General Characters of All Classes of Vertebrates.


The major classes of vertebrates are Cyclostomata, Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, and Mammalia. The general characteristics of these phyla are given below:

Cyclostomata

  • The body is slender, rounded, and eel-like.
  • They are aquatic.
  • Their skin is naked meaning no scales are present.
  • Fish-like in form.
  • True jaws are absent.
  • Paired appendages are lacking.
  • Gills are the respiratory organs.
  • Example: Petromyzon (lamprey).

Chondrichthyes

  • All are marine species.
  • Their skeleton is cartilaginous.
  • Their skin contains placoid scales.
  • On both sides of the head, 5-7 pairs of gills are present.
  • The body is streamlined so that it can move faster in the water.
  • The tail is heterocercal.
  • No operculum is present.
  • Example: Scoliodon, Swordfish, etc.

Osteichthyes

  • They are mostly freshwater fish.
  • Their skin contains cycloid, ctenoid, or ganoid scales. Some of them has no scales.
  • Four pairs of gills are present on both sides of the body.
  • Gills are covered with bony operculum.
  • The skeleton is bony; not cartilaginous like Chondrichthyes.
  • Gills are the primary respiratory organs.
  • The digestive system is complete.
  • Fertilization is external.
  • Example: Labeo rohita, Tenualosa ilisha, Ompok pabda, Mystus tengara, Mystus cavasius, Anabas testudineus, Puntius ticto, etc.

Amphibia


Reptilia

  • The skin is dry and contains scales as an exoskeleton.
  • They move by crawling.
  • They have two forelimbs and two hindlimbs except for snakes.
  • Each limb contains five claws.
  • The digestive system is complete.
  • They lay eggs. Fertilization is internal.
  • They are the first fully terrestrial animals.
  • Example: Lizard, Snake, Crocodile, etc.

Aves

  • The body is covered with feathers.
  • Feather is their unique character.
  • Two forelimbs and two hindlimbs are present. Forelimbs are modified into wings.
  • They have air sacs around their lungs which help them in flight.
  • The digestive system is complete.
  • They have crop in their digestive system where the food is temporarily stored.
  • They are warm-blooded.
  • Their heart is four-chambered.
  • Their bones are light, strong, delicate, and laced with air cavities.
  • Example: Columba livia (Pigeon), Crow, etc.

Mammalia

  • Their body is covered with hairs.
  • They have two forelimbs and two hindlimbs.
  • Female mammals have mammary glands which produce milk.
  • They are warm-blooded animals.
  • Their heart is four-chambered.
  • Their teeth are heterodont.
  • All mammals give birth to the child.
  • Example: Cavia porcellus (Guinea pig), Royal Bengal Tiger, etc.

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