Aeolosoma (Annelida) Videos

These transparent microannelids inhabit soils and decaying material in stagnant water, using cilia to move about. Like other annelids, Aeolosoma has a segmented body (roundworms and flatworms aren't segmented), generally consisting of about 17 segments. All but the first segment, after the head, bear sets of bristle-like structures called setae or chaetae.

The mouth is fringed with constantly moving cilia that create a vacuum cleaner effect, whisking up microscopic plants and organisms. The worms range in size from 1-2 millimeters, but often occur in long chains of immature worms, called zooids, up to 10 millimeters. These chains are produced by asexual budding, the means by which Aeolosoma reproduces.

These aquatic worms belong to the family Aeolosomatidae, which was recently put in its own class, Aphanoneura, along with the class Potamodrilidae. Some biologists, however, still classify this tiny worm in the class Oligochaeta, the same class to which the common earthworm belongs.

Currently, more than 830 species of annelids representing 27 families,12 orders, and five classes (Oligochaeta, Aphanoneura, Branchiobdellae, Acanthobdellae, and Hirudinea) are recognized as occurring in the U.S. and Canada; these include both native and introduced species.