choanoflagellates

Choanoflagellates are tiny, single-celled organisms found in aquatic environments, considered the closest relatives to animals. They have a round or oval shape with a collar made of tiny projections surrounding a flagellum—a whip-like tail that creates water currents. This structure helps them feed by trapping bacteria and small particles. Despite their simple appearance, choanoflagellates share key features with the cells of animals, making them important for understanding how complex multicellular life evolved from single-celled ancestors. They play an essential role in aquatic ecosystems and are studied to learn about the origins of animals.