, deta hai. Yeh cnidoblasts (cnidocytes) se aata hai, aise cells jinmein se har ek mein ek capsule, nematocyst, hota hai jismein ek coiled thread bhara hota hai. Cnidoblasts tentacles aur body par jade hote hain, jahan woh animal ko chipkaane, uski raksha karne aur shikaar pakadne ka kaam karte hain (Fig. 4.10).

Cnidarians ke do basic body forms hote hain. Polyp ek cylinder hai jo apne base se chipka hota hai, mouth aur tentacles upar ki taraf, jaise Hydra ya sea anemone Adamsia. Medusa ek free-swimming, chhatri jaisi bell hai jiska mouth neeche ki taraf hota hai, jaise jellyfish Aurelia. Asal mein medusa ek ulta aur chapta kiya hua polyp hi hai.

Kuch cnidarians, jaise Obelia, dono forms se guzarte hain. Unke polyps budding se asexually medusae banate hain; medusae eggs aur sperm banate hain, aur zygote ek larva se hokar naye polyps mein badhta hai, yeh sexual raasta hai. Asexual polyp generation aur sexual medusa generation ke beech ki is alternation ko metagenesis kehte hain (Fig. 4.11).

• Body plan: tissue level, diploblastic aur radially symmetrical.
• Feeding: khaana andar aata hai aur wastes bahar jaate hain ek hi mouth se, jo ek uthe hue cone, hypostome, par hota hai; yeh central gastro-vascular cavity mein khulta hai. Digestion cavity mein shuru hota hai (extracellular) aur lining cells ke andar poora hota hai (intracellular).
• Skeleton: reef banane wale corals calcium carbonate, $\mathrm{C}\mathrm{a}\mathrm{C}\mathrm{O}{\phantom{X}}_3$, secrete karte hain, yahi Lakshadweep aur Andaman Islands ke aas-paas ki reefs ka material hai.
• Habitat: aquatic aur zyada tar marine; kuch ek jagah chipke rehte hain (sessile) jabki baaki aazaadi se tairte hain.
• Examples: tairti, colonial Physalia (Portuguese man-of-war)11Portuguese man-of-war ek animal nahi balki kai specialised individuals ki colony hai.; reef banane wale Meandrina (brain coral) aur Gorgonia (sea fan); feather jaisa Pennatula (sea pen); aur Adamsia, ek sea anemone.

4.2.3 Phylum – Ctenophora

Ctenophores, jinhe comb jellies ya sea walnuts kehte hain, kaanch jaisi chhoti jellyfish lagte hain par apna alag phylum banate hain. Inka hallmark hai body ke saath neeche chalti comb plates ki aath rows, har plate fused cilia ka ek band. Plates lehron mein hilti hain jo animal ko aage chalati hain aur dhoop mein rainbow jaise rang chamkaati hain. Kai ctenophores chamakte bhi hain: bioluminescence, yaani living body dwara banai gayi roshni, is group ka ek khaas feature hai.

• Body plan: tissue level, diploblastic aur radial, cnidarians ki tarah, lekin stinging cells nahi hote.
• Feeding: digestion kuch extracellular aur kuch intracellular hota hai.
• Reproduction: hermaphrodite; reproduction sirf sexual hota hai, external fertilisation aur indirect development ke saath.
• Habitat: sirf marine.
• Examples: Ctenoplana aur Pleurobrachia.

4.2.4 Phylum – Platyhelminthes

Flatworms upar se neeche (dorsoventrally) chapte hote hain, isi se unka common name aaya hai. Chapti body har cell ko surface ke paas rakhti hai, jo aise animal ke liye madadgaar hai jismein na circulatory organs hain na saans lene wale organs. Kai flatworms insaanon aur pashuon ke parasites hain: Taenia, yaani tapeworm, kachche pake infected pork se insaanon tak pahunchta hai, aur Fasciola, yaani liver fluke, bhed aur gaay-bhains ke liver mein rehta hai.

• Hallmark: chapti body; parasitic forms mein host ko pakadne ke liye hooks aur suckers hote hain.
• Body plan: bilateral, triploblastic aur acoelomate, organ level of organisation par.
• Feeding: kuch parasites, jaise tapeworm, host ka pacha hua khaana seedhe apni body surface se absorb kar lete hain.
• Excretion: specialised flame cells excretion aur osmoregulation sambhalte hain.
• Reproduction: hermaphrodite, internal fertilisation ke saath; development kai larval stages se hokar hota hai.
• Regeneration: free-living Planaria ek chhote tukde se poori body dobara bana sakta hai.
• Habitat: zyada tar doosre animals, insaanon samet, ke andar rehne wale endoparasites.
• Examples: Fasciola (liver fluke) aur Taenia (tapeworm).

4.2.5 Phylum – Aschelminthes

Roundworm ko aar-paar kaato to slice ek circle hota hai, isi se common name samajh aata hai. Teen human parasites standard examples hain: Ascaris, yaani bada intestinal roundworm; Wuchereria, yaani filarial worm, jiske larvae mosquitoes phailate hain aur jo filariasis karta hai; aur Ancylostoma, yaani hookworm. Inse hone wali bimaariyon ke baare mein tum Class 12 (Human Health and Disease) mein padhoge.

• Hallmark: cross-section mein gol body, pseudocoelom ke saath.
• Body plan: organ-system level; bilateral aur triploblastic.
• Feeding: complete gut, mouth se ek well-developed muscular pharynx hote hue anus tak.
• Excretion: ek excretory tube wastes ko body cavity se ek excretory pore ke zariye bahar nikalti hai.
• Reproduction: sexes alag (dioecious), female aksar male se lambi hoti hai; internal fertilisation; development direct (young chhote adults jaise) ya indirect (larvae se hokar).
• Habitat: mitti aur paani mein free-living, ya plants aur animals mein parasitic.

4.2.6 Phylum – Annelida

Yeh naam Latin shabd annulus, yaani chhoti ring, se aaya hai, un rings ke kaaran jo tumne Section 4.1.5 mein earthworm par dekhi thi. Yeh rings true metameres hain, jo bahar ke saath andar bhi repeat hoti hain.

• Hallmark: true metameric segmentation; segments, yaani metameres, surface par dikhte hain aur andar repeat hote hain.
• Body plan: organ-system level; bilateral, triploblastic aur coelomate.
• Movement: longitudinal aur circular muscles milkar locomotion karti hain; marine Nereis mein tairne ke liye paddle jaise side flaps, parapodia, bhi hote hain.
• Transport aur excretion: closed circulatory system; nephridia (singular nephridium) excretion aur osmoregulation sambhalte hain.
• Nerves: ek double ventral nerve cord jis par paired ganglia (singular ganglion) hote hain, aur lateral nerves body tak shaakhaon ki tarah jaati hain.
• Reproduction: sexual. Nereis mein sexes alag hote hain (dioecious), jabki earthworms aur leeches monoecious hote hain, har individual mein dono sexes.
• Habitat: samudra, meetha paani aur zameen; zyada tar free-living, kuch parasitic.
• Examples: Pheretima, Indian mitti ka earthworm; tairne wala marine worm Nereis; aur Hirudinaria, ek leech jo blood peeta hai.

4.2.7 Phylum – Arthropoda

Scientists ne jitni animal species ke naam rakhe hain unhe gino, to har teen mein se do se zyada arthropods nikalti hain, sabse zyada insects. Isliye Arthropoda sabse bada phylum hai, kaafi bade margin se: har named vertebrate ke mukaable insects ki das se zyada kinds ke naam rakhe gaye hain.

Do features is phylum ko uski success aur uska naam dete hain. Chitinous exoskeleton body ki raksha karta hai aur paani ka nuksaan kam karta hai, jisse arthropods ke liye sookhi zameen khul gayi. Aur body mein jointed appendages hote hain: Arthropoda naam Greek ke arthron, yaani joint, aur pous (podos), yaani foot, ko jodta hai.

• Body plan: organ-system level; bilateral, triploblastic, segmented aur coelomate; body teen regions mein hoti hai, head, thorax aur abdomen.
• Saans lena: gills (prawns), book gills (king crab), book lungs (scorpions, spiders) ya tracheal system (insects).
• Circulation: open hota hai.
• Senses: antennae; compound aur simple eyes; statocysts, jo balance ke organs hain.
• Excretion: Malpighian tubules se.
• Reproduction: zyada tar dioecious; fertilisation aam taur par internal; zyada tar oviparous (ande dene wale); development direct, ya larvae se hokar indirect jaise butterflies mein.

4.2.8 Phylum – Mollusca

Mollusca doosra sabse bada animal phylum hai. Garden snail, pearl oyster, cuttlefish aur octopus bahut alag dikhte hain, phir bhi sab ek hi plan par bane hain (Fig. 4.12).

Is plan ke har part ka ek kaam hai. Neeche ka muscular foot animal ko chalata hai, snails mein rengkar aur tusk shells mein khodkar. Upar ka visceral hump zyada tar organs ko rakhta hai. Aage ka head sensory tentacles aur mouth rakhta hai, aur mouth ke andar radula hoti hai, chhote daanton ka ek ribbon jo file ki tarah khaana ghiste hai. Hump ke upar skin ka ek naram, spongy fold, mantle, dhaka hota hai, jo aam taur par ek calcareous shell banata hai. Mantle aur hump ke beech mantle cavity hoti hai, jahan feather jaise gills saans lene aur excretion dono ka kaam karte hain.

• Body plan: organ-system level; bilateral, triploblastic, coelomate aur unsegmented.
• Shell: aam taur par bahari aur calcareous; cuttlefish aur squids mein chhota aur andar, aur Octopus mein hota hi nahi.
• Reproduction: sexes aam taur par alag; ande diye jaate hain, aur young ek larval stage se guzarte hain (indirect development).
• Habitat: zameen, meetha paani aur samudra.
• Examples: snails aur unke rishtedaar, Pila (apple snail) aur Aplysia (sea hare); do shells wala ek bivalve, Pinctada (pearl oyster); tez tairne wale cephalopods Octopus (devil fish), Sepia (cuttlefish) aur Loligo (squid); aur do ajeeb shapes, Dentalium (tusk shell) aur Chaetopleura (chiton).

Pila Indian talaabon aur dhaan ke kheton ka bada snail hai, aur ek samay pearls ne Gulf of Mannar ke kinaare ko mashhoor kiya tha. Dhyaan do ki cuttlefish aur devil fish bilkul bhi fish nahi hain: common names bhatka sakte hain, aur isi wajah se scientific names hote hain.

4.2.9 Phylum – Echinodermata

Starfish ko palto to tumhe chattaan ko pakde sainkdon chhote, naram tube feet dikhenge. Yeh uske water vascular system ke kaam karne wale sire hain, paani se bhari canals ka network jo sirf echinoderms mein hota hai. Yeh system animal ko chalata hai, khaana pakadta aur aage badhata hai, aur saans lene mein madad karta hai.

Is group ke naam ka matlab hai kaanton wali skin. Kaante aur ubhaar calcareous ossicles ke endoskeleton se aate hain, yaani calcium carbonate ki chhoti plates jo skin ke theek neeche hoti hain.

• Body plan: organ-system level; triploblastic aur coelomate. Symmetry umar ke saath badalti hai: free-swimming larva bilateral hota hai, adult radial.
• Feeding: complete gut, mouth neeche ki (ventral) surface par aur anus upar ki (dorsal) surface par.
• Excretion: koi excretory system nahi hota.
• Reproduction: sexes alag; reproduction sexual; fertilisation aam taur par external; development indirect, ek free-swimming larva se hokar.
• Habitat: har echinoderm samudra mein rehta hai.
• Examples: arms wale do, Asterias (starfish) aur Ophiura (brittle star); gend jaisa Echinus (sea urchin); sausage jaisa Cucumaria (sea cucumber); aur Antedon (sea lily), jo ek pankhon wale plant jaisa dikhta hai. Starfish fish nahi hai aur sea lily plant nahi hai.

4.2.10 Phylum – Hemichordata

Balanoglossus aur Saccoglossus jaise acorn worms Hemichordata banate hain, jo samudra ki satah par rehne wale worm jaise animals ka ek chhota phylum hai. Cylindrical body ke teen parts hote hain: aage proboscis, ek chhota collar aur ek lamba trunk.

Collar mein ek chhoti, rudimentary rod hoti hai, stomochord. Kyunki yeh notochord jaisi dikhti hai, isliye pehle hemichordates ko Chordata ka ek subphylum maana jaata tha. Dhyaan se study karne par pata chala ki yeh true notochord nahi hai, isliye Hemichordata ab non-chordates mein ek alag phylum hai.

• Body plan: organ-system level; bilateral, triploblastic aur coelomate.
• Transport, saans aur excretion: open circulatory system; saans ke liye gills; excretion ke liye proboscis gland.
• Reproduction: sexes alag, external fertilisation aur indirect development.
• Habitat: samudra ki satah mein bil banane wale worm jaise animals.

4.2.11 Phylum – Chordata

Tumhara apna phylum Chordata hai. Chaar characters, jo kam se kam embryo mein to zaroor hote hain, ise define karte hain (Fig. 4.13):

1. peeth ke saath ek notochord;
2. notochord ke upar ek dorsal, hollow nerve cord;
3. paired pharyngeal gill slits, gale (pharynx) ki wall mein openings;
4. ek post-anal tail, body ka woh part jo anus ke peeche bhi aage chalta hai.

Chordates bilateral, triploblastic, coelomate aur organ-system level par organised bhi hote hain, aur unka circulatory system closed hota hai. Insaanon mein gill region aur tail sirf early embryo mein saaf dikhte hain aur baad mein badal jaate hain, isliye chordate characters dhoondhne ke liye aksar embryo hi sahi jagah hai.

Subphyla: protochordates aur vertebrates

Notochord ka kya hota hai, isse Chordata teen subphyla mein bantata hai (Fig. 4.14):

• Urochordata (Tunicata): notochord sirf tairne wale larva ki tail mein hoti hai aur jab larva baith kar thaili jaisa adult banta hai to gayab ho jaati hai. Examples: Ascidia, Salpa aur Doliolum.
• Cephalochordata: notochord head se tail tak chalti hai aur animal ki poori life rehti hai. Example: Branchiostoma (Amphioxus, yaani lancelet).
• Vertebrata: notochord embryo mein banti hai aur adult mein cartilage ya bone ke vertebral column se replace ho jaati hai.

Urochordates aur cephalochordates milkar protochordates kehlaate hain, aur dono sirf samudra mein rehte hain. Kyunki har vertebrate ek notochord stage se guzarta hai, isliye vertebrates poori tarah Chordata ke andar aate hain; lekin Chordata mein protochordates bhi hain, jo kabhi backbone nahi banate. Chordate characters ke alawa vertebrates mein teen aur cheezein common hain: ek muscular, ventral heart, jo do, teen ya chaar chambers wala ho sakta hai; kidneys ka ek pair jo wastes nikalta hai aur paani aur salts ka balance rakhta hai; aur paired appendages, fins ya limbs.

Vertebrates ko pehle jaws se aur phir is baat se sort kiya jaata hai ki woh kis cheez se move karte hain:

• Division Agnatha (jaws nahi): class Cyclostomata.
• Division Gnathostomata (jaws), superclass Pisces (fins): classes Chondrichthyes aur Osteichthyes.
• Division Gnathostomata, superclass Tetrapoda (limbs): classes Amphibia, Reptilia, Aves aur Mammalia.

4.2.11.1 Class – Cyclostomata

Lamprey ki life samudra aur nadi ke beech jhoolti hai. Adults samudra mein rehte hain, spawn karne ke liye tairkar meethe paani mein upar jaate hain aur spawning ke kuch hi dinon mein mar jaate hain; unke larvae metamorphosis se guzarte hain aur phir wapas ocean ki taraf laut jaate hain. Lampreys aur hagfishes hi aaj ke jinda jawless vertebrates hain.

• Hallmark: jaws nahi; unki jagah ek gol sucking mouth.
• Skeleton aur body: lambi aur eel jaisi; cranium aur vertebral column cartilaginous hote hain; paired fins nahi hote.
• Skin: scales nahi.
• Saans aur circulation: gill slits ke 6 se 15 pairs; closed circulation.
• Lifestyle: saare living members ko kuch fishes par ectoparasites bataya jaata hai; lamprey chipak kar host ki skin ko ghis deta hai.22Sahi kahein to yeh lamprey ka jeene ka tareeka hai; hagfishes zyada tar mari ya marti hui fish khaati hain aur kabhi meethe paani mein nahi jaatin. Exam answers yahan di gayi class description ko follow karte hain.
• Examples: lamprey, Petromyzon, aur hagfish, Myxine.

4.2.11.2 Class – Chondrichthyes

Shark ko tail se head ki taraf sehlaao to uski skin sandpaper jaisi lagti hai. Yeh khurdurapan sakht skin mein lage bahut chhote placoid scales se aata hai, aur shark ke peeche ki taraf mude daant bhi modified placoid scales hi hain, yaani daant aur skin ek hi structure ke alag roop hain. Sharks, rays aur sawfishes cartilaginous fishes ki yeh class banate hain.

Inki ek buoyancy ki problem bhi hai. Air bladder na hone se cartilaginous fish samudra ke paani se zyada dense hoti hai aur use tairte rehna padta hai, warna woh dheere-dheere doob jaati hai.

• Skeleton aur body: cartilage ka endoskeleton; notochord poori life rehti hai. Streamlined, mouth neeche ki taraf (ventral) aur bahut taakatwar jaws: yeh predators hain.
• Gills: har gill slit alag khulti hai; koi gill cover (operculum) nahi hota.
• Heart aur temperature: do chambers wala heart, ek auricle aur ek ventricle. Saari fishes ki tarah yeh bhi poikilothermous (असमतापी), yaani cold-blooded hain: apna body temperature regulate nahi kar sakte, jo paani ke saath badalta rehta hai.
• Reproduction: sexes alag; males mein pelvic fins par claspers hote hain; fertilisation internal; kai species viviparous hain, jo jinda bachchon ko janm deti hain.
• Khaas hathiyaar: Torpedo (electric ray) mein electric organs aur Trygon (sting ray) mein poison sting.
• Habitat: marine, yaani samudra mein.
• Examples: Carcharodon (great white shark), Scoliodon (dogfish), Pristis (sawfish) aur Trygon (sting ray).

4.2.11.3 Class – Osteichthyes

Indian khaane ki plate par zyada tar fish bony fishes hoti hain: talaabon se rohu aur katla, daldal se magur, samudra se pomfret aur hilsa. Sharks ke ulat, bony fish paani mein ek jagah tiki reh sakti hai, kyunki uski body ke andar gas se bhara air bladder uski buoyancy adjust karta hai.

• Skeleton aur body: bone ka endoskeleton; streamlined body; mouth zyada tar aage ke sire par (terminal).
• Gills: chaar pairs, head ki har side par ek bony flap, operculum, se dhake hue.
• Skin: cycloid ya ctenoid scales.
• Heart aur temperature: do chambers, ek auricle aur ek ventricle; cold-blooded.
• Reproduction: sexes alag; fertilisation aam taur par external; zyada tar oviparous; development direct.
• Habitat: samudra aur meetha paani dono.
• Examples: nadiyon aur talaabon mein Labeo (rohu), Catla (katla) aur Clarias (magur); samudra mein Exocoetus, yaani flying fish, aur Hippocampus, yaani sea horse; ghar ke aquariums mein Betta (fighting fish) aur Pterophyllum (angel fish).

4.2.11.4 Class – Amphibia

Naam hi sab bata deta hai: Greek amphi, yaani dono ya dual, aur bios, yaani life. Frog talaab mein gills wale tadpole ki tarah shuru hota hai aur hawa mein saans lene wale adult ki tarah khatam hota hai jo zameen par kood-kood kar chalta hai, aur yahi dohri life poori class ko shape deti hai.

• Skin: geeli aur bina scales ki; yeh saans lene ki surface ka kaam bhi karti hai.
• Saans aur heart: gills, lungs aur skin, sab saans lene mein use hote hain; heart mein teen chambers hote hain, do auricles aur ek ventricle; cold-blooded.
• Body: head aur trunk mein divided; zyada tar mein limbs ke do pairs hote hain, aur kuch, jaise salamanders, tail bhi rakhte hain.
• Senses: aankhon par eyelids; head ki side par ek drum jaisi membrane, tympanum, ear ka kaam karti hai.
• Cloaca: gut, urinary tract aur reproductive tract, sab ek chamber, cloaca, mein khulte hain, jo bahar khulta hai.
• Reproduction: sexes alag; fertilisation external; ande diye jaate hain; development indirect, ek larva (tadpole) se hokar.
• Examples: frog Rana aur toad Bufo, ped par chadhne wala tree frog Hyla, tail wala Salamandra (salamander) aur bina legs wala Ichthyophis.

Chapter 7 mein hum frog ko detail mein dekhenge.

4.2.11.5 Class – Reptilia

Reptiles ka naam Latin repere se aaya hai, yaani rengna. Inki pehchaan hai sookhi, cornified skin jo epidermal scales ya badi horny plates, scutes, se dhaki hoti hai. Snakes aur lizards samay-samay par bahari layer ko skin cast ki tarah utaar dete hain, yahi kaagaz jaisi kenchuli kabhi-kabhi garden mein milti hai.

• Ears: koi external ear opening nahi; tympanum ear ka kaam karta hai.
• Limbs: agar hon to do pairs; snakes mein nahi hote.
• Heart aur temperature: zyada tar mein heart ke teen chambers, crocodiles mein chaar; reptiles poikilotherms hain.
• Reproduction: sexes alag; fertilisation internal; oviparous; development direct.
• Habitat: zyada tar zameen par.
• Examples: lizards jaise Calotes (garden lizard), Hemidactylus (wall lizard) aur Chameleon (tree lizard); shell wale reptiles, zameen par Testudo (tortoise) aur samudra mein Chelone (turtle); crocodilians Crocodilus aur Alligator; aur teen zehrile snakes, Naja (cobra), Bungarus (krait) aur Vipera (viper).33Kuch printings mein krait ke genus ki spelling Bangarus hai; maani hui spelling Bungarus hai.

4.2.11.6 Class – Aves

Feathers hi bird ko bird banate hain: kisi aur living animal mein yeh nahi hote. Zyada tar birds udte hain, aur bird ki body ka bahut kuch isi zaroorat se shape hua hai; ostrich un exceptions mein se ek hai jo ud nahi sakte.

• Udne ke liye bana: forelimbs wings mein badal gaye hain; poori tarah ossified skeleton jiski lambi bones pneumatic hoti hain, yaani air cavities ke saath khokhli, jisse skeleton halka rehta hai; lungs se jude air sacs saans lene mein madad karte hain.
• Beak aur gut: daanton ki jagah beak; gut mein do extra chambers, crop, jo khaana store karta hai, aur gizzard, jo use peesta hai.
• Skin: sookhi, tail ki jad ke paas ek oil gland ke alawa koi glands nahi, jo pankh saaf karne (preening) mein kaam aata hai; hind limbs par aam taur par scales hote hain aur woh chalne, tairne ya shaakhaon ko pakadne ke liye adapted hote hain.
• Heart aur temperature: poori tarah chaar chambers wala heart; birds homoiothermous (समतापी), yaani warm-blooded hote hain, mausam kaisa bhi ho, body temperature ek jaisa rakhte hain.
• Reproduction: sexes alag; fertilisation internal; oviparous; development direct.
• Examples: na udne wale Struthio (ostrich) aur Aptenodytes (penguin), aur Pavo (peacock), Psittacula (parrot), Neophron (vulture), Columba (pigeon) aur Corvus (crow).

4.2.11.7 Class – Mammalia

Mammals Ladakh ke barfeele maidaanon se Thar desert tak, rainforests se sabse andheri caves tak milte hain. Bats hawa mein pahunch gaye hain, aur dolphins aur whales apni poori life paani mein bitaate hain.

Inka sabse khaas feature hai mammary glands, jo bachchon ke poshan ke liye doodh banati hain; mammal shabd inhi se aaya hai.

• Skin aur ears: skin par hair; bahari ear flaps, pinnae.
• Teeth: jaws mein alag-alag tarah ke daant.
• Limbs: do pairs, har tarah ki movement ke hisaab se bane: horse mein daudne ke liye hooves, monkey mein pakadne wale haath, pangolin mein khodne wale claws, dolphin mein flippers aur bat mein wings.
• Heart, lungs aur temperature: chaar chambers wala heart; lungs se saans; homoiothermous.
• Reproduction: sexes alag; fertilisation internal; kuch exceptions ko chhodkar viviparous (platypus, Ornithorhynchus, ande deta hai); development direct.
• Examples: ande dene wala Ornithorhynchus (platypus); hawa mein Pteropus (flying fox); samudra mein Delphinus (common dolphin) aur Balaenoptera (blue whale, sabse bada jaana-pehchaana animal); pouch wala Macropus (kangaroo); aur zameen par Elephas (elephant), Panthera tigris (tiger), Panthera leo (lion), Camelus (camel), Equus (horse), Macaca (monkey), Canis (dog), Felis (cat) aur Rattus (rat).

Vertebrate classes ki tulna

Classes mein do trends chalte hain. Heart mein chambers badhte jaate hain (Fig. 4.15), aur body dheere-dheere paani aur bahar ke temperature par kam nirbhar hoti jaati hai. Neeche ki table jaws wali classes ko feature by feature saath rakhti hai.

Ek nazar mein phyla

Table 4.2 revision ke liye saare gyarah phyla ke main features ek jagah jama karti hai. Har column ko upar se neeche padho aur trends dekho: organisation cells se organ systems tak badhta hai, symmetry bilateral par tik jaati hai, aur coelom aur closed circulation aa jaate hain.