Have an active form of locomotor muscles and have limbs in pairs.
Heart grow well, with the ventricles (booth space) and atrium (porch), there are bears two, three or four.
The digestive system is perfect, extending from the mouth to the anus at the base of the spine. Generally have teeth, tongue, and two pairs of jaws, except on Agnatha (Cyclostomata). There are liver and pancreas.
Gills in vertebrates that live in the water, and lung in vertebrates that live on land.
Has a pair of kidneys. Some are having bladder.
The senses and the nervous system
Have a central nervous system such as brain and spinal cord. Generally have a pair of eyes, ears, and have hormonal glands.
Reproductive pairs, except at Aves females only have one ovary left. Separate sex or hermaphrodite in larvae and as adults as animal Diesis (married two). External or internal fertilization. There are ovipar, vivipar, or ovovivipar.