The Naididae (including the former family Tubificidae) are a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

clitellate The Clitellata are a class of annelid worms, characterized by having a clitellum – the 'collar' that forms a reproductive cocoon during part of their life cycles. The clitellates comprise around 8,000 species. Unlike the class of Polychaeta, ...

oligochaete Oligochaeta () is a subclass of soft-bodied animals in the phylum Annelida, which is made up of many types of aquatic and terrestrial worms, including all of the various earthworms. Specifically, oligochaetes comprise the terrestrial megadril ...

worm Worms are many different distantly related bilateria, bilateral animals that typically have a long cylindrical tube-like body, no limb (anatomy), limbs, and usually no eyes. Worms vary in size from microscopic to over in length for marine ...

s like the sludge worm, ''

Tubifex tubifex ''Tubifex tubifex'', also called the sludge worm, sewage worm, or simply tubifex worm, is a species of tubificid segmented worm which inhabits the sediments of lakes and rivers on several continents. ''Tubifex'' likely includes several species ...

''. They are key components of the

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

communities of many

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

and marine

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

s. In freshwater aquaria they may be referred to as detritus worms.

Description

These worms can vary in size, from centimeters to millimeters, depending on the subfamily. They are all

hermaphroditic A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

and lack a larval stage.

Taxonomy

Analysis of

18S rDNA 18S ribosomal RNA (abbreviated 18S rRNA) is a part of the ribosomal RNA in eukaryotes. It is a component of the Eukaryotic small ribosomal subunit (40S) and the cytosolic homologue of both the 12S rRNA in mitochondria and the 16S rRNA in plastid ...

sequences revealed that the traditional family Tubificidae is not

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

, with the traditionally circumscribed Naididae nested within tubificid taxa. To avoid

paraphyly Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

the naidid and tubificid taxa were included in a combined family, which took the name Naididae because it has priority under ''

International Code of Zoological Nomenclature The International Code of Zoological Nomenclature (ICZN) is a widely accepted Convention (norm), convention in zoology that rules the formal scientific name, scientific naming of organisms treated as animals. It is also informally known as the I ...

'' rules as the

senior synonym In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently. ...

of Tubificidae. A proposal to the

International Commission on Zoological Nomenclature The International Commission on Zoological Nomenclature (ICZN) is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 26 commissioners from 20 countries. Orga ...

to suppress Naididae, because the "tubificids" are the more well-known group of the two, was rejected. The family Naididae is divided into six subfamilies, arranged here in the presumed

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

sequence: *

Tubificinae Tubificinae is a subfamily of annelids belonging to the family Naididae. The following genera are assigned to Tubificinae: * '' Baikalodrilus'' Holmquist, 1978 * '' Baltidrilus'' Timm, 2013 * '' Christerius'' Holmquist, 1985 * '' Clitellio'' ...

Eisen, 1879, containing (among others) the genus ''

Tubifex ''Tubifex'' is a cosmopolitan genus of tubificid annelids that inhabits the sediments of lakes, rivers and occasionally sewer lines. At least 13 species of ''Tubifex'' have been identified, with the exact number not certain, as the species a ...

'' *

Naidinae ''Naidinae'' is a subfamily of annelids belonging to the family Naididae. According to the World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and compre ...

Ehrenberg, 1828 * Telmatodrilinae Eisen, 1879 *

Limnodriloidinae Limnodriloidinae is a subfamily of clitellate oligochaete worms. Species The following genera are currently recognized within Limnodriloidinae: * ''Doliodrilus'' Erséus, 1984 * ''Limnodriloides'' Pierantoni, 1903 * ''Parakaketio'' Erséus, 19 ...

Erséus, 1982 *

Phallodrilinae Phallodrilinae is a subfamily of clitellate oligochaete worm Worms are many different distantly related bilateria, bilateral animals that typically have a long cylindrical tube-like body, no limb (anatomy), limbs, and usually no eyes. W ...

Brinkhurst, 1971 * Pristininae Lastočkin, 1921, often included in Naidinae *

Rhyacodrilinae Rhyacodrilinae is a subfamily of clitellate oligochaete worms in the family Naididae. Species The World Register of Marine Species recognizes the following genera in the subfamily Rhyacodrilinae: * ''Ainudrilus'' Finogenova, 1982 * ''Bothrio ...

Hrabě, 1963

Presence in aquariums

In an

aquarium An aquarium (: aquariums or aquaria) is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. fishkeeping, Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aquati ...

, numbers of naididae can increase rapidly. When their population becomes high, the worms migrate toward the surface of the water for access to higher concentrations of oxygen. Although detritus worms may not cause harm to aquarium fish, their appearance is an indication of poor water quality mainly due to overfeeding and lack of good water sanitation. Improvement of water quality, filtration, gravel cleaning, and the reduction of feeding, may be performed to bring detritus worm population back to normal. Detritus worms feed on excess food and waste, thereby contributing to the ecosystem of an aquarium.

Gallery

File:Tubifex02.jpg,

in sediment File:Naididae.jpg, Naididae in sediment - subject from Muddy River, Boston File:Naididae swimming 2.jpg, Naididae swimming - subject from Muddy River, Boston File:Naididae swimming.jpg, Naididae swimming - subject from Muddy River, Boston

References

Annelid families Taxa named by Christian Gottfried Ehrenberg {{annelid-stub