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Class Oligochaeta

(Aquatic worms)

Soil & Water Conservation Society of Metro Halifax (SWCSMH)

[aquatic worms.jpg]


Updated: October 09, 2013      Freshwater Benthic Ecology and Aquatic Entomology Homepage


Contents:



Introduction

Oligochaetes are common in most freshwater habitats, but they are often ignored by freshwater biologists because they are thought to be extraordinarily difficult to identify. The extensive taxonomic work done since 1960 by Brinkhurst and others, however, has enabled routine identification of most of our freshwater oligochaetes from simple whole mounts. Some aquatic worms closely resemble terrestrial earthworms while others can be much narrower or thread-like. Many aquatic worms can tolerate low dissolved oxygen and may be found in large numbers in organically polluted habitats.

Aquatic worms can be distinguished by:

Four families in the orders Tubificida and Lumbriculida are common in freshwater in northeastern North America: the Tubificidae, Naididae, Lumbriculidae, and Enchytraeidae. In addition, freshwater biologists sometimes encounter lumbricine oligochaetes (order Lumbricina; the familiar earthworms), haplotaxid oligochaetes (order Haplotaxida; rare inhabitants of groundwater), Aeolosoma (class Aphanoneura; small worms once classified with the oligochaetes), and Manayunkia speciosa (class Polychaeta) in waters of northeastern North America.


Indicator value

Of the freshwater annelids, the oligochaetes display the greatest diversity and have the greatest indicator value. The two families, Naididae and Tubificidae form 80 to 100% of the annelid communities in the benthos of most streams and lakes at all trophic levels (Mackie, 2001).

Oligochaetes are common in most freshwater habitats, but they are often ignored by freshwater biologists because they are thought to be extraordinarily difficult to identify. The extensive taxonomic work done since 1960 by Brinkhurst and others, however, has enabled routine identification of most of our freshwater oligochaetes from simple whole mounts. Some aquatic worms closely resemble terrestrial earthworms while others can be much narrower or thread-like (Peckarsky et al, 1990).

The tubificids are gatherers, feeding on detritus in the sediments. They are the only worms present in the deepest regions of lakes and are represented by several indicator species. (Mackie, G.L. 1998. Applied Aquatic Ecosystem Concepts. University of Guelph Custom Coursepack. 12 chapters.).



References and web URLs:




Freshwater Benthic Ecology and Aquatic Entomology Homepage                     Soil & Water Conservation Society of Metro Halifax (SWCSMH) Master Homepage


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