Annelida: Oligochaete Anatomy
Oligochaete Anatomy
Like the polychaetes, oligochaetes have bodies divided into segments. However, they lack parapodia and, with a few exceptions, have relatively few and inconspicuous setae. The setae are usually arranged in four bundles on each segment; those of aquatic forms are longer than those of land forms. The setae of an earthworm may be felt as a roughness if one rubs a finger along its side.
Oligochaetes are less varied in their external form than the polychaetes, but are much more numerous. As many as 4,000 oligochaetes have been counted in 1 square meter of lake bottom, and about 9,000 in 1 square meter of meadow soil. In almost all oligochaetes, the head is a simple cone-shaped structure without sensory appendages. Light is detected by photoreceptor cells in the skin, usually concentrated toward the front of the animal.
Sections in this article:
- Introduction
- Leech Reproduction
- Leech Predation and Digestion
- Leech Anatomy
- Class Hirudinea
- Oligochaete Reproduction
- Oligochaete Circulation and Respiration
- Oligochaete Digestion
- Oligochaete Anatomy
- Class Oligochaeta
- Archiannelida and Myzostomaria
- Polychaete Reproduction
- Polychaete Anatomy
- Sedentary Polychaetes
- Errant Polychaetes
- Class Polychaeta
- Reproduction
- The Nervous System
- Respiration
- Circulation
- Digestion
- The Body Wall
- Segmented Bodies
- Bibliography
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2024, Columbia University Press. All rights reserved.
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