Kingdom Animalia

Animals are quite distinct from members of the other kingdoms. Unlike prokaryotes and protists, animals are multicellular. In fact, some of the largest animals have trillions of cells. Unlike plants, animals are heterotrophs.

Characteristics of the kingdom

1. Animals are multicellular eukaryotes with a high level of tissue differentiation and specialized body organs.
2. They have cells which have no cell walls.
3. They have no chlorophyll; therefore, they have heterotrophic nutrition. They cannot manufacture their own food and instead must ingest it and break it down metabolically for its energy content.
4. They can move about at some point in their life cycle – usually through the entire cycle – to search for food and mates and to avoid danger.
5. They are diploid, and their mode of reproduction is sexual, because each individual grows and changes from organs, it passes through various distinct stages of development.
6. They are radial or bilaterally symmetrical.
7. Some have diploblastic or triploblastic body plans.
8. Some have exoskeletons.
9. Some are pseudocoelomate (coelomates and acoelomates).

Classification of kingdom Animals

1. Phylum Platyhelminthes (e.g., Fasciola/Taenia)
2. Phylum Aschelminthes (Nematoda) e.g., Ascaris (roundworms)
3. Phylum Annelida e.g., earthworms
4. Phylum Arthropoda e.g., cockroach, locust, millipede
5. Phylum Chordata