Jordmaskar

Jordmaskar, commonly known as earthworms, are a group of segmented worms within phylum Annelida, class Clitellata, subclass Oligochaeta. They are primarily terrestrial and inhabit the upper layers of soil, leaf litter, and compost, though some species live in freshwater or marine environments. Most species are detritivores, feeding on decaying organic matter and soil organic material, which accelerates decomposition and enhances soil structure.

An earthworm's body is a long, cylindrical, segmented tube. Each segment bears tiny bristles called setae that aid movement. The body has a ventral nerve cord and a simple digestive system; respiration occurs mainly through moist skin. The clitellum, a thickened, glandular band near the anterior end of sexually mature individuals, secretes mucus during reproduction.

Earthworms move by alternating contractions of circular and longitudinal muscles, producing peristaltic waves that push the worm through soil. They create burrows, which improve soil aeration, drainage, and the mixing of organic matter with mineral soil. Castings, the worm’s digested material excreted as cast, are rich in nutrients and beneficial for plant growth.

Most earthworms are hermaphroditic, possessing both male and female reproductive organs. They typically mate with another individual, exchange sperm, and later form a cocoon around the clitellum in which eggs are fertilized and develop into juveniles.

Varieties range widely in size, color, and habitat preferences. The red wiggler (Eisenia fetida) is commonly used in composting and vermiculture. In ecosystems, earthworms are key contributors to soil fertility but can become problematic when introduced to non-native environments or exposed to pollutants.