Spirostomatea

Spirostomatea is a class of marine annelids, commonly known as polychaetes, characterized by their distinctive spiral-shaped mouth and a reduced number of chaetae (bristles) on their body. This class is found in various marine environments, including the deep sea and coastal regions. Spirostomateans are typically small to medium-sized worms, ranging from a few millimeters to several centimeters in length.

The class Spirostomatea was first described by the German zoologist Karl Grobben in 1906. It is divided into two orders: Spirobranchidae and Eulepethidae. Spirobranchidae is the more diverse group, containing over 100 species, while Eulepethidae is less diverse, with only a few species.

Spirostomateans are known for their unique feeding behavior. They use their spiral-shaped mouth to filter-feed, capturing small particles of organic matter from the water. This feeding strategy is thought to be an adaptation to the low oxygen conditions found in some of their habitats.

The taxonomy of Spirostomatea is still a subject of ongoing research. Some species have been reclassified or redescribed in recent years, and new species continue to be discovered. Despite these changes, the class remains an important group of marine annelids, providing valuable insights into the evolution and diversity of polychaetes.