11TH BCLASSIOLOGY CHAPTER- 4 ANIMAL KINGDOM NCERT QUICK REVISION NOTES FOR NEET AND CBSE EXAM

ANIMAL KINGDOM

POINTS TO REMEMBER IN THIS CHAPTER

BASIS OF CLASSIFICATION:

Animals are classified on the basis of following few fundamental features.

1. Levels of Organisation :

(1) Cellular level: Cells are arranged as loose cell aggregates, e.g., sponges,

(2) Tissue level: The cells performing the same function are arranged into tissues, e.g.,  Coelenterates. 

(3) Organ level: Tissues are grouped together to form organs, each specialised for a particular function. e.g., platyhelminthes. 

(4) Organ system level: organs are associated to  form functional systems eg., Annelida 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).

2. Symmetry:

• Asymmetrical: Cannot be divided into equal    halves through median plane e.g., Sponges.

• Radialsymmetry: Any plane passing through  central axis can divide organism into identical halves. e.g., coelentrates, Ctenophores and      echinoderms.

• Bilateralsymmetry: Only one plane can divide the organism into two identical left and right halves e.g.. Annelids and Arthropods.

3. 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) 

e.g., porifers and Coelentrates. (Cnidarians)

Triploblastic: Three layers present in developing embryo i.e., ectoderm. mesoderm and endoderm. 

e.g., Platyhelminthes to Chordates.

4. Coelom:(Body cavity which is lined by mesoderm) 

Coelomates: Have coelome.g., Annelids, Arthropods, molluscs, Echinoderms, Chordates etc.

Pseudocoelomates: No true coelem as mesoderm is present in scattered pouches between ectoderm and endoderm. e..g., Aschelminthes. 

Acoelomates: Body cavity is absent e.g., Platyhelminthes.

5. Segmentation :

(A) True Metamerism Found 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 e.g., Earthworm. (B) Pseudometamerism: Found in tapeworm. The proglottids (segments of tapeworm) budded off from neck not emryonic in origin.

6. Notochord :

• Rod-like structure formed during embryonic development on the dorsal side. It is mesodermally derived e.g.. Chordates. 

• Non-chordates do not have notochord.e.g., 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) e.g., 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. e.g. corals.

• exhibit two body forms: polyp and medusa e.g., Hydra, Aurelia. 

• Alternation of generation between body forms called metagenesis ocurs in Obelia where :

Medusa (free swimming & umbrella shaped) change Sexually into Polyp. (Sessile and cylindrical)

Polyp. (Sessile and cylindrical) change Asexually into Medusa (free swimming & umbrella shaped)

e.g., 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.

e.g., 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. e.g.. 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. eg.. Ascaris, Wuchereria, Ancylostoma.

PHYUM 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.

• eg., 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. 

e.g., 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.

eg., 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)

• e.g., 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.

eg. 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.

 e.g., Ascidia, Salpa, Doliolum

(ii) Sub-phyla Cephalochordata

• Notochord extends from head to tail (Persistent)

 e.g., 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:

(a) 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.

e.g., Petromyzon, Myxine

(b) Gnathostomata (Bear Jaws)-divides into two super classes :

(i) SUPER-CLASS : PISCES

1. 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.

e.g., Tarpedo, Trygon, Scoliodon, Pristis, Carcharodon

2. 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.

• eg.. Hippocampus, Labeo, Catia, Betla, Clarias, Exocoetus

SUB-PHYLUM VERTEBRATA: GNATHOSTOMATA

(ii) SUPER CLASS : TETRAPODA

1. 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. 

e.g., Bufo, Rana, Hyla, Salamandra, Ichthyophis

2. 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.

• eg., Testudo, Naja, Vipera, Calotes, Crocodilus, Hemidactylus

3. 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.

• eg. Columba, Struthio, Pavo, Corvus, Neophron, Pstittacula Aptenodytes.

4. 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.

• e.g., Rattus, Canis, Elephas, Equus. Oviparous mammal is Ornithorhynchus.

CLASS 11TH BIOLOGY CHAPTER- 5 MORPHOLOGY OF FLOWERING PLANTS FOR NEET AND CBSE EXAM LINK