Biology - Animalia Kingdom

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Introduction

• The organisms, which are eukaryotic, multicellular, and heterotrophic, are categorized as Animalia kingdom.

• The organisms of Animalia kingdom have no cell-wall.

• Most of animals of Animalia kingdom are mobile.

Classification of Animalia Kingdom

• Based on the extent and type of the body design differentiation, Animalia kingdom classified as −

  • Porifera

  • Coelenterata

  • Platyhelminthes

  • Nematoda

  • Annelida

  • Arthropoda

  • Mollusca

  • Echinodermata

  • Protochordata

  • Vertebrata

    • Pisces

    • Amphibia

    • Reptilia

    • Aves

    • Mammalia

• Let’s discuss each of them in brief −

Porifera

• The literal meaning of ‘porifera’ is the organisms with holes.

• The organisms of porifera are non-motile and attached to some solid support.

• The examples of this group are Sycon, Spongilla, Euplectelia, etc.

Coelenterata

• Organisms of coelenterata group live in water.

• The organisms of this group have cavity in their bodies.

• Hydra and sea anemone are the common example of coelenterate.

Platyhelminthes

• The organisms of this group do not have true internal body cavity or coelom; so, they neither have well-developed organs.

• The bodies of organisms of this group are flattened from top to bottom; therefore, they are also known as flatworms.

• Planareia, liverfluke, tape worm, etc., are the typical examples of this group.

Nematoda

• The organisms of nematode have cylindrical body.

• The organisms have tissue, but as such no well-developed body (i.e. no real organ).

• The filarial worms (causing elephantiasis disease), roundworm in the intestines, etc., are the common examples of nematodes.

Annelida

• The organisms of annelida group live almost everywhere including fresh water, marine water as well as on land.

• Earthworms, nereis, and leeches are the familiar examples of annelida.

Arthropoda

• Arthropoda, probably, is the largest group of animals.

• The animals of this group don’t have well defined blood vessels rather there is an open circulatory system.

• The literal meaning of arthropod is jointed legs; so, they have jointed legs.

• Prawns, butterflies, houseflies, spiders, scorpions, etc. are the typical examples of arthropod.

Mollusca

• The organisms of mollusca are invertebrate.

• Most of the organisms of Mollusca group live in water.

• Snails and mussels are the typical example of Mollusca.

Echinodermata

• The organisms of Echinodermata have spiny skinned.

• Echinodermata are free-living marine organisms.

• The examples of echinodermata are starfish, sea urchins, feather star, etc.

Protochordata

• The organisms of protochordata are normally marine. E.g. Balanoglossus, Herdemania, and Amphioxus

• The organisms of protochordata show a typical feature of body design, called as notochord; however, it does present there throughout the life.

Vertebrata

• Vertebrata has been discussed in a separate chapter.