Vertebrata General Characteristics, Classification and Examples | Free Biology Notes

Vertebrata General Characteristics, Classification and Examples

After reading this article you will learn about Vertebrata General Characteristics, Classification and Examples

Vertebrata General Characteristics

  • Presence of brain box and vertebral column
  • Notochord initially is embryonic, replaced by vertebral column in adult
  • The circulatory system is closed with ventral chambered heart
  • The blood plasma contains RBC and WBC
  • Gill slits are limited in number (usually 5 pairs)
  • Two pairs of appendages present
  • Nerve cord is differentiates into brain and spinal cord

Classification of Vertebrata

Subphylum vertebrata is divided into 2 divisions such as, Agnatha, the division which lacks jaw and Gnathostomata, the division which bears jaw.

Division 1. Agnatha

  • Most of the members of this class are marine
  • These fishes are ectoparasite as well as scavenger
  • They have elongated body with 6-15 pairs of gills slits for respiration
  • They have a sucking and circular mouth without jaws
  • Scales and paired fins absent
  • Notochord and vertebral column both are present. bones are absent
  • Circulation is closed type, 2 chambered heart.
  • Animals unisexual, fertilization external and larval stage is absent
  • E.g. Petromyzon, Myxine etc.

Division 2. Gnathostomata

  • Two well formed jaws encircle the mouth aperture in all members of this group.
  • Paired and in some cases jointed appendages are present in Gnathostomata.
  • Calcified, bony skull and vertebra are characteristic features of Gnathostomata.
  • Divided into 2 super classes:- Pisces and Tetrapoda

Superclass 1. Pisces

  • All aquatic and cold blooded fishes
  • Body is long, spindle shaped and streamlined, which is divided into head, trunk and tail
  • Body is covered by dermal scales, denticles or bony plates
  • Locomotion with the help of various fins
  • Respiration by gills
  • Heart is two chambered, having one auricle and one ventricle
  • External and middle ears are absent
  • Lateral line system is well developed. help to sense water current vibrations
  • Fishes are unisexual. Fertilization is internal or external and Development is direct
  • Oviparous, viviparous or ovoviviparous
  • Super class Pisces classified into two classes:- Chondrichthyes and Osteichthyes

Superclass 2. Tetrapoda

  • Tetra-four, podos-feet
  • Primarily terrestrial, some are secondarily aquatic in.
  • Two pairs of pentadactyl limbs.
  • Body covered by an exoskeleton of epidermal hair, feathers or scales.
  • Lungs are main respiratory organs. Amphibian may respire by gills, skin or lungs.
  • 3 or 4 chambered heart present.
  • They are divided into 4 classes: Amphibia, Reptilia, Aves and Mammalia

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