Subphylum - Vertebrata

• Body divided into head, neck, trunk and tail. Some notable exceptions are there : Fishes lack the neck, amphibians lack both the neck and tail (exceptions are there).
• Have two pairs of appendages, which are in the form of fins in the fish and limbs in other vertebrates.
• Certain forms have secondarily lost one pair or both the pair of appendages.
• Have integument basically of two parts: an outer epidermis of stratified epithelium derived from the ectoderm and an inner dermis of connective tissue derived from the mesoderm.
• Endoskeleton is formed of cartilage or of cartilage and bone.
• Have a large coelom that contains viscera suspended by mesentries. It is divided into a pericardial sac and a general body cavity. Mammals possess a separate thoracic cavity also.
• The complete digestive tract of vertebrates is ventral to the nerve cord, and gives rise to digestive glands: pancreas and liver.
• In lower vertebrates respiratory organs are paired gills, whereas in land forms lungs are present.
• Closed circulatory system; heart 2, 3 or 4 chambered; lymphatic system present; erythrocytes and haemoglobin are present.

Notochord is only present in the embryonic stage, it is replaced by vertebral column in adult forms.

A pair of kidneys are present for excretion.

Endocrine glands are well developed.

Unisexual and have single pair of gonads.