The new system of animal classification is in practice now. All multicellular animals are included in Kingdom animals according to the five-kingdom classification system of Robert Whittaker. This classification system is based upon criteria like body organization, body symmetry, body cavity, germinal layers, segmentation, etc.
Criteria for New Systeme of Animal Classification :
1. Grades of Organization :
The body of animals is made up of cells. Many cells perform a different function in the body of multicellular animals.
a) Protoplasmic Grade Organization :
The body is made up of a single cell and all functions are performed by single-cell only in unicellular animals. Such body organization of unicellular animals is called Protoplasmic grade Organization.
b) Cellular Grade organization :
When tissues are not formed in multicellular animals, such body organization is called Cellular Grade Organization. For example, phylum-Porifera.
c) Cell Tissue Grade Organization :
When cells come together to form tissues. All the body functions are performed in animals with the help of tissues, such body organization is called Cell tissues grade organization.
d) Tissue Organ Grade Organizatiion :
Tissues are organized to form some organs but complete organ systems are not formed, this type of organization is called Tissue Organ Grade Organization.
e) Organ System Grade Organization:
Different organs are joined together to form an organ system that performs specific functions this type of organization is called Organ SystemGradeOrganization. e.i. crab, human, etc.
2) body symmetry:
If a body of the animal is cut through the imaginary axis of the body, the body may be divided into two equal halves or may not get two equal halves. This is depending on the property of animal bodies. Following are the kinds of body symmetry.
Asymmetrical body:
There is no such imaginary axis of the body through which we can get two equal halves is called Asymmetrical body as amoeba and paramecium and some sponges.
Radial symmetry :
If the body of any animal is cut through the imaginary axis of any plane of the body, gives two equal halves is called Radial Symmetry as starfish.
Bilateral symmetry:
There is only one such imaginary axis of the body through which we can get two equal halves as humans, insects, fishes, frogs, birds, etc.
3) germ layers
Germ layers are formed during the initial period of embryonic development and different tissues are formed in the body. Following are the kinds of Germ Layers.
Diploblastic germ layers:
Some animals have only two germ layers: Endoderm and Ectoderm.
Triploblastic germ layers:
Most of the animals have three germ layers as Mesoderm, Endoderm, Ectoderm.
4) Body cavity / Coelom:
The cavity between the body and internal organs is called Body Cavity or Salem.
The body cavity is formed from either mesoderm or gut during the initial period of their embryonic development in multicellular animals such animals are called Eucoelomate (animals with true body cavity).
The body cavity is absent in the case of some animals, such animals are called acoelomates.
Animals have body cavity but it is not formed by Eucoelomate and acoelomate, hence those animals are called Pseudocoelomates.
5) body segmentation:
If the body of animals is divided into small similar units then such body is called the segmented body and each small unit is called Segment.
Thus, we have Learning all the animals through the criteria above mentioned. I hope this blog is very helpful to you. For more updates follow us. Thank you.
