Classification of animals helps us to understand how all living organisms are related to each other. The system of animal classification was developed by Swedish botanist Carolus (Carl) Linnaeus in the 1700s.Animals are divided into two groups on the basis of presence and absence of the backbone into: 1: Vertebrates 2:Invertebrtes.
Vertebrates:
These are a subphylum of chordates that are characterized by the presence of a vertebral column or backbone. It encloses and protects the spinal cord. It includes animals such as fish, amphibians, reptiles, birds, and mammals. Different characteristics are given below.
- They are characterized by the presence of a vertebral column or backbone. It encloses and protects the spinal cord. The body have a closed circulatory system.
- They show bilateral symmetry.
- Vertebrates have an internal skeleton made of bone or cartilage, providing structural support and protection for internal organs.
- They are triploblastic, and coelomate with the organ-system level of organization.
- The notochord is present only in the larval tail, but in some, it is present throughout their life from head to tail region
Invertebrates:
Invertebrates are any animals that are not Chordates. Non-vertebrates or invertebrates are the animals that do not possess a vertebral column or backbone. It includes variety of animals such as porifera, arthropods, mollusca, annelids, cnidarians, etc. Different characteristics of invertebrates are given below.
- They lack a backbone or vertebral column.
- They show radial symmetry or bilateral symmetry depending on their evolution.
- They are cylindrical, triploblastic, coelomate, or pseudocoelomate animals.
- Respiration is either through gills, trachea or body surface.
- Mode of reproduction can be sexual or asexual.
- Fertilization is external, though internal fertilization also occurs in some species.
- Open type of circulatory system is present.
