Animal Kingdom constitutes all animals. Amongst the five kingdoms, the largest kingdom is the animal kingdom. Animals are multicellular eukaryotes. However, like plants, they do not possess chlorophyll or a cell wall. Therefore, members of the animal kingdom exhibit a heterotrophic mode of nutrition.
Classification of Animal Kingdom
Animals are eukaryotic, multicellular, species belonging to the Kingdom Animalia. Every animal has its own unique characteristics. They obtain their energy either by feeding on plants or other animals. There are millions of species that have been identified, few share similar characteristics while others differ drastically.
- Protozoa: These are a different group of eukaryotic organisms which are unicellular having some similar characteristics to animals such as motility and predation. Protozoa take in food by the process of osmotrophy that is by engrossing the nutrients through the cell membranes or also they feed on phagocytosis, either by the process of engulfing the particles of the food with the help of pseudopodia.
- Bryozoans: They are filter feeders which sift food particles out of the water using a crown of tentacles lined with cilia and most of them dwell in humid waters, few in glacial waters, and some in marine trenches. Most of them are colonial and one genre is solitary. Zooids are individuals in bryozoans and they are not completely independent species. All colonies have auto zooids, which are accountable for feeding and excretion.
- Vertebrates: Vertebrates are animals possessing backbones. Some include jawed vertebrates and jawless fish. Ex: sharks, ray fish, and bony fish. A bony fish named clad also further falls into the class of amphibians, reptiles, mammals, and birds. Extant vertebrates vary in size beginning from the frog species named Paedophryne amanuensis to the blue whale. Amphibians are species that live in the land and move to water for breeding. Reptiles are covered by scutes. Mammals are terrestrial, aquatic, or aerial. Birds are covered with feathers and have streamlined avenues.
- Organ Level of Organization: Animal tissues comprising of similar capacity are classified into shaped organs. Every organ is definite for a particular capacity. For example Platyhelminthes.
- Tissue Level of Organization: Animal cells displaying the division of exercises among themselves.Cells performing the same function cooperate to form tissues.
- Organ Level of Organization: The organ framework level of organization is displayed in those organisms where organs define the shape of functional frameworks and each framework is with a distinct physiological capacity.
- Cellular Level of Organization: This organization consists of animals with cells that are formed as free cell lumps.