animal kingdom ncert notes

ANIMALS IN KINGDOM

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जब हम अपने चारों ओर देखते हैं तो हम विभिन्न animal के विभिन्न structure और form को observe करते हैं।

अब तक लगभग 10 लाख से अधिक animal species का वर्णन किया जा चुका है। अतः classification इसके लिए अधिक महत्त्वपूर्ण आधार है।

Classification नयी खोजी गयी species को systematic position पर रखने में सहायता प्रदान करता है।

4.1 Basis of Classification

Animals में structure और form में भिन्नताओं के अलावा भी उनमें arrangement of cell, body symmetry, nature of coelom, pattern of digestive, circulatory या reproductive system में fundamental समानता पाई जाती है।

इन्हीं लक्षणों को हम animal classification का आधार मानते हैं और इनमें से कुछ का वर्णन यहाँ किया जा रहा है।

4.1.1 Levels of Organisation

Animal kingdom के सभी सदस्य multicellular होते हैं, लेकिन सभी same pattern के cells organisation को प्रदर्शित नहीं करते। उदाहरण:

Cellular Level of Organisation
Characteristics	इनमें cells का arrangement अधिक loose होता है; जैसे sponges में। Cell के मध्य कुछ division of labour पाया जाता है।

animal kingdom ncert notes

Tissue Level of Organisation
Characteristics	इसमें cells का arrangement अधिक complex होता है। एक समान कार्य करने वाली cells मिलकर tissue का निर्माण करती हैं; जैसे coelenterates।

animal kingdom ncert notes

Organ Level of Organisation

Characteristics

Tissues मिलकर organs का निर्माण करते हैं और प्रत्येक organ एक particular कार्य करता है। यह Platyhelminthes तथा अन्य higher phyla में पाया जाता है। Animals जैसे annelids, arthropods, molluscs, echinoderms, और chordates में organs मिलकर organ system बनाते हैं। प्रत्येक organ system अलग-अलग physiological function करता है। Incomplete digestive system: Platyhelminthes में केवल एक opening होती है। Complete digestive system: दो openings होती हैं: mouth और anus। Circulatory system: Open type: blood, heart द्वारा pump होता है। Cells और tissues सीधे blood के सम्पर्क में रहते हैं। Closed type: blood vessels (arteries, veins, capillaries) से बहता है।

 

4.1.2 Symmetry

Animal को symmetry के आधार पर categorised किया जाता है।

Asymmetrical
Definition	Body को किसी भी central axis से गुजरने वाली line द्वारा दो बराबर भागों में विभाजित नहीं किया जा सकता।
Example	Sponges mostly asymmetrical होते हैं।

animal kingdom ncert notes

Radial Symmetry
Definition	किसी भी central axis से गुजरने वाली line प्राणी के शरीर को दो समरूप भागों में divide करती है। इसे अरीय सममिति कहते हैं।
Example	Coelenterates, Ctenophore, Echinoderms

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Diploblastic और Triploblastic Organisation

Animals के embryonic development के आधार पर उन्हें Diploblastic और Triploblastic में classify किया जाता है। यह classification germ layers की संख्या पर आधारित है।

Diploblastic Organisation
Definition	ऐसे animals जिनमें केवल दो primary germ layers पाई जाती हैं।
Germ Layers	Ectoderm: बाहरी layer जो skin और nervous system बनाती है। Endoderm: आंतरिक layer जो digestive tract और associated glands बनाती है।
Mesoderm	Absent (मध्य layer नहीं होती)।
Body Cavity	Coelom नहीं होता (acoelomate)।
Examples	Coelenterates (Cnidaria), Ctenophora
Body Symmetry	Mostly radial symmetry, कुछ asymmetric भी हो सकते हैं।

 

Triploblastic Organisation
Definition	ऐसे animals जिनमें तीन primary germ layers पाई जाती हैं।
Germ Layers	Ectoderm: बाहरी layer, skin और nervous system बनाती है। Mesoderm: मध्य layer, muscles, skeleton और circulatory system बनाती है। Endoderm: आंतरिक layer, digestive tract और glands बनाती है।
Body Cavity	Coelom present (Coelomate) या pseudocoelomate हो सकते हैं।
Examples	Platyhelminthes, Nematoda, Annelida, Arthropoda, Mollusca, Echinodermata, Chordata
Body Symmetry	Mostly bilateral symmetry।
Complexity	Organ systems well developed; higher physiological functions possible।

 

Summary
Diploblastic	2 germ layers, no mesoderm, radial symmetry, simple body, examples: Cnidaria
Triploblastic	3 germ layers, mesoderm present, bilateral symmetry, complex body, examples: Annelida, Arthropoda, Chordata

 

Coelom (शरीर गुहा)

Coelom एक fluid-filled body cavity है जो triploblastic animals में mesoderm के भीतर स्थित होती है। यह internal organs को support और protection प्रदान करती है।

Coelom के प्रकार

Types of Coelom
Type	Definition	Examples
Acoelomate	Coelom absent; body cavity filled with mesodermal tissue.	Platyhelminthes
Pseudocoelomate	Body cavity partially lined with mesoderm (between endoderm and mesoderm).	Nematoda, Rotifera
Coelomate (Eucoelomate)	True coelom; body cavity completely lined with mesoderm.	Annelida, Arthropoda, Mollusca, Echinodermata, Chordata

 

Coelom के लाभ

Advantages of Coelom
1.	Internal organs के लिए सुरक्षित जगह प्रदान करता है।
2.	Organs के free movement की अनुमति देता है।
3.	Body shape को maintain करने में मदद करता है।
4.	Circulatory और excretory system के लिए स्थान उपलब्ध कराता है।
5.	Hydrostatic skeleton का कार्य करता है, जिससे movement आसान होता है।

 

Summary of Coelom

Coelom Types Summary
Acoelomate	No coelom, mesoderm fills body cavity, example: Platyhelminthes
Pseudocoelomate	Partial coelom, between endoderm and mesoderm, example: Nematoda
Coelomate	True coelom fully lined with mesoderm, example: Annelida, Arthropoda, Chordata

 

Segmentation (Metamerism) – खंडन / Segmentation

Segmentation या Metamerism वह स्थिति है जिसमें animal body को समान आकार और संरचना वाले segments (खंडों) में विभाजित किया जाता है।

विशेषताएँ (Characteristics of Segmentation)

Characteristics
1.	Body longitudinally repeated segments (metameres) में विभाजित होती है।
2.	हर segment में muscles, nerves, excretory structures और coelomic cavity का हिस्सा होता है।
3.	Segments externally similar होते हैं लेकिन internally slightly अलग हो सकते हैं।
4.	Movement अधिक efficient होता है।
5.	Body flexibility और organ specialization में मदद करता है।

 

Segmentation के प्रकार

Type	Definition	Examples
External Segmentation	Segments शरीर की बाहरी सतह पर दिखाई देते हैं।	Earthworm, Leech
Internal Segmentation	Segments शरीर के अंदर coelom, muscles और organs में दिखाई देते हैं।	Annelida, Arthropoda

 

Advantages of Segmentation

Advantages
1.	Movement और locomotion अधिक coordinated और efficient होता है।
2.	Damage होने पर एक segment को नुकसान से बचाया जा सकता है।
3.	Organ specialization की सुविधा मिलती है।
4.	Body flexibility बढ़ती है।

 

Examples of Segmented Animals

Phylum	Examples
Annelida	Earthworm, Leech
Arthropoda	Scorpion, Centipede
Chordata	Vertebral column is segmented (humans, fish)

 

Notochord (नॉटोकॉर्ड) – Animal Kingdom

Notochord एक flexible, rod-like structure है जो Chordates में पाए जाने वाले embryos और कुछ adults में होती है। यह शरीर का मुख्य supporting axis प्रदान करती है।

विशेषताएँ (Characteristics)

Characteristics of Notochord
1.	Flexible, rod-like structure located dorsal to the digestive tract और ventral to nerve cord।
2.	Embryonic support प्रदान करती है।
3.	Mostly made of cells filled with fluid surrounded by sheath of fibrous tissue।
4.	Axial skeleton का primitive form।
5.	In higher vertebrates, adult stage में vertebral column द्वारा replace कर दी जाती है।

 

Functions of Notochord

Functions
1.	Body को flexible support प्रदान करना।
2.	Nervous system (dorsal nerve cord) के लिए structural guide।
3.	Muscle attachment और movement में मदद।
4.	Embryo development में signalling center का कार्य।

 

Occurrence of Notochord

Group	Examples	Stage
Protochordates	Amphioxus (Branchiostoma), Ascidian larva	Adult और Larva
Vertebrates	Fish, Amphibians, Reptiles, Birds, Mammals	Embryo stage में present, adult में replaced by vertebral column

 

Summary

Notochord Summary
Definition	Flexible, rod-like dorsal support structure found in chordates.
Function	Support, muscle attachment, guidance for nervous system, embryonic development.
Occurrence	Protochordates: adult and larva; Vertebrates: embryo stage

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Coelom, Segmentation और Notochord का सारांश

Feature	Definition	Types / Details	Examples	Key Facts
Coelom (शरीर गुहा)	Fluid-filled body cavity, mesoderm के भीतर, internal organs को support करता है।	Acoelomate: Coelom absent Pseudocoelomate: Partially lined Coelomate: True coelom, fully lined	Platyhelminthes (Acoelomate), Nematoda (Pseudocoelomate), Annelida, Arthropoda, Chordata (Coelomate)	Provides space for organ movement, hydrostatic skeleton, body shape maintenance
Segmentation (Metamerism)	Body divided into repeated segments (metameres) along longitudinal axis.	External Segmentation: visible on body surface Internal Segmentation: visible in muscles, coelom, organs	Earthworm, Leech, Scorpion, Centipede, Vertebrates (vertebral column)	Improves movement, flexibility, organ specialization, and damage resistance
Notochord (नॉटोकॉर्ड)	Flexible, rod-like supporting structure along dorsal side of body.	Embryonic support for chordates Mostly replaced by vertebral column in adult vertebrates	Protochordates: Amphioxus, Ascidian larva; Vertebrates: Fish, Amphibians, Reptiles, Birds, Mammals (embryo)	Supports body, provides site for muscle attachment, guides nervous system development

Classification of Animal Kingdom (Compressed)

Phylum	Level of Organisation	Symmetry	Body Cavity / Coelom	Digestive System	Examples
Porifera	Cellular	Asymmetrical	Acoelomate	None (Intracellular digestion)	Sponges
Coelenterata (Cnidaria)	Tissue	Radial	Acoelomate	Incomplete	Hydra, Jellyfish
Platyhelminthes	Organ	Bilateral	Acoelomate	Incomplete	Planaria, Liver fluke
Nematoda	Organ	Bilateral	Pseudocoelomate	Complete	Ascaris, Roundworm
Annelida	Organ System	Bilateral	Coelomate	Complete	Earthworm, Leech
Arthropoda	Organ System	Bilateral	Coelomate	Complete	Insects, Spider, Scorpion
Mollusca	Organ System	Bilateral	Coelomate	Complete	Snail, Octopus
Echinodermata	Organ System	Radial (adult), Bilateral (larva)	Coelomate	Complete	Starfish, Sea urchin
Chordata	Organ System	Bilateral	Coelomate	Complete	Fishes, Amphibians, Reptiles, Birds, Mammals

 

Phylum Porifera (स्पंज)

Phylum Porifera के जीव सबसे primitive multicellular animals हैं। इन्हें “Pore bearing animals” भी कहा जाता है क्योंकि इनके शरीर पर छोटे-छोटे pores (छिद्र) पाए जाते हैं।

विशेषताएँ (Characteristics)

Characteristics of Porifera
Organisation	Cellular level of organisation (tissues absent)
Symmetry	Mostly asymmetrical, कुछ radially symmetrical भी
Body Wall	3 layers: Outer pinacoderm, Middle mesohyl, Inner choanoderm
Skeleton	Spicules (calcareous/siliceous) और spongin fibers
Coelom	Absent (Acoelomate)
Digestive System	Intracellular digestion (choanocytes digest food)
Circulatory & Excretory	Diffusion द्वारा
Nervous & Muscular System	Absent
Reproduction	Asexual: Budding, Fragmentation, Gemmules Sexual: Monoecious, internal fertilization, larva free-swimming (amphiblastula or parenchymula)
Habitat	Mostly marine, some freshwater

Body Structure Types (Morphology)

Body Type	Characteristics
Ascon	Simple tube-like body, small size, choanocytes in spongocoel
Sycon	Body wall folded into radial canals, choanocytes in canals, medium size
Leucon	Most complex, choanocytes in chambers, large size, commonest type

 

Skeleton Types

Type	Material	Example
Calcareous	Calcium carbonate	Sycon, Leucosolenia
Siliceous	Silica	Euplectella, Spongilla
Spongin	Protein fibers	Bath sponge

 

Fun Facts / Quick Facts

Facts About Porifera
1.	Porifera are the only multicellular animals without true tissues.
2.	Sponges can regenerate their whole body from fragments.
3.	Gemmules help freshwater sponges survive harsh conditions.
4.	Most sponges are asymmetrical; some show radial symmetry.
5.	Bath sponges are commercially harvested for cleaning and crafts.

 

Phylum Cnidaria (Coelenterata) – जेलीफ़िश और हाइड्रा जैसे जीव

Phylum Cnidaria (पूर्व में Coelenterata) में soft-bodied, mostly aquatic animals आते हैं। इनका नाम “Cnidocytes” से पड़ा है क्योंकि इनके cells में stinging organelles पाए जाते हैं।

विशेषताएँ (Characteristics)

Characteristics of Cnidaria
Organisation	Tissue level (diploblastic: Ectoderm + Endoderm; Mesoglea in between)
Symmetry	Radial symmetry
Body Wall	Two layers: Epidermis (ectoderm), Gastrodermis (endoderm) with gelatinous mesoglea
Coelom	Absent (Acoelomate)
Digestive System	Incomplete, single opening serves as mouth and anus
Circulatory & Excretory	Diffusion द्वारा
Nervous System	Nerve net, no brain
Reproduction	Asexual: Budding, Fragmentation, Pedal laceration Sexual: Dioecious, external fertilization, planula larva
Habitat	Mostly marine, few freshwater species

 

Body Forms

Body Form	Characteristics	Example
Polyp	Cylindrical, sessile, mouth & tentacles upward	Hydra, Obelia (polyp colony)
Medusa	Umbrella-shaped, free-swimming, mouth & tentacles downward	Jellyfish, Aurelia

 

Special Features

Feature	Description
Cnidocytes	Stinging cells containing nematocysts for defense and prey capture
Mesoglea	Jelly-like non-cellular layer between epidermis and gastrodermis
Hydrostatic Skeleton	Body support is provided by water pressure inside gastrovascular cavity
Nerve Net	Primitive nervous system for coordination of movements

 

Fun / Quick Facts

Facts About Cnidaria
1.	All cnidarians are aquatic, mostly marine.
2.	Diploblastic: no mesoderm, only ectoderm & endoderm.
3.	Have cnidocytes with nematocysts for stinging and defense.
4.	Body has radial symmetry; polyp form is sessile, medusa form is motile.
5.	Reproduce both sexually and asexually; planula larva is free-swimming.

 

Phylum Ctenophora (Comb Jellies) – कंघी जेली

Phylum Ctenophora में marine, transparent, gelatinous animals आते हैं, जिन्हें Comb jellies कहा जाता है। इनके शरीर पर cilia के comb plates पाए जाते हैं जो locomotion में मदद करते हैं।

विशेषताएँ (Characteristics)

Characteristics of Ctenophora
Organisation	Tissue level, diploblastic (Ectoderm + Endoderm) with mesoglea
Symmetry	Biradial or radial symmetry
Coelom	Absent (Acoelomate)
Digestive System	Complete, mouth and anal pores present
Nervous System	Nerve net, statocyst for balance
Locomotion	By 8 rows of ciliary comb plates (ctenes)
Reproduction	Mostly sexual, hermaphrodite, external fertilization
Habitat	Marine, free-swimming

 

Body Structure

Feature	Description
Body Shape	Transparent, gelatinous, elongated or oval
Comb Plates	8 rows of fused cilia for locomotion
Adhesive Tentacles	Used for capturing prey (colloblast cells)
Mesoglea	Thick gelatinous layer between ectoderm and endoderm

 

Fun / Quick Facts

Facts About Ctenophora
1.	Called “comb jellies” because of rows of ciliary plates (ctenes).
2.	Biradial symmetry distinguishes them from cnidarians.
3.	They use colloblasts (sticky cells) instead of cnidocytes to capture prey.
4.	Mostly pelagic, floating freely in the ocean.
5.	Statocyst helps maintain orientation and balance in water.

 

Phylum Platyhelminthes (Flatworms) – फ्लैटवर्म्स

Phylum Platyhelminthes में soft-bodied, bilaterally symmetrical और triploblastic animals आते हैं। ये mostly parasitic या free-living होते हैं। शरीर dorso-ventrally flattened होता है, इसलिए इन्हें Flatworms कहा जाता है।

विशेषताएँ (Characteristics)

Characteristics of Platyhelminthes
Organisation	Organ level; Triploblastic (Ectoderm, Mesoderm, Endoderm)
Symmetry	Bilateral symmetry
Body Cavity	Acoelomate (no true coelom)
Digestive System	Incomplete (single opening serves as mouth and anus), absent in some parasites
Circulatory & Excretory	Diffusion; Protonephridia with flame cells for excretion
Nervous System	Ladder-like with paired cerebral ganglia and longitudinal nerve cords
Reproduction	Hermaphrodite; sexual (internal fertilization) and asexual (regeneration)
Habitat	Freshwater, marine, terrestrial, and parasitic in animals

 

Classification / Classes

Class	Characteristics	Examples
Turbellaria	Free-living, ciliated, mostly aquatic, gut branched	Planaria, Dugesia
Trematoda	Parasitic, suckers for attachment, incomplete digestive system	Fasciola (liver fluke), Clonorchis
Cestoda	Endoparasitic, no digestive system, body in proglottids, scolex for attachment	Taenia (tapeworm), Diphyllobothrium

 

Special Features

Feature	Description
Flame Cells	Excretory cells helping in osmoregulation
Regeneration	Ability to regrow lost parts, especially in Turbellarians
Parasitism Adaptations	Suckers, hooks, thick tegument for protection in Trematoda & Cestoda
Triploblastic	Presence of three germ layers: ectoderm, mesoderm, endoderm

 

Fun / Quick Facts

Facts About Platyhelminthes
1.	Flatworms are the first bilaterally symmetrical animals.
2.	They are acoelomate but triploblastic.
3.	Flame cells help in excretion and osmoregulation.
4.	Some species can regenerate completely from fragments.
5.	Trematodes and Cestodes are important parasites of humans and animals.

 

Phylum Aschelminthes (Nematoda / Roundworms) – राउंडवर्म्स

Phylum Aschelminthes में cylindrical, bilaterally symmetrical, triploblastic और pseudocoelomate animals आते हैं। इनमें कई free-living और parasitic forms पाए जाते हैं।

विशेषताएँ (Characteristics)

Characteristics of Aschelminthes
Organisation	Organ system level; Triploblastic
Symmetry	Bilateral symmetry
Body Cavity	Pseudocoelomate (body cavity partially lined with mesoderm)
Digestive System	Complete, mouth and anus present
Circulatory & Excretory	Diffusion; Excretory canals or renette cells
Nervous System	Dorsal and ventral nerve cords with anterior nerve ring
Reproduction	Sexual, dioecious; internal fertilization
Habitat	Soil, freshwater, marine; many parasitic in plants & animals

 

Important Examples

Type	Host / Habitat	Example
Free-living	Soil / freshwater	Ascaris megalocephala (soil), Turbatrix aceti (vinegar eel)
Parasitic in humans	Intestine	Ascaris lumbricoides, Enterobius vermicularis (pinworm)
Parasitic in animals	Intestine / tissue	Wuchereria bancrofti, Brugia malayi
Parasitic in plants	Roots / stems	Heterodera, Meloidogyne

 

Special Features

Feature	Description
Body	Cylindrical, tapered at both ends, covered by tough cuticle
Pseudocoelom	Acts as hydrostatic skeleton for movement
Muscles	Longitudinal only, no circular muscles; whip-like movement
Reproduction	Dioecious, sexual dimorphism present; females larger

 

Fun / Quick Facts

Facts About Aschelminthes
1.	First group with complete digestive system (mouth and anus separate).
2.	Body covered by cuticle, resistant to host digestive enzymes.
3.	Pseudocoelom acts as hydrostatic skeleton.
4.	Many are medically important parasites (e.g., Wuchereria, Ascaris).
5.	Movement is whip-like due to longitudinal muscles.

 

Phylum Annelida (Segmented Worms) – खंडित कृमि

Phylum Annelida में bilaterally symmetrical, triploblastic और coelomate animals आते हैं। ये segmented worms कहलाते हैं क्योंकि इनका शरीर externally और internally metamerically segmented होता है।

विशेषताएँ (Characteristics)

Characteristics of Annelida
Organisation	Organ system level; Triploblastic
Symmetry	Bilateral symmetry
Body Cavity	Coelomate (true coelom present)
Segmentation	Metamerically segmented; septa separate segments internally
Digestive System	Complete, mouth and anus present; specialized regions (pharynx, intestine)
Circulatory System	Closed type, dorsal and ventral blood vessels with segmental hearts
Excretory System	Nephridia in each segment
Nervous System	Ventral nerve cord, cerebral ganglia, segmental ganglia
Reproduction	Mostly sexual; some hermaphrodites (earthworm), asexual by regeneration in some
Habitat	Marine, freshwater, and terrestrial

 

Classification / Classes

Class	Characteristics	Examples
Polychaeta	Mostly marine, many setae per segment, parapodia present	Nereis, Aphrodite
Oligochaeta	Few setae per segment, no parapodia, terrestrial/freshwater	Earthworm (Lumbricus), Tubifex
Hirudinea	No setae, body flattened dorsoventrally, mostly parasitic (blood-sucking)	Leech (Hirudo medicinalis)

 

Special Features

Feature	Description
Segmentation (Metamerism)	Body divided into segments with repeated organs; allows better locomotion and specialization
Coelom	Acts as hydrostatic skeleton; helps in movement
Closed Circulatory System	Efficient transport of oxygen and nutrients
Nephridia	Segmental excretory organs for removal of nitrogenous waste

 

Fun / Quick Facts

Facts About Annelida
1.	First coelomate animals with metameric segmentation.
2.	Closed circulatory system is highly efficient for active movement.
3.	Earthworms are important for soil aeration and fertility.
4.	Some leeches are used medicinally for bloodletting.
5.	Metamerism allows specialization of segments for reproduction, locomotion, and excretion.

 

Phylum Arthropoda – अर्थ्रोपोडा (Jointed-legged Animals)

Phylum Arthropoda में bilaterally symmetrical, triploblastic और coelomate animals आते हैं। ये सबसे diverse और abundant phylum है। इनका शरीर segmented होता है और jointed appendages पाई जाती हैं।

विशेषताएँ (Characteristics)

Characteristics of Arthropoda
Organisation	Organ system level; Triploblastic
Symmetry	Bilateral symmetry
Body Cavity	Coelomate (true coelom)
Body Segmentation	Metamerically segmented; head, thorax, abdomen
Exoskeleton	Chitinous exoskeleton, molted periodically (ecdysis)
Appendages	Paired, jointed appendages specialized for locomotion, feeding, reproduction
Digestive System	Complete, with mouth, stomach, intestine, anus
Circulatory System	Open type; dorsal heart pumps hemolymph
Excretory System	Green glands or Malpighian tubules depending on class
Nervous System	Ventral nerve cord, brain (cerebral ganglia), segmental ganglia
Reproduction	Mostly sexual, dioecious; internal fertilization in many
Habitat	Marine, freshwater, terrestrial; flying forms common (insects)

 

Major Classes

Class	Characteristics	Examples
Crustacea	Mostly aquatic, 2 pairs antennae, biramous appendages	Crab, Lobster, Prawn, Cyclops
Chelicerata (Arachnida)	No antennae, 4 pairs legs, body divided into cephalothorax and abdomen	Spider, Scorpion, Mite, Tick
Myriapoda	Body elongated with many segments, each segment with 1–2 pairs legs	Centipede, Millipede
Insecta	Body divided into head, thorax, abdomen; 3 pairs legs, usually 2 pairs wings	Grasshopper, Butterfly, Cockroach

 

Special Features

Feature	Description
Exoskeleton	Provides protection, prevents desiccation; molted periodically
Jointed Appendages	Specialized for walking, swimming, feeding, defense
Metamerism	Body segments fused into tagmata (head, thorax, abdomen)
Respiration	Gills in aquatic forms; tracheae in terrestrial insects; book lungs in spiders
Circulatory System	Open, hemolymph circulates nutrients and hormones

 

Fun / Quick Facts

Facts About Arthropoda
1.	Largest phylum in the animal kingdom in terms of species number.
2.	Exoskeleton is made of chitin and provides mechanical support.
3.	Tagmatization allows specialization of body segments.
4.	Most insects can fly, making them highly adaptive and widespread.
5.	Arthropods play crucial roles in ecology as pollinators, decomposers, and predators.

 

Phylum Mollusca – मोलस्का (Soft-bodied Animals)

Phylum Mollusca में soft-bodied, bilaterally symmetrical, triploblastic और coelomate animals आते हैं। अधिकांश aquatic होते हैं, लेकिन कुछ terrestrial भी पाए जाते हैं। शरीर non-segmented होता है और कई में hard calcareous shell होती है।

विशेषताएँ (Characteristics)

Characteristics of Mollusca
Organisation	Organ system level; Triploblastic
Symmetry	Bilateral symmetry
Body Cavity	Coelomate
Segmentation	Absent externally; some internal organ repetition
Digestive System	Complete, mouth and anus present; radula present in most (except bivalves)
Circulatory System	Open type (except cephalopods which have closed system)
Excretory System	Paired nephridia
Nervous System	Cerebral ganglia with paired nerve cords; more developed in cephalopods
Reproduction	Mostly sexual, dioecious; external fertilization in some, internal in cephalopods
Habitat	Marine, freshwater, and terrestrial

 

Body Structure

Feature	Description
Body Parts	Head-foot (locomotion and feeding), visceral mass (organs), mantle (secretes shell)
Shell	External calcareous shell in many (e.g., snail, clam)
Radula	Chitinous toothed structure for scraping food (absent in bivalves)

 

Major Classes

Class	Characteristics	Examples
Polyplacophora	Marine, dorsal shell with 8 plates, ventral foot for locomotion	Chiton
Gastropoda	Univalve shell, coiled in most, head well developed, radula present	Snail, Slug, Limax
Bivalvia	Two valves, no radula, filter feeders, mostly aquatic	Clam, Oyster, Pinctada
Cephalopoda	Head-foot modified into tentacles, closed circulatory system, intelligent, predatory	Octopus, Squid, Nautilus

 

Fun / Quick Facts

Facts About Mollusca
1.	Second largest phylum after Arthropoda.
2.	Radula is a unique feeding organ of mollusks.
3.	Cephalopods are the most intelligent invertebrates.
4.	Bivalves are important for pearls and food.
5.	Mollusks exhibit great diversity in habitat, form, and behavior.

 

Phylum Echinodermata – इकाइनोडर्मा (Spiny-skinned Animals)

Phylum Echinodermata में exclusively marine, bilaterally symmetrical larvae और radially symmetrical adults वाले coelomate, triploblastic animals आते हैं। शरीर spiny और calcareous endoskeleton से ढका होता है।

विशेषताएँ (Characteristics)

Characteristics of Echinodermata
Organisation	Organ system level; Triploblastic
Symmetry	Larvae bilateral, adults pentamerous radial symmetry
Body Cavity	Coelomate (true coelom)
Body Segmentation	No true segmentation
Skeleton	Endoskeleton of calcareous ossicles with spines
Digestive System	Complete in most; mouth on oral side, anus on aboral side
Circulatory System	Water vascular system; circulates coelomic fluid, aids in locomotion
Excretory System	Diffusion through coelomic fluid; no specialized excretory organs
Nervous System	No brain; nerve ring around mouth, radial nerve cords
Reproduction	Mostly sexual, dioecious; external fertilization, some regeneration
Habitat	Exclusively marine

 

Major Classes

Class	Characteristics	Examples
Asteroidea	Star-shaped, pentamerous symmetry, tube feet present	Starfish (Asterias)
Ophiuroidea	Slender, branched arms, central disc distinct, tube feet without suckers	Brittle star (Ophiura)
Echinoidea	Globular or disc-shaped, no arms, spines movable	Sea urchin (Echinus), Sand dollar
Holothuroidea	Cucumber-shaped, elongated body, reduced skeleton, tube feet	Sea cucumber (Holothuria)
Crinoidea	Feather-like arms, sessile or stalked, mouth on upper surface	Sea lilies, Feather stars

 

Special Features

Feature	Description
Water Vascular System	Used for locomotion, feeding, and respiration; includes tube feet
Endoskeleton	Calcareous ossicles embedded in dermis, provides support and protection
Regeneration	Can regenerate lost arms; some species can regenerate entire body from a part
Radial Symmetry in Adults	Allows adaptation to sessile or slow-moving life

 

Fun / Quick Facts

Facts About Echinodermata
1.	Exclusively marine invertebrates.
2.	Water vascular system is unique to echinoderms.
3.	Adults show pentamerous radial symmetry, larvae are bilateral.
4.	Capable of remarkable regeneration.
5.	Endoskeleton provides protection and support without limiting growth.

 

Phylum Hemichordata – हेमिकॉर्डाटा

Phylum Hemichordata में bilaterally symmetrical, triploblastic, coelomate marine invertebrates आते हैं। ये chordates की तरह कुछ विशेष लक्षण जैसे dorsal nerve cord और pharyngeal gill slits दिखाते हैं।

विशेषताएँ (Characteristics)

Characteristics of Hemichordata
Organisation	Organ system level; Triploblastic
Symmetry	Bilateral symmetry
Body Cavity	Coelomate
Body Segmentation	No true segmentation
Skeleton	Absent; body soft and worm-like
Digestive System	Complete, mouth and anus present; pharyngeal gill slits present
Circulatory System	Closed type; heart absent, blood flows through dorsal and ventral vessels
Excretory System	Absent or by diffusion
Nervous System	Dorsal tubular nerve cord, some ventral nerve fibers
Reproduction	Mostly sexual, dioecious; external fertilization
Habitat	Marine, burrowing in sand or mud

 

Body Structure

Body Region	Characteristics
Proboscis	Anterior, used for burrowing and feeding
Collar	Middle region; bears mouth and sometimes nerve cord
Trunk	Posterior elongated region; contains digestive and reproductive organs

 

Major Classes

Class	Characteristics	Examples
Enteropneusta	Worm-like, burrowing, proboscis well developed	Saccoglossus, Balanoglossus
Pterobranchia	Colonial, tube-dwelling, small, sessile	Rhabdopleura, Cephalodiscus

 

Special Features

Feature	Description
Pharyngeal Gill Slits	Present; similar to chordates, used for filter feeding
Dorsal Nerve Cord	Partially tubular, a chordate-like feature
Coelom	Tripartite: protocoel, mesocoel, metacoel
Habitat	Marine, burrowing in sand or mud

 

Fun / Quick Facts

Facts About Hemichordata
1.	Bridge between invertebrates and chordates due to pharyngeal gill slits and dorsal nerve cord.
2.	Mostly marine, sedentary or burrowing worms.
3.	Coelom divided into three distinct cavities: protocoel, mesocoel, metacoel.
4.	Reproduction is sexual with external fertilization.
5.	Provide insights into evolution of chordates.

 

Phylum Chordata – कर्डाटा (Chordates)

Phylum Chordata में bilaterally symmetrical, triploblastic, coelomate animals आते हैं जिनमें कुछ विशेष chordate features पाई जाती हैं। ये features embryonic या adult stage में मौजूद हो सकती हैं।

विशेषताएँ (Characteristics)

Characteristics of Chordata
Organisation	Organ system level; Triploblastic
Symmetry	Bilateral symmetry
Body Cavity	Coelomate (true coelom)
Segmentation	Metamerism present in muscles and vertebrae
Digestive System	Complete, mouth and anus present; specialized organs
Circulatory System	Closed type with heart; blood vessels with arteries, veins, capillaries
Excretory System	Paired nephrons or kidneys
Nervous System	Dorsal tubular nerve cord; brain present in most; paired sense organs
Reproduction	Mostly sexual; dioecious; external or internal fertilization
Habitat	Marine, freshwater, and terrestrial

 

Chordate Features

Feature	Description
Notochord	Flexible rod-like structure along dorsal side; replaced by vertebral column in vertebrates
Dorsal Tubular Nerve Cord	Forms spinal cord and brain in vertebrates
Pharyngeal Gill Slits	Present in pharynx; used for filter feeding in invertebrate chordates or respiration in vertebrates
Post-anal Tail	Extension of body beyond anus; aids in locomotion in aquatic forms
Endoskeleton	Cartilaginous or bony; provides support and protection

 

Major Subphyla

Subphylum	Characteristics	Examples
Urochordata	Marine, sessile as adult, notochord in larva only	Tunicates, Sea squirts
Cephalochordata	Marine, fish-like, notochord persists in adult, segmented muscles	Lancelets (Branchiostoma)
Vertebrata (Craniata)	Notochord replaced by vertebral column, well-developed brain and sense organs	Fishes, Amphibians, Reptiles, Birds, Mammals

 

Fun / Quick Facts

Facts About Chordata
1.	Phylum Chordata is divided into three subphyla: Urochordata, Cephalochordata, Vertebrata.
2.	Notochord is a defining feature, present at least in embryonic stage.
3.	Dorsal nerve cord develops into spinal cord and brain in vertebrates.
4.	Post-anal tail is retained in aquatic vertebrates, reduced in humans.
5.	Vertebrates have a well-developed endoskeleton that supports large body size and movement.

 

Difference between Chordata and Non-Chordata (कॉर्डेटा और नॉन-कॉर्डेटा में अंतर)

Animal Kingdom is broadly divided into Chordata and Non-Chordata.
Chordates have a notochord, while non-chordates do not. Below is a comparison:

Fact: लगभग 90-95% जानवर Non-Chordata में आते हैं। Chordata की संख्या अपेक्षाकृत कम है।

 

Feature (विशेषता)	Chordata (कॉर्डेटा)	Non-Chordata (नॉन-कॉर्डेटा)
Notochord	Present in embryonic stage (नोटोकोर्ड पाया जाता है)	Absent (नोटोकोर्ड नहीं पाया जाता)
Nerve Cord	Dorsal, hollow nerve cord (पृष्ठीय खोखला)	Ventral, solid nerve cord (निचला और ठोस)
Pharyngeal gill slits	Present at some stage (कभी न कभी मौजूद)	Absent
Heart	Ventral side (ह्रदय पृष्ठीय भाग में)	Dorsal side (ह्रदय ऊपरी भाग में)
Coelom	True coelomate (सच्चा कोएलम)	Acoelomate / Pseudocoelomate / Coelomate (विभिन्न प्रकार)
Example	Fishes, Amphibians, Reptiles, Birds, Mammals	Porifera, Cnidaria, Annelida, Arthropoda, Mollusca, etc.

 

Key Point: नोटोकोर्ड की उपस्थिति ही Chordata और Non-Chordata के बीच सबसे बड़ा अंतर है।

 

Class Cyclostomata (कक्षा सायक्लोस्टोमा)

Cyclostomata are jawless, eel-like aquatic vertebrates. They are the most primitive living chordates under superclass Agnatha. इनका शरीर लंबा और बेलनाकार होता है तथा मुँह गोलाकार चूषण कप जैसा होता है।

Fact: Cyclostomes को “Living Fossils” भी कहा जाता है क्योंकि ये सबसे प्राचीन जबड़ा-रहित कशेरुकी हैं।

 

General Characteristics (सामान्य लक्षण)

• Body elongated, cylindrical and eel-like (लंबा और बेलनाकार शरीर)।
• No jaws, mouth is circular and sucking type (जबड़े नहीं, मुँह गोलाकार और चूषण कप जैसा)।
• Endoskeleton is cartilaginous (आंतरिक कंकाल उपास्थीय)।
• No paired fins, only median fins are present (युग्मित पंख अनुपस्थित)।
• Respiration through 6–15 pairs of gill pouches (श्वसन 6–15 युग्म गिल थैली से)।
• Closed circulatory system with two-chambered heart (बंद रक्त परिसंचरण और द्विकक्षीय ह्रदय)।
• They are ectoparasitic on fishes (ये परजीवी रूप से मछलियों के शरीर से चिपककर खून चूसते हैं)।
• Fertilization is external (निषेचन बाहरी)।
• Development is indirect with larval stage (विकास अप्रत्यक्ष, लार्वा सहित)।

Classification Table (वर्गीकरण सारणी)

Feature (विशेषता)	Cyclostomata
Body Shape	Elongated, cylindrical (eel-like)
Jaws	Absent (Jawless)
Skeleton	Cartilaginous (उपास्थीय)
Fins	Unpaired (median only)
Respiration	Through gill pouches
Heart	Two-chambered
Habitat	Marine (but migrate to freshwater for spawning)
Examples	Petromyzon (Lamprey), Myxine (Hagfish)

 

Key Point: सभी Cyclostomes Marine होते हैं लेकिन प्रजनन (spawning) के लिए Freshwater में प्रवास करते हैं।

 

Class Chondrichthyes (कक्षा कॉन्ड्रिकथीज़)

Chondrichthyes are cartilaginous fishes. इनका आंतरिक कंकाल पूरी तरह उपास्थि (cartilage)</b से बना होता है। ये समुद्री जलचर होते हैं और अधिकतर शिकारी (predatory) प्रवृत्ति के होते हैं।

Fact: Sharks, skates और rays इस वर्ग के प्रमुख सदस्य हैं। इनमें तैरने के लिए swim bladder अनुपस्थित होता है।

 

General Characteristics (सामान्य लक्षण)

• Skeleton made of cartilage (कंकाल उपास्थीय)।
• Body is streamlined and laterally compressed (शरीर सुडौल व पार्श्व से दबा हुआ)।
• Jaws are well developed (जबड़े विकसित)।
• Mouth is ventral in position (मुख निचले भाग में स्थित)।
• Skin tough, covered with placoid scales (त्वचा मोटी और प्लाकोइड स्केल्स से ढकी)।
• Teeth are modified placoid scales (दांत प्लाकोइड स्केल्स से बने)।
• Caudal fin is heterocercal (पूंछ का पंख विषमपक्षीय)।
• Gills are 5–7 pairs, uncovered by operculum (गिल आवरण रहित)।
• Heart is two-chambered (auricle + ventricle)।
• Cold-blooded (शीत-रुधिरजीवी)।
• Swim bladder absent (swimming के लिए निरंतर सक्रिय रहना पड़ता है)।
• Fertilization internal (निषेचन आंतरिक)।
• Many are viviparous (अधिकतर शिशुजन्‍मी)।

Classification Table (वर्गीकरण सारणी)

Feature (विशेषता)	Chondrichthyes
Skeleton	Cartilaginous (उपास्थीय)
Scales	Placoid scales
Mouth	Ventral
Caudal Fin	Heterocercal
Respiration	By 5–7 pairs of gills (without operculum)
Heart	Two-chambered
Reproduction	Internal fertilization, many viviparous
Examples	Shark, Dogfish (Scoliodon), Sting ray, Torpedo (Electric ray)

 

Key Point: Sharks के शरीर में liver oil (squalene) होता है जो buoyancy (तैरने की क्षमता) बनाए रखने में मदद करता है।

 

Class Osteichthyes (कक्षा ऑस्टिकथीज़)

Osteichthyes are commonly called bony fishes. इनका आंतरिक कंकाल पूरी तरह हड्डियों (bone)</b से बना होता है। ये सबसे बड़ा वर्ग है जिसमें लगभग 30,000 से अधिक प्रजातियाँ शामिल हैं।

Fact: Bony fishes ही वह वर्ग है जो मानव भोजन के लिए सबसे अधिक उपयोगी है।

 

General Characteristics (सामान्य लक्षण)

• Skeleton is made of bones (कंकाल हड्डी का)।
• Body is streamlined and spindle-shaped (शरीर सुडौल और धुरी आकार का)।
• Skin covered with cycloid or ctenoid scales (त्वचा स्केल्स से ढकी)।
• Mouth is usually terminal (मुख अग्र भाग में)।
• Gills are covered by a bony operculum (गिल्स पर हड्डी का ढक्कन होता है)।
• Caudal fin is homocercal (पूंछ का पंख समपक्षीय)।
• Air bladder present, helps in buoyancy (एयर ब्लैडर तैरने में सहायक)।
• Heart two-chambered (auricle + ventricle)।
• Cold-blooded (शीत-रुधिरजीवी)।
• Fertilization external (निषेचन बाहरी)।
• Most are oviparous with direct development (अधिकतर अंडज और प्रत्यक्ष विकास)।

Classification Table (वर्गीकरण सारणी)

Feature (विशेषता)	Osteichthyes
Skeleton	Bony (हड्डीयुक्त)
Scales	Cycloid या Ctenoid
Mouth	Terminal
Caudal Fin	Homocercal
Respiration	By gills covered with operculum
Heart	Two-chambered
Reproduction	External fertilization, mostly oviparous
Examples	Labeo (Rohu), Catla, Clarias (Magur), Hippocampus (Sea horse), Exocoetus (Flying fish)

 

Key Point: Osteichthyes की सबसे प्रसिद्ध मछली है Hippocampus (Sea horse), जिसमें शरीर का आकार घोड़े जैसा होता है।

 

Class Amphibia (कक्षा उभयचर)

Amphibians are the first vertebrates that can live both on land and in water. इन्हें उभयचर कहा जाता है क्योंकि ये दो प्रकार के वातावरण – जलीय और स्थलीय – दोनों में रह सकते हैं।

Fact: Amphibians are considered as first land vertebrates because they evolved adaptations to live on land as well as water.

 

General Characteristics (सामान्य लक्षण)

• Body is divisible into head and trunk (शरीर सिर और धड़ में विभाजित)।
• Skin is moist, glandular, and without scales (त्वचा नम, ग्रंथियुक्त और बिना स्केल्स के)।
• They have two pairs of limbs; digits without claws (दो जोड़े पैर, उंगलियों पर नाखून नहीं)।
• Respiration occurs through gills, lungs, skin, and buccopharyngeal cavity (श्वसन गलफड़ों, फेफड़ों, त्वचा और मुखगुहा द्वारा)।
• Heart is three-chambered (2 auricles + 1 ventricle)।
• Cold-blooded (शीत-रुधिरजीवी)।
• External fertilization (निषेचन बाहरी)।
• Development indirect with larval stage (अप्रत्यक्ष विकास, लार्वा सहित – टेडपोल)।
• They are oviparous (अंडज)।

Classification Table (वर्गीकरण सारणी)

Feature (विशेषता)	Amphibia
Habitat	Both land and water
Skin	Moist, glandular, scaleless
Limbs	Two pairs, digits without claws
Respiration	By gills (larva), lungs, skin
Heart	Three-chambered
Fertilization	External
Reproduction	Oviparous
Examples	Frog (Rana), Toad (Bufo), Salamander, Ichthyophis (Caecilian)

 

Key Point: Amphibians का larval stage (जैसे टेडपोल) जलीय और वयस्क अवस्था स्थलीय होती है – यह amphibians की विशेषता है।

 

Class Reptilia (कक्षा सरीसृप)

Reptiles are cold-blooded vertebrates that are adapted to live on land.
इनका शरीर शुष्क और कड़ा होता है, और ये जल पर निर्भर नहीं रहते। Reptiles की त्वचा scaly होती है और ये अंडज (oviparous) होते हैं।

Fact: Reptiles were the first vertebrates to be fully adapted to life on land without depending on water for reproduction.

 

General Characteristics (सामान्य लक्षण)

• Body covered with dry, keratinized scales (त्वचा सूखी और कठोर, केरेटिनयुक्त)।
• Body divisible into head, neck, trunk and tail (सिर, गर्दन, धड़ और पूंछ)।
• Limbs well developed, usually pentadactyl (पैर व हाथ विकसित, 5 उंगलियाँ)।
• Respiration by lungs (श्वसन फेफड़ों द्वारा)।
• Heart mostly three-chambered (2 auricles + 1 ventricle), crocodiles have four-chambered heart (4 कक्ष)।
• Cold-blooded (शीत-रुधिरजीवी)।
• Fertilization internal (निषेचन आंतरिक)।
• Reproduction mostly oviparous with leathery eggs (अंडज, त्वचा जैसी खोल वाली अंडियाँ)।
• Metanephric kidneys (उच्च विकसित वृक्क)।

Classification Table (वर्गीकरण सारणी)

Feature (विशेषता)	Reptilia
Habitat	Land (mostly), some aquatic
Skin	Dry, scaly
Limbs	Two pairs, pentadactyl
Respiration	Lungs
Heart	3-chambered (except crocodiles – 4-chambered)
Fertilization	Internal
Reproduction	Oviparous with leathery eggs
Examples	Crocodile, Lizard, Snake, Turtle, Chameleon

 

Key Point: Reptiles are the first vertebrates fully adapted to terrestrial life with internal fertilization and shelled eggs.

 

Class Aves (कक्षा पक्षी)

Aves are warm-blooded vertebrates adapted for flight.
इनकी त्वचा पर पंख (feathers) होते हैं और शरीर हल्का और शक्तिशाली उड़ान के लिए अनुकूल होता है।

Fact: Birds are the only vertebrates with feathers, which help in flight, insulation, and courtship displays.

 

General Characteristics (सामान्य लक्षण)

• Body covered with feathers, skin with scales on legs (पंख और त्वचा पर स्केल)।
• Forelimbs modified as wings (अग्र पैरों का रूप पंख के रूप में)।
• Hollow bones reduce weight (हड्डियाँ खोखली और हल्की)।
• Beak without teeth (दांत नहीं, चोंच)।
• Respiration by lungs with air sacs (फेफड़े और वायु थैले)।
• Heart is four-chambered (चार-कक्षीय)।
• Warm-blooded (गर्म-रुधिरजीवी)।
• Fertilization internal (निषेचन आंतरिक)।
• Oviparous, eggs with hard calcareous shell (अंडज, कठोर खोल वाली अंडियाँ)।

Classification Table (वर्गीकरण सारणी)

Feature (विशेषता)	Aves
Body covering	Feathers, scales on legs
Forelimbs	Modified as wings
Skeleton	Light, hollow bones
Mouth	Beak without teeth
Heart	Four-chambered
Respiration	Lungs with air sacs
Fertilization	Internal
Reproduction	Oviparous, hard-shelled eggs
Examples	Parrot, Crow, Pigeon, Eagle, Owl, Peacock

 

Key Point: Birds are warm-blooded vertebrates uniquely adapted for flight with feathers and hollow bones.

 

Class Mammalia (कक्षा स्तनधारी)

Mammals are warm-blooded vertebrates that feed their young with milk produced by mammary glands.
ये जटिल और विकसित शारीरिक संरचना वाले जानवर होते हैं और शरीर पर बाल (hair) पाए जाते हैं।

Fact: Mammals are the most advanced vertebrates, with complex nervous system and parental care.

 

General Characteristics (सामान्य लक्षण)

• Body covered with hair or fur (बाल या फर से ढका हुआ)।
• Mammary glands present for milk secretion (स्तन ग्रंथियाँ दूध निकालने के लिए)।
• Heart four-chambered (चार-कक्षीय)।
• Warm-blooded (गर्म-रुधिरजीवी)।
• Lungs for respiration with diaphragm (फेफड़े और डायाफ्राम के साथ)।
• Internal fertilization (निषेचन आंतरिक)।
• Mostly viviparous, some oviparous like Monotremes (अधिकतर जीवजन्मी, कुछ अंडज)।
• Well-developed brain and sensory organs (विकसित मस्तिष्क और इंद्रियाँ)।

Classification Table (वर्गीकरण सारणी)

Feature (विशेषता)	Mammalia
Body covering	Hair or fur
Reproductive glands	Mammary glands present
Heart	Four-chambered
Respiration	Lungs with diaphragm
Fertilization	Internal
Reproduction	Mostly viviparous, Monotremes oviparous
Brain	Highly developed
Examples	Human, Lion, Tiger, Elephant, Bat, Whale, Kangaroo

 

Key Point: Mammals are warm-blooded, have hair, produce milk, and show parental care, making them the most advanced vertebrates.

 

External Links for Animal Kingdom (बाहरी लिंक)

यहाँ कुछ महत्वपूर्ण बाहरी स्रोत दिए गए हैं जहाँ से विद्यार्थी Animal Kingdom के बारे में और गहराई से अध्ययन कर सकते हैं:

• NCERT Official Textbooks – कक्षा 11 Biology की आधिकारिक NCERT किताब।
• Byju’s – Animal Kingdom (NEET Notes) – NEET तैयारी के लिए सरल नोट्स।
•  Toppr – Animal Kingdom Guide – विस्तृत गाइड और प्रश्न अभ्यास।
• Embibe – Animal Kingdom – MCQs, क्विज़ और प्रैक्टिस।
•  Khan Academy – Animal Diversity – अंग्रेज़ी में सरल व्याख्या।
•  Wikipedia – Animal – जानवरों का सामान्य विश्वकोशीय लेख।

Read more:- Class 10th NCERT Science notes in hindi