Naidinae
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| Ehrenberg , 1828 |
The Naidinae are annelids (Annelida). They form a subfamily in the Naididae family from the order of the little bristle (Oligochaeta). They are about 2–25 mm long, transparent aquatic worms, with larger forms (over about 10 mm) mostly being animal chains.
Traditionally, this subfamily was also treated as a separate family, sometimes even divided into two families, "Chaetogastridae" (with the genus Chaetogaster ) and "Naididae" (other genera). More recently, they have generally been seen as a subfamily of the Tubifex relatives formerly known as Tubificidae . Finally, after the Naidinae were incorporated, the Tubificidae were renamed Naididae because of the priority rule (the Naidinae were already described in 1828, the Tubificinae not until 1876).
biology
Most species live in fresh water, some in the littoral area . Some species can occur in large numbers, which is why, despite their small size, some of them were scientifically described as early as the 18th century (e.g. Stylaria lacustris Linnaeus 1767 and Nais elinguis Müller 1774).
They feed on all kinds of small organisms (algae, rotifers , small water fleas , etc.), whereby the ways in which they are absorbed are very different. Nais and Stylaria species turn out the floor and ceiling of their pharynx and press them against the surface of leaves, plant stems or the stone substrate. When you turn it back, the algae or other small organisms sticking to it are rolled into your mouth as if between two rollers. Ripistes species catch floating small organisms or detritus, which they collect by swaying long bundles of bristles. Chaetogaster species, in turn, live predatory by sucking in small organisms (single-celled and small multicellular cells); one subspecies ( Chaetogaster limnaei vaghini ) feeds endoparasitic.
Some species have simple eyes, which is unusual for the oligochaeta .
Mode of reproduction and animal chains
The Naidinae are characterized by a multiple asexual reproduction . Characteristic is the formation of two or more animals in the form of animal chains, which arise in the manner of a sprout . By dividing these animal chains (mostly as paratomy, developed by Allonais and some Dero species as architomy), new individuals can emerge in an asexual way, which genetically represent an identical image of the mother animal. However, in between (especially in late summer / autumn) normal bisexual reproduction often occurs.
Systematic affiliation
Although their genitals are in segments IV and V, they are placed in a common group with the Tubificinae and other subfamilies, in which the genitals are otherwise mostly in other segments. However, doubts remain about the definitive affiliation, since according to molecular genetic findings (16S rDNA and 18S rDNA) the grouping within the Naididae family, formerly called Tubificidae, does not form a natural monophyletic unit.
Systematic subdivision
Traditionally, the group has been divided into two subgroups, one subgroup being the Naidinae in the narrower sense, the other just including the genus Chaetogaster . The latter is characterized u. a. characterized in that it has only 2 bundles of bristles per segment, while the other genera have 4 bundles of bristles per segment.
The Naidinae comprise about 22 genera with over 100 species, including the following:
- Amphichaeta leydigi Tauber 1879, 1.5–4 mm long species; This genus, consisting of three species, evidently represents the transition between the genus Chaetogaster and the other Naidinae.
- Chaetogaster limnaei Baer 1827, an approx. 2–5 mm long species that lives either on or in freshwater mollusks (subspecies Ch. L. Limnaei and Ch. L. Vaghini ). The species Chaetogaster diaphanus Gruithuisen 1828, which occurs in fresh and brackish water, is strikingly large at up to 25 mm.- For more information on these "belly bristle worms" cf. under Chaetogaster .
- Nais elinguis Müller 1774, an approx. 10 mm long common species from freshwater. In addition, another 12 species of this genus have been described in Europe. Many but not all species of the genus Nais have eye spots.
- Ripistes parasita Schmidt 1847, a species approx. 4.5 mm long living in a tube. to VIII. segment carries greatly elongated bundles of bristles, which are associated with the acquisition of food. With eye spots. The only species of this genus in Europe.
- Pristina longiseta Ehrenberg 1828, German "Schnauzenwürmchen", approx. 2–5 mm long, with a snout-shaped extension of the head area. Occurrence of a. in boggy waters. A total of 16 species of this genus have been described in Europe. This genus is the most original in comparison to the other genres.
- Stylaria lacustris (Linnaeus 1767), German "Teichschlänglein" or "Teichschlänglein", a common and very transparent species of approx. 10-16 mm in length, which can be easily recognized by a conspicuously long, unpaired tentacle on the front and eye spots. It lives in the plant belt of calm waters (e.g. on the water cockfoot or the waterweed ) and feeds primarily on algae. They can multiply en masse on algae-grown aquarium walls. There is also a second species, Stylaria fossularis Leidy 1852.
Individual evidence
- ^ W. Westheide: Clitellata, belt worms. In: W. Westheide & R. Rieger: Special Zoology, Part 1: Protozoa and Invertebrates, 2nd Edition, Elsevier Spectrum, Munich 2007
- ↑ C. Erséus, T. Prestegaard, M. Källersjö: Phylogenetic analysis of Tubificidae (Annelida, Clitellata) based on 18S rDNA sequences. Mol. Phyl. Evol., 15, pp. 381-389, 2000
- ↑ E. Sjölin, C. Erséus, M. Källersjö: Phylogeny of Tubificidae (Annelida, Clitellata) based on mitochondrial and nuclear sequence data. Mol. Phyl. Evol., 35, pp. 431-441, 2006
- ↑ Bely, AE, Wray, GA (2003): Molecular phylogeny of naidid worms (Annelida: Clitellata) based on cytochrome oxidase I. Mol. Phyl. Evol. 2004: 50-63.
- ^ Streit, B. (1978): A note on the nutrition of Stylaria lacustris (Oligochaeta: Naididae). Hydrobiologia 61: 273-276.