Skip to main content

🎓 New resources added daily! Join over 50,000 students using Padandas

Animalia | NEB Class 11 Biology

Overview
Subject

Animalia | NEB Class 11 Biology

Kingdom Animalia for NEB Class 11 Biology: classification terms and diagnostic features of major phyla from Porifera through Chordata.

Sep 4, 2026
9,288

8.2 Kingdom Animalia

Important terms used in characters and classification of organisms

1) Cellularity

The organisms are made up of cells, called as basic units of life. Organisms may be of two types:

  • Unicellular: Organisms made up of only one cell are called unicellular. eg: Protozoans
  • Multicellular: Organisms made up of many cells. They are also called metazoans. eg: all organism except protozoans.

2) Body layer

  • It is the cellular layers which form the covering of the body. Its two types:
  • Diploblastic: This term is used for those animals which are derived from two germ layers: outer-ectoderm & inner-endoderm eg. sponges
  • Triploblastic: This term is used for those animals which are derived from three germ layers: outer-ectoderm, middle-mesoderm and inner-endoderm.

3) Body organization surfaces

  • Anterior end: The part of the body usually contains the mouth.
  • Posterior end: The part of the body usually contains an anus.
  • Dorsal surface: It is the upper surface of the body which faces towards the sky in natural posture.
  • Ventral surface: It is the under surface of the body which faces towards the ground in natural posture.
  • Laterally compressed: It is the body which is flattened from both lateral sides.

4) Symmetry

  • Bilateral symmetry: Body can be divided into two exactly equal and similar halves.
  • Radial or Biradial: Body is cut from any sides passing through the central axis and divided into two exact halves.
  • Asymmetry: Body plan is in such a way that the animal cannot be cut into two equal halves.

5) Habitat

  • Aquatic: The organisms which live only in water. It may of two types:
    • Fresh water: It is the organism which lives in fresh water.
    • Marine organism: It is the organism which lives in a sea water.
  • Amphibious: The animals which can live both on land and in water.
  • Terrestrial: The animals which live only on land.

6) Body Temperature

  • Cold blooded (Poikilothermic): The animals whose body temperature is variable according to the environment.
  • Warm blooded (Homeothermic): The animals whose body temperature is not variable according to the environment.

Coelom or Body cavity

Coelom is defined as the cavity found in between the body wall and the alimentary canal wall.

Locomotion

  • It is the process of movement of organism from one place to the other.
  • Pseudopodia: These are the cytoplasmic process found in the Amoeba etc.
  • Flagella: These are long, whip-like, cytoplasmic processes found in Euglena.
  • Cilia: These are small, cytoplasmic found in Paramecium etc.
  • Setae: These are the locomotory organs of earthworms.
  • Parapodia: These are locomotory organs of arthropoda.
  • Appendages: These are locomotory of arthropods.
  • Muscular foot: These are locomotory of molluscs.
  • Tube feet: These are locomotory of starfish.
  • Fins: These are the locomotory organs of fish.
  • Limbs: These are the locomotory organs of vertebrates.

10) Nutrition

  • It is the process of obtaining food
  • Holozoic: An organism takes food in solid form. It is also called animal like i.e. heterotrophs.
  • Holophytic nutrition: It is plant-like nutrition.
  • Saprozoic nutrition: The animals fed on dead organic matter. Earthworm
  • Saprophytic nutrition: The plants feed on dead organic matter. Fungi
  • Parasitic nutrition: The organisms which live on other organisms and remain alive at the expense of host. Tapeworm
  • Carnivorous: These animals feed on animal flesh.
  • Herbivorous: These animals feed on plants.
  • Omnivorous: These animals feed on plants as well as animals.

Digestion

It is the process of breaking down the complex foods chemically and mechanically. Its two types:

  • Intracellular digestion: It is the type of digestion which takes place inside the cell.
  • Extracellular digestion: It is the type of digestion which takes place outside the cell.

11) Respiration

It is the process of taking oxygen to oxidise the simpler foods in order to release energy. It is an energy releasing process. Its two types

  • Aerobic respiration: It takes place in presence of oxygen
  • Anaerobic respiration: It takes place in absence of oxygen

13) Circulation

It is the process of flow of fluid (blood) within the body. Its two types are:

  • Open circulation: It is the type of circulation in which blood remains in the large open sinuses.
  • Closed circulation: It is the type of circulation in which blood flows through the closed blood vessels

Types of Heart

  • Neurogenic heart: It is found in all invertebrates except echinodermata
  • Myogenic heart: It is found in echinodermata and all chordata.

14) Excretion

It is the process of removal of waste substances from the body. The excretory organs in various organism are:

  • Contractile vacuole: It is found in protozoans
  • Flame cell: It is found in helminths
  • Nephridia: It is found in annelids
  • Malpighian tubule: It is found in arthropods
  • Organ of Bojanus: It is found in mollusca
  • Kidney: It is found in vertebrates.

15) Reproduction

  • It is the process of giving young ones.
  • Asexual reproduction: It takes place by one parent only.
  • Sexual reproduction: It is a type of reproduction in which male & female sexes are involved male & female gametes are fused to form zygote.

Fertilization

  • It is the process of fusion of male & female gametes which result in the formation of zygote.

Phylum: Porifera

(poros = pore; ferre = to bear)

Study of sponges is called parazoology.

General characters of phylum porifera

  1. Important character: Body possesses numerous minute pores called ostia and single large osculum.
  2. Habitat: They are all aquatic, mostly marine and few freshwater.
  3. Organism: They are first multicellular.
  4. Symmetry: They are mostly asymmetrical. Some are radially symmetrical.
  5. Body layer: Body wall is diploblastic.
  6. Coelom: They are acoelomate animals.
  7. Water canal system: It is well developed.
  8. Nutrition: It is holozoic type.
  9. Digestion: It is intracellular.
  10. Respiratory: Ostia acts as mouth & osculum as anus.
  11. Skeleton: Body is supported by spicules & skeletons which are made up of CaCO3.
  12. Reproduction: It is asexual by budding or gemmule formation.
  13. Nervous system: It is absent.
  14. Cross-fertilization: It is very common.
  15. Regeneration: They have the great power of regeneration.
  16. Development: It is indirect

Classification

  • It is classified into three classes on the basis of chemical nature of spicules.
  1. Calcarea — Spicules are made up of calcium carbonate (CaCO3). Eg: Sycon, Leucosolenia
  2. Hexactinellida — Spicules are made up of silica. Eg: Euplectella, Hyalonema
  3. Demospongia — Spicules are made up of spongin fibres. Eg: Spongilla, Euspongia

Phylum: Coelenterata (Cnidaria)

Study of Coelenterata is called Cnidology.

General characters of phylum Coelenterata

  1. Important character: Body possesses an internal hollow cavity or gastrovascular cavity.
  2. Habitat: They are all aquatic, mostly marine and some fresh water.
  3. Symmetry: They are usually radially symmetrical.
  4. Body organization: They are multicellular organisms
  5. Germ layer: They are in diploblastic.
  6. Nutrition: It is holozoic type.
  7. Digestion: It is intracellular as well as extracellular.
  8. Coelom, respiratory, circulatory & excretory organ: are absent
  9. Respiration & Excretion: It takes place through general body surface.
  10. Reproduction: They reproduce both by asexually and sexually.

Classification

It is classified in three classes on the basis of presence and absence of reproductive forms.

  1. Hydrozoa — Both polyp & medusa forms are present. They are diploblastic. E.g.: Hydra, Obelia etc.
  2. Scyphozoa — Medusa form is dominant. They are diploblastic. Eg: Aurelia, Rhizostoma
  3. Anthozoa — Only polyp form is present. They are triploblastic. Eg: Metridium, Pennatula

Phylum: Platyhelminthes

Its study is called Helminthology.

General characters of phylum platyhelminthes

  1. Important character: Body is dorso-ventrally flattened.
  2. Symmetry: They are bilaterally & triploblastic.
  3. Coelom: They are acoelomate, animals.
  4. Digestive system: It is incomplete and branched or absent
  5. Respiratory system: They are absent.
  6. Excretory system: They have an excretory organ flame cell.
  7. Nervous system: It is primitive & a ladder like
  8. Reproductive system: It is well developed
  9. Fertilization: It is internal, may be cross or self.

Classification

It is classified into three classes on the basis of both habit and segmentation

  1. Turbellaria — Free living aquatic forms; Unsegmented body; Eg: Planaria
  2. Trematoda — Exclusively parasites; They have unsegmented and leaf-like body; Eg: Fasciola hepatica
  3. Cestoda — Exclusively endoparasites; Segmented body like tape; Eg: Taenia solium

Phylum: Nemathelminthes

Study of nematodes is called Nematology.

General characters of Nemathelminthes

  1. Important character: These are cylindrical, elongated, unsegmented and worm like.
  2. Habitat: These are mostly parasitic and some free living found in soil and water.
  3. Body layer: They are triploblastic.
  4. Coelom: It is pseudo coelom type.
  5. Nutrition: Nutrition is holozoic type.
  6. Symmetry: They are bilaterally symmetrical.
  7. Digestive system: Alimentary canal is complete and straight.
  8. Respiratory system: It is absent.
  9. Circulatory system: Specific blood vascular is lacking.
  10. Excretory system: It consists of lateral excretory ducts which collect the excretory substances and expel out through excretory pore.
  11. Nervous system: It consists of a nerve ring and a longitudinal nerve cord.
  12. Reproductive system: These are unisexual or dioecious.
  13. Fertilization: It is internal.

Classification

It classified into two classes on the basis of presence and absence of amphids:

  1. Phasmida — Caudal sense organ (phasmids) is present. Most of them are parasitic forms. Eg: Ascaris
  2. Aphasmida — Caudal sense organ (phasmids) is absent. Most of them are free living forms. Eg: Rotifers

Difference between Male Ascaris & Female Ascaris

MaleFemale
It is smaller than female.It is longer than male.
It has cloaca.It has anus
Tail consists a pair of penial setae.Tail is without penial setae
It is straight.

Phylum: Annelida

General characters of phylum annelida

  1. Important characters: They are elongated metamerically segmented.
  2. Habitat: They are mostly aquatic and some are terrestrial and burrowing.
  3. Germ layer: They are triploblastic.
  4. Symmetry: They are bilaterally symmetrical.
  5. Coelom: It is true coelom type formed by mesoderm.
  6. Locomotion: It takes place by setae & parapodia (in Nereis) or suckers (in Leech).
  7. Nutrition: It is holozoic type.
  8. Digestive system: Alimentary canal is straight and well developed.
  9. Respiration: It takes place through moist body surface by diffusion.
  10. Circulation: Blood vascular system is closed type consisting of hearts and blood vessels.
  11. Excretion: It takes place through nephridia.
  12. Nervous system: It consists of a pair of cerebral ganglia.
  13. Reproduction: They are usually hermaphrodite

Classification

  • It classified into three class on the basis of locomotory organ:
  1. Polychaeta — locomotory organ is parapodia; E.g.: Nereis
  2. Oligochaeta — Locomotory organ is setae; Eg: Pheretima
  3. Hirudinea — Locomotory organ is suckers; Eg: Hirudinaria
  4. Archiannelida — Segmentation is internal only; Eg: Polygordius

Phylum: Arthropoda

Study of insect called entomology

General characters of phylum arthropoda

  1. Important character: Body consists of jointed appendages or legs.
  2. Habitat: This is the largest phylum
  3. Symmetry / Germ layer: These are triploblastic
  4. Locomotion: It takes place by paired lateral jointed appendages.
  5. Body division: Body is divisible into head; thorax and abdomen.
  6. Coelom: It is haemocoelom type
  7. Cephalisation: A true head is present.
  8. Sensory organs: These include antennae, compound eye, statocytes etc.

Classification

It is classified on the basis of number of locomotory organ.

  1. Crustacea — Five pairs of walking legs; Respiration by gills; Eg: Prawn
  2. Insects or Hexapoda — Three pairs of walking legs; Respiration by trachea; Eg: Cockroach
  3. Myriapoda — Many pairs of walking legs; Respiration by trachea; Eg: Julus
  4. Arachnida — Four pairs of walking legs; Respiration by book lung and trachea; Eg: Spider.

Phylum: Mollusca

It is the second largest phylum. The study of molluscs is called malacology and study of shells of molluscan.

General characters of phylum mollusca

  1. Important characters: Body is soft, unsegmented and without appendages.
  2. Habitat: They are mostly freshwater or marine and few are terrestrial
  3. Body layers: They are triploblastic
  4. Symmetry: They are bilaterally symmetrical.
  5. Coelom: They are haemocoelomate animals
  6. Locomotion: It takes place by ventral muscular foot.
  7. Excretion: It takes place by paired kidney.
  8. Reproductive system: Sexes are usually separated but some are hermaphrodite
  9. Sense organs: These are eyes, tentacles, osphradium.

Phylum: Chordata

General characters of phylum chordata

  1. Presence of notochord at some stage of development
  2. Presence of dorsal tubular nerve cord
  3. Presence of lateral gills slits on either side of the pharynx at some stage of development
  4. Presence of post-anal tail
  5. Presence of ventrally situated heart

General characters of Pisces

  1. Habitat: They are completely aquatic found in the freshwater and marine water.
  2. Habit: It is cold blooded or poikilothermic
  3. Locomotion: It takes place by paired and unpaired fins.
  4. Respiratory system: It takes place by gills
  5. Reproductive system: Sexes are unisexual.
  6. Eg: Sea horse

General characters of amphibia

  1. They are amphibious, live in both water and land.
  2. Skin is moist, thin, smooth, glandular.
  3. Body temperature is cold-blooded
  4. Body is cylindrical and divided into head and trunk
  5. Locomotion takes place by pentadactyle limbs.
  6. Eg: Frog

General characters of reptilia

  1. They are elongated, cylindrical and can walk by crawling.
  2. They are mostly terrestrial and some are aquatic
  3. Skin is dry, rough and non-glandular
  4. Body temperature is cold-blooded
  5. Locomotion takes place by two pairs of pentadactyle limbs
  6. Eg: Wall lizard

General characters of aves

  1. Body is covered with feathers adapted to live in air
  2. Temperature are warm-blooded
  3. Locomotion takes place by two pairs of limbs.
  4. A prominent beak is present without teeth
  5. Skin is dry without glands.
  6. Eg: Parrot

General characters of mammalia

  1. Body is elongated, covered with hair.
  2. They live in all habitat.
  3. Body is divided into head, neck, trunk, tail
  4. Locomotion takes place by two pairs of pentadactyle limbs
  5. Reproduction are separate
  6. Fertilization is internal
  7. Excretory system takes place by kidney
  8. Eg: Rabbit

About National Examinations Board

This content is part of Biology offered by National Examinations Board. This institution is committed to providing high-quality educational resources.

Protista Earthworm

Frequently Asked Questions

This content is carefully structured to build understanding progressively, starting with fundamentals and advancing to more complex concepts.

Yes, once you have access, you can revisit this Animalia content as many times as you need.

Practice exercises and examples are integrated throughout the content to reinforce your understanding of Animalia.

Ready to Master Animalia | NEB Class 11 Biology?

Continue your learning journey in NEB Class 11 Biology : Complete Notes , Q&A Solutions and Videos and explore more comprehensive educational content.

Explore More Biology View All Subjects