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General Characters of All Phylum of The Invertebrates.

Invertebrates are a group of animals that lack a backbone or vertebral column. There are over 30 phyla of invertebrates, but some of the most common and important phyla include:



  • The members of this phylum are commonly known as ‘Sponge’.
  • They are found all over the world.
  • They are exclusively marine. Only a few live in freshwater.
  • They are colonial.
  • They are multicellular animals.
  • Their body wall contains numerous pores.
  • Food and oxygen enter the body through the pores of the body wall.
  • Their body has no compact tissue, organ, or organ system.
  • Example: Spongilla etc.


  • This phylum was previously known as Coelenterata.
  • They are present almost all over the world.
  • They are mostly marine. But many species live in freshwater too.
  • They are diverse in shape, size, and color.
  • Some of them are solitary and some are colonial.
  • The body consists of two embryonic layers: epidermis or ectoderm and gastrodermis or endoderm.
  • Between the two layers; a gelly-like layer is present called Mesoglea which is not a true layer.
  • The body cavity is known as the coelenteron.
  • The coelenteron helps in digestion and circulation.
  • Epidermis bears cnidoblast which is a special type of cell.
  • Example: Obelia, Hydra, etc.


  • They are mostly parasitic.
  • Some of them are ecto-parasite and some of them are endo-parasite.
  • Some free-living species live in fresh and saline water. And some of them also live in wet and damp soil.
  • Their body is flat.
  • They are bisexual.
  • The body is covered with a thick cuticle.
  • The body contains a sucker and hooks.
  • The flame cell is the excretory organ.
  • The digestive system is incomplete.
  • Example: Taenia solium, Liver fluke, Ascaris lumbricoides etc.


  • This phylum is also called the Nemathelminthes.
  • Their body is tubular and cylindrical.
  • The body is covered with thick skin.
  • Their digestive system is complete as the digestive system starts from the mouth and ends at the anus.
  • Respiratory and circulatory systems are lacking.
  • They are unisexual.
  • The true coelom is absent.
  • Example: Roundworm.


  • They are mostly found in the temperate and tropical regions of the world.
  • Their body is tubular.
  • The body is segmented.
  • Each segment bears setae that help the annelids in locomotion.
  • Nephridia is their excretory organ.
  • Example: Hirudinaria granulosa (Leech), Earthworm, etc.


  • It is the largest phylum of the animal kingdom because it contains the largest number of species.
  • They can live everywhere in the world.
  • Some of them are parasitic and some of them are free-living.
  • Many species of this phylum contain wings that help them fly.
  • Their body is segmented.
  • Their body bears joint appendages.
  • A pair of compound eyes and antennae are present on the head.
  • The body is covered with a hard chitinous exoskeleton.
  • The body cavity is filled with blood. Their blood is known as haemocoel.
  • Example: Prawn, Cockroach, Hermit crab, etc.


  • They live in almost all environments of the world.
  • They are soft-bodied.
  • Their body is covered with a hard shell.
  • They use their muscular foot for locomotion.
  • They respire with their lungs or gills.
  • Example: Pila globosa (Snail), Mussel, etc.


  • They are exclusively marine. No freshwater species are present.
  • They live in all seas and oceans of the world.
  • Their dermal skin bears spines.
  • The body is divided into five equal parts.
  • A unique water vascular system is present.
  • They move with the help of their water vascular system.
  • No distinct head is present.
  • No dorsal and ventral surface is present. They have oral and aboral surfaces.
  • Example: Asterias (Sea Star), Sea cucumber, etc.
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