Kingdom Animalia | Class 11 Biology | NEET Hinglish Free Notes

1. Basis of Classification

The Animal Kingdom me bohot variety ke animals included hain, from tiny insects se leke large mammals tak. Inhe scientifically study karne ke liye, humein unhe certain characteristics ke basis pe classify karna padta hai. Ye classification humein unke body structure, function, aur evolutionary relationships ko samajhne me help karta hai.

Scientists major criteria use karte hain animals ko classify karne ke liye:

1. Levels of Organization

Animals show different levels of structural organization. These levels indicate how cells are organized into tissues, organs, and systems.

🔹 a. Cellular Level

Seen in sponges (Phylum Porifera).
The animal body is made of loosely arranged cells.
Cells perform different functions but are not organized into tissues.

🔹 b. Tissue Level

Found in Cnidarians (Phylum Coelenterata).
Cells performing the same function group together to form tissues.
For example, Hydra shows simple muscle and nerve tissues.

🔹 c. Organ Level

Found in Platyhelminthes (flatworms).
Tissues combine hoke organs banate hain jo specific functions perform karte hain.
Example: Digestive system flatworms me well-developed hota hai.

🔹 d. Organ System Level

Found in Annelida to Chordata (from earthworms to humans).
Organs well-developed organ systems banate hain (e.g., digestive, respiratory, circulatory).
Ye systems zyada complexity aur specialization dikhate hain.

2. Symmetry

Symmetry ka matlab hai body parts ka arrangement ek central line ya point ke around.

🔹 a. Asymmetry

Body ko do equal halves me divide nahi kiya ja sakta.
Example: Sponges (Porifera).
Unka body shape irregular hota hai.

🔹 b. Radial Symmetry

Body ko do equal halves me divide kiya ja sakta hai through any plane jo central axis se guzarta ho.
Seen in animals like Cnidaria (Hydra, Jellyfish) aur Echinoderms (Sea stars) (adult form me).
Ye symmetry sessile ya slow-moving animals ke liye suitable hai.

🔹 c. Bilateral Symmetry

Body ko do equal halves me divide kiya ja sakta hai sirf ek plane me (left aur right sides).
Found in most advanced animals (from Platyhelminthes to Chordates).
Ye streamlined movement aur better coordination me help karta hai.

3. Germ Layer Organization (Diploblastic vs. Triploblastic)

During embryonic development, animals layers banate hain jinhe germ layers kehte hain, jo baad me different tissues aur organs me develop hote hain.

🔹 a. Diploblastic Animals

Body develop hota hai two germ layers se:
- Ectoderm (outer)
- Endoderm (inner)
Unke beech me non-cellular mesoglea present hoti hai.
Found in Cnidarians (Hydra, Jellyfish).

🔹 b. Triploblastic Animals

Body develop hota hai three germ layers se:
- Ectoderm
- Mesoderm (middle)
- Endoderm
Mesoderm se muscles, skeleton, blood, etc. develop hote hain.
Found in Platyhelminthes to Chordata (i.e., most animals).

4. Coelom (Body Cavity)

The coelom ek fluid-filled space hai body wall aur internal organs ke beech.
Ye independent movement of organs aur better organ development allow karta hai.

🔹 a. Acoelomates

No coelom (body cavity).
Space body wall aur gut ke beech solid tissue se filled hoti hai.
Found in Platyhelminthes (e.g., flatworms).

🔹 b. Pseudocoelomates

Body cavity fully mesoderm se lined nahi hoti.
Mesoderm scattered hota hai ectoderm aur endoderm ke beech.
Found in Aschelminthes (roundworms) like Ascaris.

🔹 c. Coelomates (True Coelom)

Coelom completely mesoderm se lined hota hai..
Organs cavity me suspended hote hain aur mesodermal linings se protected hote hain.
Found in Annelids, Molluscs, Arthropods, Echinoderms, and Chordates.

5. Segmentation (Metamerism)

Segmentation ka matlab hai body ka repeated units (segments) me division.
Ye movement aur specialization of body parts me help karta hai.

🔹 a. No Segmentation

Body segments me divided nahi hoti.
Example: Platyhelminthes, Nematodes, Molluscs.

🔹 b. True Segmentation

Body clearly repeating segments me divided hoti hai, externally aur internally dono.
Found in Annelids (earthworm), Arthropods (insects), and Chordates (vertebral column in humans).
Isse metameric segmentation kehte hain.

🔹 c. Pseudosegmentation

Segments appear repeated hain, lekin real ya internally divided nahi hote.
Example: Tapeworm (Taenia).

6. Notochord

Notochord ek flexible, rod-like structure hai jo embryonic stage me sabhi chordates me present hota hai.
Ye support aur structure provide karta hai.

🔹 Characteristics of Notochord:

Notochord nerve cord aur gut ke beech hota hai.
Ye ek primitive backbone ka kaam karta hai.
Kuch animals me life bhar present rehta hai, aur dusron me vertebral column se replace ho jata hai.

🔹 Classification Based on Notochord:

Type of Animal	Notochord Status
Non-chordates	Absent
Chordates	Kam se kam embryonic stage me present hota hai.
Urochordates	Notochord sirf larval tail me hota hai.
Cephalochordates	Notochord poore jeevan bhar present rehta hai.
Vertebrates	Notochord ko vertebral column (backbone) se replace kar diya jata hai.

2. Phylums Of Kingdom Animalia or Animal Kingdom

Kingdom Animalia ko in phylums me divide kiya gaya hai:-

Phylum Porifera
Phylum Coelenterata (also called Cnidaria)
Phylum Ctenophora
Phylum Platyhelminthes
Phylum Aschelminthes
Phylum Annelida
Phylum Arthropoda
Phylum Mollusca
Phylum Echinodermata
Phylum Hemichordata
Phylum Chordata
- Class Cyclostomata
- Class Chondrichthyes
- Class Osteichthyes
- Class Amphibia
- Class Reptilia
- Class Aves
- Class Mammalia

2.1 Porifera: The Sponge Group

Phylum Porifera me wo animals aate hain jo commonly sponges ke naam se jaane jaate hain. Ye animals mostly samundar me paye jaate hain aur usually asymmetrical hote hain, matlab inka body do equal halves me divide nahi ho sakta. Sponges bahut simple hote hain aur inhe primitive multicellular organisms mana jaata hai. Ye cellular level of organisation dikhate hain, matlab inka body loosely arranged cells se bana hota hai, lekin koi tissue ya organ system nahi hota. Sponges ka ek unique feature unka canal system ya water transport system hai. Paani inke body me chhoti pores ke through enter karta hai jo surface par ostia kehlate hain. Ye paani ek central cavity me jaata hai jo spongocoel kehlati hai, aur fir ek bade opening ke through bahar nikalta hai jo osculum kehlata hai. Ye constant flow of paani food collect karne, gases exchange karne ke liye respiration me, aur waste remove karne me help karta hai. Canal system ki inner lining me special cells hote hain jo choanocytes ya collar cells kehlate hain. Ye food particles trap karne me help karte hain. Food ka digestion cells ke andar hota hai (intracellular digestion). Sponge ka body ya to spicules ya spongin fibres se supported hota hai, jo ek basic internal skeleton banate hain. Sponges usually hermaphrodites hote hain, matlab wahi individual dono eggs aur sperms produce karta hai. Ye do tariko se reproduce kar sakte hain: asexual reproduction by fragmentation (tukdo me break hoke naye individuals me grow karna), aur sexual reproduction by formation of gametes. Sexual reproduction me fertilisation body ke andar hota hai (internal fertilisation), aur new organism ka development ek larval stage se guzarta hai, jo adult se bilkul alag dikhta hai (is process ko indirect development kehte hain).

Common examples of sponges hain Sycon (jo Scypha ke naam se bhi jaana jaata hai), Spongilla (freshwater sponge), aur Euspongia (jo bath sponge ke naam se bhi jaana jaata hai).

2.2 Phylum Coelenterata (Jellyfish and Corals)

Phylum Cnidaria, jo Coelenterata ke naam se bhi jaana jaata hai, me aquatic organisms aate hain jo mostly marine hote hain aur ya to sessile (fixed) hote hain ya free-swimming. Ye animals radial symmetry dikhate hain, matlab inka body multiple planes ke through central axis se similar halves me divide ho sakta hai. Ye diploblastic hote hain, matlab inke do germ layers hote hain—ectoderm aur endoderm—aur inke beech me jelly-like mesoglea hota hai. Body tissue level par organized hota hai, aur inke paas ek central gastrovascular cavity hoti hai jiska ek single opening hota hai jo mouth aur anus dono ka kaam karta hai, aur ye ek raised structure hypostome par located hota hai.

Cnidarians ka ek sabse distinguishing feature hai specialized cells jo cnidoblasts ya cnidocytes kehlate hain, jinme nematocysts (stinging capsules) hote hain jo prey capture, defense, aur attachment me help karte hain. Digestion dono tarah se hota hai—extracellular (gastrovascular cavity me) aur intracellular (cells ke andar). Kuch cnidarians, jaise corals, calcium carbonate se exoskeletons secrete karte hain. Ye do basic body forms me paye jaate hain—polyp (sessile aur cylindrical, jaise Hydra, Adamsia) aur medusa (umbrella-shaped aur free-swimming, jaise Aurelia ya jellyfish). Kuch cnidarians jaise Obelia alternation of generations (ya metagenesis) dikhate hain, jisme asexual polyps se sexual medusae develop hote hain, aur vice versa.

Common examples of cnidarians hain Physalia (Portuguese man-of-war), Adamsia (sea anemone), Pennatula (sea pen), Gorgonia (sea fan), aur Meandrina (brain coral).

2.3 Marine Animals: Phylum Ctenophora

Phylum Ctenophora, commonly known as sea walnuts ya comb jellies, me exclusively marine organisms aate hain jo radially symmetrical aur diploblastic hote hain, aur inka body soft, transparent, aur gelatinous hota hai. Ye tissue-level organization dikhate hain aur body structure me cnidarians se kaafi similar hote hain, lekin inme cnidoblasts nahi hote. Inka ek unique feature hai eight external rows of ciliated comb plates, jo body ke around radially arranged hote hain aur coordinated manner me beat karte hain, jo locomotion me help karta hai. Ye characteristic ctenophores ko sirf un animals me se ek banata hai jo locomotion ke liye cilia ka use apna primary mode of movement ke liye karte hain. Digestion ctenophores me dono tarah hota hai—extracellular aur intracellular.

Kai ctenophores ka ek striking feature hai bioluminescence, yani natural ability to emit light, jo aksar paani me glowing flashes ke roop me dekha jaata hai.

Cnidarians ke unlike, ctenophores hermaphroditic hote hain, matlab sexes separate nahi hote aur har individual dono eggs aur sperm produce karta hai. Reproduction sexually hota hai, with external fertilization. Inka development indirect hota hai, jisme ek larval stage hota hai pehle adult banne se. Ye alternation of generations exhibit nahi karte.

Examples of ctenophores me Pleurobrachia aur Ctenoplana shamil hain.

2.4 Phylum Platyhelminthes: Flat-bodied Worms

Phylum Platyhelminthes me wo organisms aate hain jo commonly flatworms ke naam se jaane jaate hain, kyunki inke bodies dorsoventrally flattened hote hain. Ye animals mostly parasitic hote hain, aur hosts jaise humans aur animals ke andar rehte hain. Ye bilateral symmetry dikhate hain aur triploblastic hote hain, matlab inke teen embryonic layers hote hain: ectoderm, mesoderm, aur endoderm. Lekin ye acoelomate hote hain, matlab inke paas true body cavity nahi hoti. Inke bodies organ level par organized hote hain, aur kai parasitic forms ke paas hooks aur suckers hote hain jo host ke internal organs se attach karne me help karte hain. Kuch species ka ek unique adaptation ye hai ki ye nutrients directly apni body surface se absorb kar sakte hain, especially parasitic types jaise Taenia.

Excretory system me special cells hote hain jo flame cells kehlate hain, jo osmoregulation aur excretion me help karte hain. Reproduction mostly sexual hota hai, aur zyadatar species hermaphrodites hote hain, matlab dono male aur female reproductive organs hote hain. Fertilization internal hoti hai, aur development indirect hota hai, aksar ek ya zyada larval stages involve karte hain. Kuch free-living members jaise Planaria me remarkable ability hoti hai regeneration ki.

Examples of Platyhelminthes me Taenia (tapeworm) aur Fasciola (liver fluke) shamil hain, jo humans me medically important parasites hain.

2.5 Phylum Aschelminthes: Pseudocoelomate Worms

Phylum Aschelminthes, commonly referred to as roundworms, me wo animals aate hain jinke bodies cylindrical in cross-section hote hain, isliye ye naam diya gaya. Ye organisms ya to free-living ho sakte hain aquatic ya terrestrial habitats me, ya phir parasitic plants aur animals me. Ye organ-system level of body organisation dikhate hain, matlab inke organ systems well-developed hote hain specific functions perform karne ke liye.

Roundworms bilaterally symmetrical, triploblastic (teen germ layers wale), aur pseudocoelomate hote hain, matlab inke paas body cavity hoti hai jo completely mesoderm se lined nahi hoti. Alimentary canal complete hota hai, mouth se start hokar anus par end hota hai, aur isme well-developed muscular pharynx hota hai jo food intake me help karta hai. Excretion ek specialized excretory tube ke through hoti hai, jo waste ko excretory pore se discharge karta hai.

Ye animals dioecious hote hain (sexes separate hote hain), jisme distinct male aur female individuals hote hain, aur females aksar males se badi hoti hain. Fertilisation internal hoti hai, aur development ya to direct hota hai, jisme young adults jaise hote hain, ya indirect, jisme ek larval stage involve hota hai.

Common examples of this phylum me Ascaris (roundworm), Wuchereria (filaria worm), aur Ancylostoma (hookworm) shamil hain – jo sab medically significant hain aur aksar NEET-based zoology questions me aate hain.

2.6 Phylum Annelida: Metamerically Segmented Worms

Phylum Annelida me wo animals aate hain jo water me reh sakte hain, dono marine aur freshwater, ya phir land par. Ye animals mostly free-living hote hain, lekin kuch parasitic bhi ho sakte hain. Inka body organ-system level of body organization dikhata hai aur ye bilateral symmetry dikhate hain, matlab inka body do equal halves me divide ho sakta hai.

Annelids triploblastic hote hain, matlab inke body me teen layers of cells hoti hain, aur inke bodies multiple parts me segmented hote hain jise metameres kehte hain. Ye segmentation unke body surface par clearly visible hoti hai, isliye ye Annelida kehlate hain, jo Latin word ‘annulus’ se derived hai, matlab little ring. Inke paas dono longitudinal aur circular muscles hote hain jo movement me help karte hain. Kuch aquatic annelids jaise Nereis ke side appendages hote hain jo parapodia kehlate hain aur swimming me help karte hain.

Ye closed circulatory system possess karte hain jahan blood vessels ke andar flow karta hai. Excretion aur water balance maintain karne ke liye, inke paas nephridia hote hain. Inka nervous system paired ganglia se bana hota hai jo lateral nerves ke through double ventral nerve cord se connected hote hain. Reproduction ke terms me, aquatic annelids jaise Nereis me separate sexes hote hain (dioecious), jabki earthworms aur leeches me dono male aur female reproductive organs ek hi individual me hote hain (monoecious). Reproduction sexual hoti hai.

Common examples of annelids me Nereis, Earthworm (Pheretima), aur blood-sucking leech (Hirudinaria) shamil hain.

2.7 Phylum Arthropoda: Jointed-Limbed Animals

Phylum Arthropoda animal kingdom ka sabse bada phylum hai aur isme insects shamil hain. Earth par naamit species ka do-thirds se zyada is group me belong karte hain. Arthropods ka body organ-system level of organization dikhata hai aur ye bilateral symmetry dikhate hain. Ye triploblastic, segmented, aur coelomate animals hote hain. Inke bodies ek hard chitinous exoskeleton se covered hote hain jo protection aur support provide karta hai. Body teen main parts me divided hota hai: head, thorax, aur abdomen.

Inke paas jointed appendages hote hain (word “arthro” ka matlab joint aur “poda” ka matlab appendages), jo movement aur objects handle karne me help karte hain. Inke respiratory organs species ke hisaab se vary karte hain aur isme gills, book gills, book lungs, ya tracheal system shamil hote hain. Arthropods ka open circulatory system hota hai, jisme blood body cavities me freely flow karta hai. Inke sensory organs well-developed hote hain aur isme antennae, compound aur simple eyes, aur statocysts shamil hote hain jo balance me help karte hain. Excretion ke liye ye malpighian tubules ka use karte hain. Zyadatar arthropods dioecious hote hain (separate sexes ke saath), internal fertilization hoti hai, aur mostly ye oviparous hote hain (eggs lay karte hain). Inka development species ke hisaab se direct ya indirect ho sakta hai.

Kuch important examples me economically valuable insects jaise Apis (Honey bee), Bombyx (Silkworm), aur Laccifer (Lac insect); disease vectors jaise Anopheles, Culex, aur Aedes (mosquitoes); gregarious pest Locusta (Locust); aur living fossil Limulus (King crab) shamil hain.

2.8 Soft-bodied Animals (Phylum Mollusca)

Phylum Mollusca animal kingdom ka second largest phylum hai aur isme wo animals aate hain jo ya to land (terrestrial) ya water (marine ya freshwater) me reh sakte hain. Molluscs ka body organ-system level of organization dikhata hai aur ye bilateral symmetry dikhate hain. Ye triploblastic aur coelomate animals hote hain. Inka body usually ek hard calcareous shell se covered hota hai aur unsegmented hota hai, jisme ek distinct head, ek muscular foot movement ke liye, aur ek soft rounded part visceral hump hota hai. Visceral hump ke upar ek soft, spongy layer of skin hoti hai jo mantle kehlati hai. Mantle aur visceral hump ke beech ka space mantle cavity kehlata hai, jo feather-like gills contain karta hai jo respiration aur excretion dono me help karte hain.

Head ke front part me sensory tentacles hote hain jo environment detect karne me help karte hain. Inke mouth me ek special rasping organ hota hai jo radula kehlata hai, ye file jaisa hota hai aur food scrape karke feeding me help karta hai. Molluscs usually dioecious (separate sexes) aur oviparous (eggs lay karte hain) hote hain, aur inka development indirect hota hai, matlab young larval stages se guzarte hain pehle adult banne se.

Common examples me Pila (Apple snail), Pinctada (Pearl oyster), Sepia (Cuttlefish), Loligo (Squid), aur Octopus (Devil fish), Aplysia (Sea hare), Dentalium (Tusk shell), and Chaetopleura (Chiton) bhi shamil hain.

2.9 Spiny-Skinned Animals (Phylum Echinodermata)

Phylum Echinodermata me wo animals aate hain jinke paas ek internal skeleton hota hai jo endoskeleton kehlata hai, aur ye chhoti calcareous (calcium-based) plates se bana hota hai jo ossicles kehlate hain, jo inka body spiny banate hain, isliye naam Echinodermata ka matlab hai “spiny skin.” Sabhi echinoderms marine environment me rehte hain aur inka body organ-system level of organization dikhata hai. Jabki adult echinoderms radial symmetry dikhate hain (body parts central axis ke around arranged hote hain), unke larvae bilaterally symmetrical hote hain. Ye triploblastic aur coelomate animals hote hain. Inka digestive system complete hota hai, jisme mouth lower (ventral) side par aur anus upper (dorsal) side par hota hai.

Echinoderms ka ek important aur unique feature water vascular system hai, jo movement, food capture and transport, aur respiration me use hota hai. Inke paas alag se excretory system nahi hota.

Sexes separate hote hain, aur reproduction sexual hoti hai external fertilization ke saath. Inka development indirect hota hai, matlab young ek free-swimming larval stage se guzarte hain pehle adult banne se.

Common examples me Asterias (Starfish), Echinus (Sea urchin), Antedon (Sea lily), Cucumaria (Sea cucumber), aur Ophiura (Brittle star) shamil hain.

2.10 hylum Hemichordata: Proboscis, Collar, and Trunk Animals

Phylum Hemichordata pehle sub-phylum ke roop me Chordata ke under consider kiya jaata tha, lekin ab ise non-chordates me ek separate phylum ke roop me recognize kiya gaya hai. Hemichordates worm-like marine animals hote hain aur inka body organ-system level of organization dikhata hai. Ye bilateral symmetry dikhate hain, triploblastic, aur coelomate hote hain. Inka body cylindrical hota hai aur teen parts me divided hota hai: ek anterior proboscis, ek collar, aur ek lamba trunk.

Hemichordates ka ek unique feature hai rudimentary structure jo collar me hota hai aur ise stomochord kehte hain, jo notochord jaise hota hai jo chordates me paya jaata hai. Inka open circulatory system hota hai aur respiration gills ke through hoti hai. Inka excretory organ proboscis gland kehlaata hai. Sexes separate hote hain, fertilization external hoti hai, aur development indirect hota hai, matlab larvae free-swimming stages se guzarte hain pehle mature hone se.

Examples me Balanoglossus aur Saccoglossus shamil hain.

2.11 Phylum Chordata

Phylum Chordata mainly notochord, dorsal hollow nerve cord, aur paired pharyngeal gill slits ki presence se characterized hai. Ye animals bilateral symmetry dikhate hain, triploblastic, coelomate, aur organ-system level of organization wale hote hain. Inke paas post-anal tail aur closed circulatory system bhi hota hai. Phylum Chordata teen subphyla me divided hai: Urochordata (Tunicata), Cephalochordata, aur Vertebrata. Pehle do subphyla, Urochordata aur Cephalochordata, ko protochordates kehte hain aur ye exclusively marine environment me rehte hain. Urochordata me notochord sirf larval tail me present hota hai, jabki Cephalochordata me ye head se tail tak extend karta hai aur life ke dauran persist karta hai. Examples of Urochordata me Ascidia, Salpa, aur Doliolum shamil hain, jabki Branchiostoma (Amphioxus ya Lancelet) Cephalochordata ko represent karta hai.

Subphylum Vertebrata ke members embryonic development ke dauran notochord rakhte hain, jo adults me vertebral column se replace ho jaata hai, jo cartilage ya bone se bana hota hai. Matlab, sab vertebrates chordates hain, lekin sab chordates vertebrates nahi hote. Basic chordate features ke alawa, vertebrates me ventral muscular heart hota hai jisme do, teen, ya char chambers hote hain, kidneys excretion aur osmoregulation ke liye, aur paired appendages jaise fins ya limbs hote hain.

Class Cyclostomata

Class Cyclostomata me wo living animals aate hain jo kuch fishes ke upar ectoparasites hote hain. Inka body elongated hota hai aur inke paas 6 se 15 pairs of gill slits hote hain jo respiration ke liye use hote hain. Cyclostomes ka circular, sucking mouth hota hai bina jaws ke, jo inhe host se attach karne me help karta hai. Inke bodies me scales aur paired fins nahi hote. Inka cranium aur vertebral column cartilage se bana hota hai, bone se nahi. Inka closed circulatory system hota hai.

Cyclostomes mainly marine environments me rehte hain, lekin spawn karne ke liye freshwater migrate karte hain. Spawning ke baad ye kuch hi din me mar jaate hain. Inke larvae metamorphosis undergo karte hain aur phir ocean me return karte hain.

Examples of this class me Petromyzon (Lamprey) aur Myxine (Hagfish) shamil hain.

Class Chondrichthyes

Class Chondrichthyes me wo marine animals aate hain jinka body streamlined hota hai aur inka endoskeleton cartilaginous hota hai, matlab inka internal skeleton cartilage se bana hota hai, bone se nahi. Inka mouth ventral (lower) side par hota hai. Inka notochord life bhar present rehta hai. Inke paas kai separate gill slits hote hain lekin operculum (gill cover) nahi hota. Inki skin tough hoti hai aur tiny placoid scales se covered hoti hai. Ye scales modify hoke sharp, backward-pointing teeth ban jaate hain jo inke jaws ko bahut powerful banate hain.

Chondrichthyes predators hote hain aur kyunki inke paas air bladder nahi hota jo buoyancy me help kare, ye constantly swimming karte rahte hain taaki doob na jaaye. Inka heart two chambers ka hota hai (ek auricle aur ek ventricle). Kuch species ke paas special electric organs hote hain (jaise Torpedo fish), aur kuch ke paas poisonous stings hote hain (jaise Trygon ya stingray). Ye animals cold-blooded (poikilothermic) hote hain, matlab ye apna body temperature regulate nahi kar sakte.

Sexes separate hote hain, aur males ke pelvic fins par claspers hote hain jo reproduction me use hote hain. Fertilization internal hoti hai, aur kai species viviparous hote hain, matlab live young ko janam dete hain.

Examples me Scoliodon (Dog fish), Pristis (Saw fish), Carcharodon (Great white shark), aur Trygon (Sting ray) shamil hain.

Class Osteichthyes

Class Osteichthyes me dono marine aur freshwater fishes aate hain jinke paas bony endoskeleton hota hai. Inke bodies streamlined hote hain taaki water me easily move kar sake. Inka mouth mostly terminal hota hai, matlab head ke front me located hota hai. Inke paas four pairs of gills hote hain, jise operculum naam ke protective flap se cover kiya hota hai. Inki skin cycloid ya ctenoid scales se covered hoti hai jo protection provide karti hain.

Osteichthyes ke paas air bladder (swim bladder) hota hai jo buoyancy regulate karne me help karta hai, jisse ye different water depths me float kar sakte hain. Inka heart two chambers ka hota hai—ek auricle aur ek ventricle. Ye fishes cold-blooded hote hain, matlab ye apna body temperature internally regulate nahi kar sakte. Sexes separate hote hain, aur fertilization mostly external hoti hai. Zyadatar oviparous hote hain (egg-laying), aur inka development direct hota hai, matlab young adults ke chhote versions ke roop me hatch hote hain.

Examples me marine fishes jaise Exocoetus (Flying fish) aur Hippocampus (Sea horse); freshwater fishes jaise Labeo (Rohu), Catla (Katla), aur Clarias (Magur); aur popular aquarium fishes jaise Betta (Fighting fish) aur Pterophyllum (Angel fish) shamil hain.

Class Amphibia

Class Amphibia me wo animals aate hain jo dono aquatic (water) aur terrestrial (land) habitats me reh sakte hain, isliye inka naam ka matlab hai “dual life.” Zyadatar amphibians ke paas do pairs of limbs hote hain. Inka body head aur trunk me divided hota hai, aur kuch species me tail bhi hota hai. Inki skin moist aur scaleless hoti hai, jo respiration through skin me help karti hai. Inki eyes ke paas eyelids hote hain aur ek hearing structure hota hai jo tympanum (eardrum) kehlata hai.

Inka alimentary canal, urinary, aur reproductive systems ek common chamber me open hote hain jo cloaca kehlata hai, aur ye bahar ki taraf open hota hai. Amphibians gills, lungs, aur skin ke through breathe karte hain. Inka heart three chambers ka hota hai—two auricles aur one ventricle. Ye cold-blooded animals hote hain, matlab apna body temperature internally regulate nahi kar sakte. Sexes separate hote hain, fertilization usually external hoti hai, aur ye oviparous (egg-laying) hote hain. Inka development indirect hota hai, matlab larval stage se guzarte hain pehle adult banne se.

Examples me Bufo (Toad), Rana (Frog), Hyla (Tree frog), Salamandra (Salamander), aur Ichthyophis (Limbless amphibian) shamil hain.

Class Reptilia

Class Reptilia me wo animals aate hain jo apni creeping ya crawling movement ke liye jane jaate hain, isliye inka naam Latin word se aaya hai jiska matlab hai “to creep.” Zyadatar reptiles terrestrial hote hain aur inke bodies dry, cornified skin se covered hote hain jo epidermal scales ya scutes se bana hota hai. Inke paas external ear openings nahi hote, lekin ek tympanum hota hai jo ear ki tarah function karta hai. Jab limbs present hote hain, reptiles ke paas two pairs hote hain.

Inka heart usually three chambers ka hota hai, except crocodiles, jinke paas four-chambered heart hota hai. Reptiles poikilotherms (cold-blooded) hote hain, matlab ye apna internal body temperature regulate nahi kar sakte. Snakes aur lizards apni skin periodically shed karte hain. Sexes separate hote hain, fertilization internal hoti hai, aur reptiles mostly oviparous (egg-laying) hote hain with direct development.

Examples me Chelone (Turtle), Testudo (Tortoise), Chameleon (Tree lizard), Calotes (Garden lizard), Crocodilus (Crocodile), Alligator (Alligator), Hemidactylus (Wall lizard), aur poisonous snakes jaise Naja (Cobra), Bangarus (Krait), aur Vipera (Viper) shamil hain.

Class Aves (birds)

Class Aves (birds) mainly feathers ki presence se characterized hain, aur zyadatar birds fly kar sakte hain, except kuch flightless birds jaise Ostrich. Inke paas teeth ki jagah beak hota hai. Inke forelimbs wings me modified hote hain jo flying ke liye use hote hain, jabki hind limbs usually scales se covered hote hain aur walking, swimming, ya tree branches grasping ke liye adapted hote hain. Inki skin dry hoti hai aur glands nahi hote, except ek oil gland jo tail ke base me hoti hai aur feather condition maintain karne me help karti hai.

Birds ka fully ossified (bony) endoskeleton hota hai, jisme hollow long bones hote hain jo air cavities (pneumatic bones) se filled hote hain taaki weight kam ho aur flying easy ho. Inka digestive system special chambers like crop aur gizzard include karta hai jo food storage aur grinding ke liye hote hain. Inka heart completely four-chambered hota hai, jo oxygenated aur deoxygenated blood ko efficiently separate karta hai.

Birds warm-blooded (homoiothermic) hote hain, matlab ye apna body temperature constant maintain karte hain. Respiration lungs ke through hoti hai, jo air sacs se supplemented hoti hain, jo breathing efficiency improve karte hain. Sexes separate hote hain, fertilization internal hoti hai, aur birds oviparous (egg-laying) hote hain with direct development.

Examples me Corvus (Crow), Columba (Pigeon), Psittacula (Parrot), Struthio (Ostrich), Pavo (Peacock), Aptenodytes (Penguin), aur Neophron (Vulture) shamil hain.

Class Mammalia

Class Mammalia me wo animals aate hain jo wide range of habitats me paye jaate hain jaise polar ice caps, deserts, mountains, forests, grasslands, aur dark caves. Kuch mammals ne fly karne ya water me rehne ke liye adapt kiya hai. Mammals ka sabse distinctive feature hai mammary glands, jo milk produce karte hain taaki young ones nourish ho sake.

Mammals ke paas two pairs of limbs hote hain jo different activities ke liye adapted hote hain jaise walking, running, climbing, burrowing, swimming, ya flying. Inki skin unique hoti hai kyunki isme hair hota hai. Inke paas external ears (pinnae) hote hain, aur jaws me different types ke teeth hote hain jo various functions ke liye use hote hain. Mammalian heart four-chambered hota hai jo efficient blood circulation support karta hai.

Mammals homoiothermic (warm-blooded) hote hain, matlab ye constant body temperature maintain karte hain. Ye lungs ke through breathe karte hain. Sexes separate hote hain, fertilization internal hoti hai, aur zyadatar mammals viviparous (give birth to live young) hote hain, lekin kuch exceptions bhi hain. Inka development direct hota hai, matlab young adults ke similar form me born hote hain.

Examples me oviparous jaise Platypus (Ornithorhynchus); aur viviparous animals jaise Macropus (Kangaroo), Pteropus (Flying fox), Camelus (Camel), Macaca (Monkey), Rattus (Rat), Canis (Dog), Felis (Cat), Elephas (Elephant), Equus (Horse), Delphinus (Common dolphin), Balaenoptera (Blue whale), Panthera tigris (Tiger), aur Panthera leo (Lion) shamil hain.

2.2 Summury

The animal kingdom broadly classify kiya gaya hai fundamental features ke basis par jaise level of organization, symmetry, cell organization, coelom, segmentation, aur presence of a notochord. Har phylum ya class ke apne unique characteristics hote hain.

Porifera multicellular animals hain jinke paas cellular level of organization hota hai aur special cells hote hain jo choanocytes kehlate hain. Coelenterates ke tentacles me stinging cells (cnidoblasts) hote hain aur ye mostly aquatic, ya to fixed ya free-floating hote hain. Ctenophores marine animals hote hain jinke paas comb plates movement ke liye hote hain. Platyhelminths ka body flat hota hai aur ye bilateral symmetry dikhate hain; inke parasitic forms me suckers aur hooks hote hain. Aschelminthes pseudocoelomates hote hain aur ye parasitic aur non-parasitic roundworms include karte hain. Annelids ka body segments me divided hota hai (metameric segmentation) aur inka true coelom hota hai. Arthropods largest group hain jinke paas jointed appendages aur external skeleton (chitin) hota hai. Molluscs ka body soft hota hai aur calcareous shell se covered hota hai. Echinoderms ke paas spiny skin aur unique water vascular system hota hai. Hemichordates worm-like marine animals hain jinka body proboscis, collar, aur trunk me divided hota hai.

Chordates ke paas life ke kuch part me notochord, dorsal hollow nerve cord, aur paired pharyngeal gill slits hote hain. Chordates me, Agnatha (jawless fishes) class Cyclostomata se represent hote hain, jo primitive ectoparasites hain fishes par. Gnathostomata (jawed vertebrates) do superclasses me divided hain: Pisces aur Tetrapoda. Chondrichthyes aur Osteichthyes fishes hain jinke paas fins hote hain aur ye Pisces me aate hain; Chondrichthyes ka cartilaginous skeleton hota hai aur ye sea me rehte hain.

Tetrapods, jinke paas two pairs of limbs hote hain, include karte hain Amphibia, Reptilia, Aves, aur Mammalia. Amphibians dono land aur water me rehte hain, jabki reptiles ka dry, cornified skin hota hai aur snakes me limbs nahi hote. Fish, amphibians, aur reptiles cold-blooded (poikilotherms) hote hain. Birds (Aves) warm-blooded hote hain, inke paas feathers hote hain, forelimbs wings me modified hote hain, aur hind limbs walking, swimming, ya perching ke liye adapted hote hain. Mammals unique hain kyunki inke paas mammary glands aur hair hota hai, aur zyadatar viviparous hote hain (live young ko janam dete hain).

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