Main Characteristics

  • Notochord present at some stage of life, in most cases replaced by backbone.
  • Dorsal tubular nerve cord.
  • Gill slits present at some stage of life (larva or adult).
  • Body with a head and trunk and two pairs of appendages.


  1. Subphylum Urochordata
  2. Subphylum Cephalochordata
  3. Subphylum Vertebrata

The subphylum vertebrata has two super classes - Agnatha (jawless vertebrate) and Gnathostomata (jawed vertebrata).


Class 1: Chondrichthyes

Chondro means cartilage and ichtyes means fish

Class 2: Osteichthyes

Os means bone and ichthyes means fish

Class 3: Amphibia

Amphi means double or both and bios means life. It refers to life on land as well as in water

Class 4: Class Reptilia

Reptere means to crawl. They are four-legged or legless crawling animals whose body is covered by scales. They lay eggs on land.

Class 5: Aves

Avis means Bird

Class 6: Mammalia

Mamma means breast

Birds and mammals have a constant body temperature. The are termed homoiothermal.