Animal Kingdom- Animalia, Subphylum

R.H. Whittaker organized the organisms into five kingdoms. He classified organisms on the basis of cell structure, mode, and source of nutrition and body design. The five kingdoms proposed by Whittaker are Monera, Protista, Fungi, Plantae, and Animalia. Let’s learn about the animal kingdom i.e., kingdom Animalia.

Kingdom Animalia

Kingdom Animalia consists of all animals. The animal kingdom is the largest kingdom among the five kingdoms. Animals are multicellular eukaryotes. But they don’t have a cell wall or chlorophyll like plants. Hence, members of the animal kingdom have a heterotrophic mode of nutrition. Kingdom Animalia has been classified into 10 different subphyla based on their body design or differentiation.

The different subphylum of the animal kingdom are as follows:

  1. Porifera
  2. Coelenterata (Cnidaria)
  3. Platyhelminthes
  4. Nematoda
  5. Annelida
  6. Arthropoda
  7. Mollusca
  8. Echinodermata
  9. Protochordata
  10. Vertebrata

Subphylum Porifera

Porifera means organisms with holes. They are commonly known as Sponges. Features of the poriferan are:

  1. Non-motile, multicellular organisms with the hard outer skeleton.
  2. Have a porous body.
  3. Pores on the bodies create a canal system which helps in circulation of substances.
  4. Not differentiated into head and tail; don’t have a well-developed organ or organ system.
  5. Include MarineHabitat.
Sponges

Sponges

Example of subphylum Porifera includes- Spongilla, Sycon, etc.

Subphylum Coelenterata (Cnidaria)

The term Coelenteratais derived from the Greek word “kilos” which means hollow-bellied. Their features are:

  1. Have a hollow body cavity.
  2. The body is differentiated into two ends.
  3. Includes all aquatic animals.
  4. The body is made of two layers of cells: inner and outer linings.
  5. Live in colonies (corals) as well as solitary (Sea anemone).
Coelenterata

Hydra

Example of subphylum Coelenterata includes – Hydra, Jellyfish, etc.

Subphylum Platyhelminthes

Platyhelminthes are commonly known as flatworms. Their features are:

  1. Dorsoventrally flattened body.
  2. Complex and have differentiated body structure.
  3. Tissues are differentiated from three layers of cells and are triploblastic.
  4. Don’t have true internal cavity or coelom.
  5. Have bilateral symmetry.
  6. Either free-living (Planaria) or parasitic (Liver flukes).
Platyhelminthes

Flatworm

Example of subphylum Platyhelminthes includes -Tapeworm, Planaria, etc.

Subphylum Nematoda

Phylum Nematoda consists of nematodes or roundworms. Their features are:

  1. Nematodes have a cylindrical body.
  2. Bilaterally symmetrical and triploblastic.
  3. Have pseudocoelom, a false body cavity.
  4. Parasitic and causes diseases such as elephantiasis, ascariasis, etc.
 Nematoda

Ascaris

Example of subphylum Nematoda includes – Ascaris, Wuchereria, etc.

Subphylum Annelida

Annelids are commonly known as segmented or ringed worms. They have the following features:

  1. Have a segmented cylindrical body.
  2. The body is differentiated into head and tail.
  3. Bilaterally symmetrical and triploblastic.
  4. Have a true body cavity.
  5. Habitat: marine, freshwater, and land.
 Annelida

Nereis

Example of subphylum Annelida includes – Earthworm, Leech, etc.

Subphylum Arthropoda

Arthropod means jointed legs. Animals which have jointed appendages belong to this phylum. This is the largest phylum in the animal kingdom. Other features are:

  1. They are bilaterally symmetrical.
  2. Have jointed appendages, exoskeleton, and a segmented body.
  3. Have well-differentiated organ and organ system.
  4. Have an open circulatory system, but don’t have differentiated blood vessels.
Arthropoda

Spider

Example of subphylum Arthropoda includes – Spiders, butterflies, and mosquitoes.

Subphylum Mollusca

Phylum Mollusca consists of a large group of animals. Features are:

  1. Bilaterally symmetrical and triploblastic.
  2. Less segmented body.
  3. Well-developed organ and organ system.
  4. Open circulatory system.
  5. Limbs are present.
Mollusca

Mollusc

Example of subphylum Mollusca includes- Snails and octopus.

Subphylum Echinodermata

The term Echinodermata is derived from the Greek words, echinos meaning hedgehog and derma meaning skin. Thus, echinoderms are spiny-skinned animals.

  1. Radial symmetry and triploblastic.
  2. Have true coelom.
  3. Have hard calcium carbonate skeleton structure.
  4. Free-living marine animals.
Echinodermata

Starfish

Example of subphylumEchinodermata includes- Sea urchins, starfish, etc.

Subphylum Protochordate

Protochordates have the following features:

  1. Bilaterally symmetrical and triploblastic.
  2. Have true coelom.
  3. Habitat: marine.
  4. The notochord is present at some stages of lives.
Protochordata

Amphioxus

Example of subphylum Protochordates includes- Balanoglossus, etc.

The notochord is a long supporting structure that separates the nervous tissues from the gut. It runs along the back of an animal and is a place for muscle attachment that helps in movement.

Subphylum Vertebrata

Phylum Vertebrata consists of animals with a true vertebral column. They have an internal skeleton where muscles are attached and help in movement. Other features are:

  1. Bilaterally symmetrical, triploblastic, coelomates and the segmented body.
  2. The body design is complex and well-differentiated.
  3. The body has an organ and organ system level of organization.
  4. Possess notochord.

Vertebrates are further grouped into five classes. They are-Pisces, Amphibia, Reptilia, Aves, Mammalia.
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Practise This Question

The animals that have a true vertebral column and an internal skeleton are called vertebrates.