Although initially it is believed that vertebrate animals were in a fresh aquatic environment, later they have been able to adapt to marine (salty) water and then to the terrestrial environment. That said, the first vertebrate animals were fish and as a distinctive characteristic they did not have a jaw. They lived between 500 and 600 million years ago. These were identified by having a skull, but not a vertebral column. Later, amphibians, reptiles, birds and mammals appeared.
Within this large group it is possible to differentiate five sub-groups.
Common characteristics for all vertebrate animals
Have bony or cartilaginous spines
The function of the spine is to protect the spinal cord. This spinal cord, in turn, is responsible for carrying nerve impulses to the nerves. In other words, the spinal cord allows the connection of the nervous system through impulses (connections) between neurons.
They are hot or cold blooded
The first vertebrate animals were cold-blooded. Later, warm-blooded mammals and birds evolved. This means that they regulate their own body temperature from the inside unlike cold-blooded animals that can only regulate their temperature with changes in the environment.
Your body can be very variable. Thus mammals have skin and in many cases hair; reptiles may or may not have shells, but they are covered in scales; fish also have scales; amphibians are characterized by wet skin and birds have a body covered with feathers.
Mammals have legs (although aquatic mammals like whales and dolphins have fins like fish). Many reptiles have developed legs, but others only crawl; birds have legs and wings, while fish have fins.
All vertebrate animals present sexual differences: female or male, although the difference is often subtle to the naked eye (as is the case with fish, for example). Regarding sexual reproduction, mammals and some types of fish are viviparous , that is, the offspring are born from the mother’s womb. The rest of the vertebrate animals have an oviparous reproduction , that is, they hatch from eggs.
Breathing and Habitat
All vertebrate animals have lung respiration except fish whose respiration is gill.
As for the habitat, this is highly variable since they are animals that have been able to adapt to different environmental circumstances. Thus mammals, reptiles and birds live on land, although aquatic mammals live in water, as do fish. Finally, amphibians can inhabit either land or water.
Likewise, the way of moving around is different in each case: mammals walk; reptiles also walk or can crawl (in the case of those without limbs); fish swim, birds fly, and amphibians can jump or swim as in the case of frogs that move both ways.
50 Examples of Vertebrate Animals