Metazoans (/ˌmɛtəˈzoʊənz/) are a diverse group of multicellular organisms that include animals such as insects, fish, reptiles, and mammals. The word "Metazoans" is spelled with a "z" instead of an "s" because it is derived from the Greek word "meta," which means "beyond," and "zoon," which means "animal." In IPA phonetic transcription, the stress falls on the third syllable, with the "o" pronounced as a long "o" sound, and the "a" pronounced as a short "a" sound.
Metazoans, also known as metazoa, are a diverse group of multicellular organisms belonging to the kingdom Animalia. They represent a significant portion of the animal kingdom, encompassing a wide range of animal species, from simple to complex organisms. Metazoans are characterized by their distinct cellular organization and specialized tissues that perform specific functions within the body.
The defining feature of metazoans is their multicellularity, which means they are composed of multiple cells that work together to form different organ systems and carry out various vital functions. Unlike single-celled organisms, metazoans have differentiated cells organized into tissues, resulting in a higher level of anatomical complexity and physiological capabilities.
Metazoans can be found in diverse habitats, including terrestrial, freshwater, and marine environments, and they exhibit an incredible array of morphological adaptations to their respective niches. They range in size from microscopic organisms such as sponges and microscopic worms to large animals like elephants and whales.
Metazoans include a broad spectrum of animal groups, ranging from invertebrates like sponges, insects, mollusks, and crustaceans to vertebrates such as fish, reptiles, birds, and mammals, including humans. This diversity reflects their evolutionary success and ability to adapt to different ecological niches.
The study of metazoans is crucial in understanding the evolution and biology of animals, their classification, ecological roles, and their interactions with other organisms and the environment.
The word "Metazoans" is derived from two Greek roots: "meta" meaning "beyond" or "after" and "zōon" meaning "animal".
In Greek, "meta" often denotes a sense of change, transformation, or progression. "Zōon" specifically refers to animals. Therefore, the combination of these two roots in "Metazoans" signifies organisms that have progressed or developed beyond single-celled animals (protozoans) to form multicellular organisms, notably animals.