Study Material and Notes of Ch 4 Animal Kingdom Class 11th Biology
Topics in the Chapter
Basis of Classification
→ Animals are classified on the basis of following few fundamental features:
(i) Levels of Organisation:
(a) Cellular level : Cells are arranged as loose cell aggregates.
Example: sponges.
(b) Tissue level : The cells performing the same function are arranged into tissues.
Example: Coelenterates.
(c) Organ level : Tissues are grouped together to form organs, each specialised for a particular function.
Example: platyhelminthes.
(d) Organ system level : Organs are associated to form functional systems like Annelids, Arthropods, Molluscs, Echinoderms and Chordates.
→ Example: Circulatory System.
• Open type: Blood pumped out through heart. Not confined to blood vessels. Cells and tissues aredirectly bathed in it.
• Closed types: Blood is circulated through blood vessels (arteries,veins and capillaries)
(ii) Symmetry
• Asymmetrical: Cannot be divided into equal halves through median plane.
Example: Sponges.
• Radial symmetry: Any plane passing through central axis can divide organism into identical halves. Example: coelentrates,Ctenophores and echinoderms.
• Bilateral symmetry: Only one plane can divide the organism into two identical left and right halves
Example: Annelids and Arthropods.
(iii) Germinal Layers
• Diploblastic : Cells arranged in two embryonic layers i.e., external ectoderm and internal endoderm. (Mesoglea may be present in between ectoderm and endoderm)
Example: porifers and Coelentrates. (Cnidarians)
• Triploblastic: Three layers present in developing embryo i.e., ectoderm, mesoderm and endoderm.
Example: Platyhelminthes to Chordates.
(iv) Coelom (Body cavity which is lined by mesoderm)
• Coelomates: Have coelom
Example: Annelids, Arthropods, molluscs, Echinoderms, Chordates etc.
• Pseudocoelomates: No true coelem as mesoderm is present in scattered pouches between ectoderm and endoderm.
Example: Aschelminthes.
Acoelomates : Body cavity is absent
Example: Platyhelminthes.
(v) Segmentation
(A) True Metamerism
→ Found in Annelida,Arthropoda, Chordata.
→ Segmentation is external as well as a internal in Annelids.
→ Segmentation is external in Arthropods.
→ Segmentation is internal in chordates.
• Metamerism: If body is externally and internally divided into segments (metameres) with serial repetition of atleast some organs, then phenomenon is called metamerism.
Example: Earthworm.
(B) Pseudometamerism
→ Found in tapeworm.
→ The proglottids (segments of tapeworm) budded off from neck not emryonic in origin.
(vi) Notochord
→ Rod-like structure formed during embryonic development on the dorsal side.
→ It is mesodermally derived.
Example: Chordates.
→ Non-chordates do not have notochord. Example: porifera to echinoderms.
Phylum Porifera
→ Also called sponges.
→ Are usually marine and asymmetrical.
→ Have cellular level of organisation and diploblastic animals.
→ Food gathering, respiratory exchange and removal of wastes occurs through water canal system. Digestion intracellular.
→ Ostia (minute pores on body), spongocoel (body cavity) and osculum help in water transport.
→ They are lined by choanocytes (collar cells).
→ Body wall has skeleton of spicules or spongin fibres.
→ Animals are hermaphrodite. Fertilisation internal. Development is indirect (i.e., has a larval stage distinct from adult stage)
Example: Sycon, Euspongia.
→ Spongilla (Fresh water sponge)
Phylum Coelenterata
→ Also called Cnidarians.
→ Are usually marine and radially symmetrical.
→ Sessile or free swimming.
→ Have tissue level of organisation.
→ Are diploblastic (with mesogloea)
→ Capture of prey, anchorage and defence occurs through cnidoblasts/cnidocytes (have stinging capsules nematocytes) present on tentacles.
→ Digestion extracellular and intracellular.
→ Have a contral gastro-vascular cavity and an opening, hypostome.
→ Body wall of some composed of calcium carbonate. Example: corals.
→ Exhibit two body forms : polyp and medusa Example: Hydra, Aurelia.
→ Alternation of generation between body forms called metagenesis ocurs in Obelia where :
(b) Super Class: Tetrapoda
NCERT Solutions of Class 11 Animal Kingdom
- Basis of Classification
- Phylum Porifera
- Phylum Coelenterata
- Phylum Ctenophora
- Phylum Plathyhelminthes
- Phylum Aschelminthes
- Phylum Annelida
- Phylum Arthropoda
- Phulum Mollusca
- Phylum Echinodermata
- Phyum Hemichordata
- Phylum Chordata
- Division of Vertebrata
- Super-class: Pisces
- Super Class: Tetrapoda
Basis of Classification
→ Animals are classified on the basis of following few fundamental features:
(i) Levels of Organisation:
(a) Cellular level : Cells are arranged as loose cell aggregates.
Example: sponges.
(b) Tissue level : The cells performing the same function are arranged into tissues.
Example: Coelenterates.
(c) Organ level : Tissues are grouped together to form organs, each specialised for a particular function.
Example: platyhelminthes.
(d) Organ system level : Organs are associated to form functional systems like Annelids, Arthropods, Molluscs, Echinoderms and Chordates.
→ Example: Circulatory System.
• Open type: Blood pumped out through heart. Not confined to blood vessels. Cells and tissues aredirectly bathed in it.
• Closed types: Blood is circulated through blood vessels (arteries,veins and capillaries)
(ii) Symmetry
• Asymmetrical: Cannot be divided into equal halves through median plane.
Example: Sponges.
• Radial symmetry: Any plane passing through central axis can divide organism into identical halves. Example: coelentrates,Ctenophores and echinoderms.
• Bilateral symmetry: Only one plane can divide the organism into two identical left and right halves
Example: Annelids and Arthropods.
(iii) Germinal Layers
• Diploblastic : Cells arranged in two embryonic layers i.e., external ectoderm and internal endoderm. (Mesoglea may be present in between ectoderm and endoderm)
Example: porifers and Coelentrates. (Cnidarians)
• Triploblastic: Three layers present in developing embryo i.e., ectoderm, mesoderm and endoderm.
Example: Platyhelminthes to Chordates.
(iv) Coelom (Body cavity which is lined by mesoderm)
• Coelomates: Have coelom
Example: Annelids, Arthropods, molluscs, Echinoderms, Chordates etc.
• Pseudocoelomates: No true coelem as mesoderm is present in scattered pouches between ectoderm and endoderm.
Example: Aschelminthes.
Acoelomates : Body cavity is absent
Example: Platyhelminthes.
(v) Segmentation
(A) True Metamerism
→ Found in Annelida,Arthropoda, Chordata.
→ Segmentation is external as well as a internal in Annelids.
→ Segmentation is external in Arthropods.
→ Segmentation is internal in chordates.
• Metamerism: If body is externally and internally divided into segments (metameres) with serial repetition of atleast some organs, then phenomenon is called metamerism.
Example: Earthworm.
(B) Pseudometamerism
→ Found in tapeworm.
→ The proglottids (segments of tapeworm) budded off from neck not emryonic in origin.
(vi) Notochord
→ Rod-like structure formed during embryonic development on the dorsal side.
→ It is mesodermally derived.
Example: Chordates.
→ Non-chordates do not have notochord. Example: porifera to echinoderms.
Phylum Porifera
→ Also called sponges.
→ Are usually marine and asymmetrical.
→ Have cellular level of organisation and diploblastic animals.
→ Food gathering, respiratory exchange and removal of wastes occurs through water canal system. Digestion intracellular.
→ Ostia (minute pores on body), spongocoel (body cavity) and osculum help in water transport.
→ They are lined by choanocytes (collar cells).
→ Body wall has skeleton of spicules or spongin fibres.
→ Animals are hermaphrodite. Fertilisation internal. Development is indirect (i.e., has a larval stage distinct from adult stage)
Example: Sycon, Euspongia.
→ Spongilla (Fresh water sponge)
Phylum Coelenterata
→ Also called Cnidarians.
→ Are usually marine and radially symmetrical.
→ Sessile or free swimming.
→ Have tissue level of organisation.
→ Are diploblastic (with mesogloea)
→ Capture of prey, anchorage and defence occurs through cnidoblasts/cnidocytes (have stinging capsules nematocytes) present on tentacles.
→ Digestion extracellular and intracellular.
→ Have a contral gastro-vascular cavity and an opening, hypostome.
→ Body wall of some composed of calcium carbonate. Example: corals.
→ Exhibit two body forms : polyp and medusa Example: Hydra, Aurelia.
→ Alternation of generation between body forms called metagenesis ocurs in Obelia where :
→ Example: Physalia, Adamsia, Pennatula, Gorgonia,Meandrina.
Phylum Ctenophora
→ Also called as sea walnuts or comb jellies.
→ Are exclusively marine, radially symmetrical.
→ Have tissue level organisation, are diploblastic.
→ Digestion both extra and intracellular.
→ Body has eight external rows of ciliated comb plates for locomotion.
→ Show Bioluminescence (Property of living organisms to emit light).
→ Hermaphrodite (sexes are not separate).
→ Only sexual reproduction occurs. Exernal fertilization. Indirect development.
Example: Ctenoplana, Pleurobrachia.
Phylum Plathyhelminthes
→ Also called as ‘flat worms’.
→ Have dorsoventrally flattened body. Are mostly endoparasites in animals.
→ Are bilaterally symmetrical, triploblastic, acoelomate,with organ level of orgnisation.
→ Absorb nutrients through body surface.
→ Parasitic forms have hooks and suckers.
→ ‘Flame cells’ help in osmoregulation and excretion.
→ Sexes not separate.
→ Fertilisation internal. Many larval stages present. Planaria has high regeneration capacity.
Example: Taenia, Fasciola.
Phylum Aschelminthes
→ Also called ‘round worms’.
→ May be free living, parasitic, aquatic or terrestrial.
→ Are bilaterally symmetrical, triploblastic, pseudocoelomate.
→ Alimentary canal complete (has muscular pharynx), wastes removed through excretory pore.
→ Sexes separate. (dioecious)
→ Females longer than males.
→ Fertilisation internal. Development direct or indirect. Example: Ascaris,Wuchereria, Ancylostoma.
Phylum Annelida
→ Are aquatic or terrestrial, free-living or parasitic.
→ Are bilaterally symmetrical, triploblastic, organ-system level of organisation and metamerically segmented body.
→ Are coelomate animals.
→ Have longitudinal and circular muscles for locomation.
→ Have closed circulatory system.
→ Nereis (dioecious and aquatic annelid) has lateral appendages called parapodia for swimming.
→Have nephridia for osmoregulation and excretion.
→ Neural system consists of paired gangila connected by lateral nerves to a double ventral nerve cord.
→ Reproduction is sexual.
→ Example: Earthworm (Pheretima) and Leech (Hirudinaria) which are hermaph
rodites (i.e., monoecious).
Phylum Arthropoda
→ Largest phylum of Animalia.
→ Are bilaterally symmetrical, triplobastic, segmented externally and organ system level of organisation, coelomate.
→ Body divisible into head, thorax, abdomen and has a chitinous exoskeleton. Jointed appendages are present.
→ Respiration by gills, book gills, book lungs or tracheal system. Excretion through malpighian tubules.
→ Sensory organs: Antennae, eyes; Organs of balance : Statocysts.
→ Fertilisation usaully internal. Development is indirect or direct. Are mostly oviparous.
→ Example: Apis, Bombyx, Laccifer, Anopheles, Culex, Aedes, Locusta, Limulus.
Phulum Mollusca
→ Second largest phylum of Animalia.
→ Terrestrial or aquatic
→ Are bilaterally symmetrical, triplobastic and organ system level of organisation, coelomate.
→ Body vidisble into head, muscular foot and visceral hump and is covered by calcareous shell and is unsegmented.
→ Mantle: Soft and spongy layer of skin.
Mantle cavity: Space between visceral hump and mantle.
→ Respiration and excretion by feather like gills in mantle cavity.
→ Head has sensory tentacles. Radula-file like rasping organ for feeding in mouth.
→ Are oviparous, dioecious, have indirect development.
→ Example: Plia, Pinctada, Octopus,Sepia, Loligo, Aplysia, Dentalium, Chaetopleura.
Phylum Echinodermata
→ Are spiny bodied organisms with endoskeleton of calcareous ossicles.
→ Are exclusively marine, radially symmetrical in adult but bilaterally symmetrical in larval stage. Organ system level of organisation.
→ Triploblastic and coelomate.
→ Digestive system complete. Mouth ventral, Anus on dorsal side.
→ Food gathering, respiration, locomotion carried out by water vascular system.
→ Excretory system is absent.
→ Reproduction–sexual, sexes are separate.
→ Fertilisation external. Development indirect (free swimming larva)
→ Example: Asterias, Cucumaria, Antedon, Echinus, ophiura.
Phyum Hemichordata
→ Represents small group of worm-like organisms.
→ Was earlier placed as sub-phylum of Phyum Chordata.
→ Bilaterally symmetrical, triploblastic and coelomate with organ system level of organisation.
→ Body cylindrical, has proboscis, collar and trunk.
→ Circulatory System–open.
→ Respiration by gills, excretion by proboscis gland.
→ Sexes separate, external fertiliastion, indrect development.
→ Example: Balanoglossus, saccoglossus.
Phylum Chordata
→ Presence of Notochord.
→ Have dorsal hollow nerve chord.
→ Have paired pharyngeal gill slits.
→ Bilaterally symmetrical, triploblastic, coelomate, organ system level of organisation.
→ Heart is ventral.
→ Post anal tail present, closed circulatory system.
(i) Sub-Phyla Urochordata /Tunicata
→ Notocohord present only in larval tail.
Example: Ascidia, Salpa, Doliolum
(ii) Sub-phyla Cephalochordata
→ Notochord extends from head to tail (Persistent)
Example: Amphioxus.
(iii) Sub-Phyla Vertebrata
→ Have notochord only during embryonic period.
→ Notochord gets replaced by bony or cartilaginous vertebral column.
→ Have ventral muscular heart, kidneys for excretion and osmoregulation, paired appendages (fins or limbs)
Vertebrata have two Division
(i) Agnatha (Lacks Jaw):
→ Class : Cyclostomata
→ Live as ectoparasites on some fishes.
→ Have sucking and circular mouth withut jaws.
→ Have 6-15 paris of gill slits for respiration.
→ No scales, no paried fins.
→ Cranium and vertebral column is cartilagenous.
→ Marine, Migrate to fresh water for spawning and die after spawning.
→ Larva returns to ocean after metamorphosis.
→ Example: Petromyzon, Myxine
(ii) Gnathostomata (Bear Jaws)
→ Divides into two super classes:
(a) Super Class: Pisces(b) Super Class: Tetrapoda
(a) Super-class: Pisces
(i) Class: Chondrichthyes
→ Have cartilagenous endoskeleton, are marine with streamlined body.
→ Mouth ventral.
→ Gill slits withut operculum (gill cover).
→ Skin has placoid scales; jaws–very powerful.
→ No air bladder, so swim constantly to avoid sinking.
→ Teeth are backwardly directed, modified placoid scales.
→ Notochord is persistent throughout life.
→ Two chambered heart; poikilotherms (cold-blooded)
→ Sexes separate; males have claspers on pelvic fins.
→ Internal fertilisation; viviparous.
→ Example: Tarpedo, Trygon, Scoliodon, Pristis, Carcharodon
(ii) Class: Osteichthyes
→ Have bony endoskeleton, Aquatic
→ Mouth is usually terminal. Body-Streamlined
→ Four pairs of gill slits covered by operculum, heart two chambered, cold blooded.
→ Sking has cycloid/ctenoid scales.
→ Have air bladder which regulates buoyancy.
→ Sexes separate.
→ Usually oviparous, fertilisation external.
→ Development direct.
→ Example: Hippocampus, Labeo, Catia, Betla, Clarias, Exocoetus
Sub-Phylum Vertebrata : Gnathostomata
(b) Super Class: Tetrapoda
(i) Class: Amphibia
→ Can live in aquatic as well as terrestrial habitats.
→ Body divisible into head and trunk, paired limbs.
→ Skin moist. No scales.
→ Tympanum represents ear. Eyes have eyelids.
→ Cloaca is the common chamber where alimentary canal, urinary and reproductive tracts open.
→ Respiration by gills, lungs or skin.
→ Heart is 3-chambered; cold-blooded; Sexes separate; fertilisation external.
→ Oviparous. Indirect development.
→ Example: Bufo, Rana, Hyla, Salamandra, Ichthyophis
(ii) Class: Reptilla
→ Creep or crawl to locomote. Mostly terrestrial.
→ Body has dry and cornified skin and epideremal scales or scutes.
→ Tympanum represents ear.
→ Limbs, when present, are two pairs
→ Snakes and lizards shed, scales as skin cast.
→ Heart 3-chambered but 4-chambered in crocodiles.
→ Sexes Separate; fertilisation internal.
→ Oviparous. Direct development.
→ Example: Testudo, Naja, Vipera, Calotes, Crocodilus, Hemidactylus
(iii) Class: Aves
→ Presence of feathers except flihtless birds and beak (modified jaws) without teeth.
→ Forelimbs are modified into wings.
→ Hind limbs have scales, mofidied for walking, swimmng or clasping.
→ Skin is dry as no glands on skin except oil gland (preen gland) at base of tail.
→ Endoskeleton bony with air cavities (pneumatic) and hollow bones to assist in flight.
→ Crop and Gizzard—Additional chamber in digestive tract.
→ Air sacs are connected to lungs to supplement respiration.
→ Warm blooded (homoiothermous), Heart–Four chambered.
→ Oviparous. Direct development.
→ Example: Columba, Struthio, Pavo, Corvus, Neophron, Pstittacula Aptenodytes.
(iv) Class: Mammalia
→ Have mammary glands to nourish young ones.
→ Have two pairs of limbs, adapted to perform special work.
→ Skin has hairs.
→ External ears or, pinna present.
→ Different types of teeth in jaw.
→ Homoiothermous; Heart–Four chambered, Lungs for respiration.
→ Sexes are separate, fertilisation internal.
→ Viviparous. Direct development.
→ Example: Rattus, Canis, Elephas, Equus. Oviparous mammal is Ornithorhynchus.
NCERT Solutions of Class 11 Animal Kingdom