Metazoa

Metazoa is a biological group that includes all animals. The term is used to differentiate animal life from other forms of life, such as plants (Plantae) and fungi (Fungi). Metazoans are multicellular organisms that are typically characterized by their ability to move, their heterotrophic mode of nutrition, and their complex tissue structure.

Classification

Metazoa is a subkingdom within the kingdom Animalia. It includes all animals except for the most primitive ones, such as sponges (Porifera) and placozoans (Placozoa). The subkingdom is further divided into two branches: the Parazoa, which includes the aforementioned sponges and placozoans, and the Eumetazoa, which includes all other animals.

Characteristics

Metazoans are characterized by their multicellularity, heterotrophic mode of nutrition, and ability to move. They have complex tissue structures, with cells organized into tissues and organs. Most metazoans reproduce sexually, although some can also reproduce asexually.

Evolution

The evolution of metazoans is a topic of ongoing research. The earliest known metazoan fossils date back to the Ediacaran period, around 600 million years ago. However, molecular clock studies suggest that metazoans may have originated much earlier, possibly as far back as 1 billion years ago.

See also

• Animal
• Multicellular organism
• Eukaryote

References

Metazoa Resources
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