Tubifex tubifex, also called the
sludge worm, or
sewage worm, is a
species of
tubificid segmented worm that inhabits the sediments of
lakes and
rivers on several continents.
T. tubifex probably includes several species, but distinguishing between them is difficult because the
reproductive organs, commonly used in species identification, are resorbed after mating, and because the external characteristics of the worm vary with changes in
salinity. These worms ingest sediments, selectively digest
bacteria, and absorb molecules through the body wall.
The worms can survive with little
oxygen by waving
hemoglobin rich tail-ends to exploit all available oxygen. They can also survive in areas heavily
polluted with organic matter that almost no other species can endure. By forming a protective cyst and lowering its
metabolic rate,
T. tubifex can survive drought and food shortage. Encystment may also function in the dispersal of the worm.
[edit] Uses
Ecologically, the worms are important as a source of food for
leeches,
crustaceans,
insects, and
fish.
Tubifex are sold as fish-food in both live and
freeze-dried, pelletised forms. While the worms are relatively easy to culture, they can take up to a month before they can be harvested. Although they are high in protein, they are not recommended for human consumption due to a high salt content.