👉 Pantostomata is a group of marine invertebrates that belong to the class Annelida, and are characterized by their specialized organ system known as the pannus. The pannus is composed of a central cavity surrounded by a series of small chambers called the ganglia. These chambers are filled with cells that produce a variety of proteins, hormones, enzymes, and other substances that play important roles in the organism's function. Pantostomata include many different species,