Choanoflagellates

Choanoflagellates are a group of protozoa that belong to the phylum Choanophyta. They are characterized by the presence of a flagellum surrounded by a collar of microvilli, which they use to capture food particles from the surrounding water.

Choanoflagellates are typically found in aquatic environments, such as oceans and freshwater bodies. They range in size from 5 to 200 micrometers in length and are usually cylindrical or oval in shape. The flagellum is usually a long, whip-like structure that extends from one end of the cell, while the collar is a ring-shaped structure that surrounds the flagellum and contains many tiny projections called microvilli.

These microvilli are responsible for capturing food particles, which are drawn into the cell by the flagellum's motion. The food particles are then engulfed by the cell membrane and engulfed by a process known as endocytosis. Choanoflagellates play an important role in aquatic ecosystems as both predators and prey, and are also thought to have been one of the earliest multicellular life forms on Earth.

Choanoflagellates are thought to be a key player in the evolution of multicellularity, with some species being composed of multiple cells. They may have been an important stepping stone between single-celled and multicellular life, and thus have a significant place in the history of life on Earth. Despite their importance, choanoflagellates are still relatively understudied compared to other groups of protozoa, and much remains to be learned about their biology and ecology.