The Canadian Nightcrawler (Lumbricus terrestris) is a large, common earthworm vital for soil health. Native to Europe, this species was widely introduced across North America. It is an anecic earthworm, creating deep, permanent vertical burrows in the soil. Its activity moves organic matter and aerates the ground, influencing soil structure and nutrient content, functioning as a detritivore that feeds on dead organic material.
Natural Diet and Habitat Consumption
The natural diet of the Canadian Nightcrawler consists primarily of detritus, which is decaying organic matter found on the soil surface. This includes dead leaves, plant residues, and dead roots in the upper soil layers. The nightcrawler comes up from its vertical burrow at night to forage, pulling surface materials down into its tunnel to consume them safely.
Worms graze on the coating of microorganisms, such as bacteria and fungi, that are actively breaking down the plant material, rather than eating the leaf matter itself. Nightcrawlers favor leaves high in calcium and nitrogen, such as those from basswood, ash, and sugar maple trees. They consume less palatable options, like oak leaves, only if higher-quality food is unavailable. They also ingest soil micro-organisms, dead insects, and animal feces.
The Digestive Mechanics of Earthworms
Digestion begins when the earthworm ingests soil and organic matter through its mouth. The food passes through the esophagus, where calciferous glands release calcium carbonate to neutralize soil acidity and regulate calcium levels. It then enters the crop for temporary storage. After storage, the food moves into the gizzard, a thick-walled, muscular organ. Since nightcrawlers lack teeth, the gizzard performs mechanical digestion, grinding the food into fine particles using strong muscle contractions and small mineral grains. This paste enters the intestine, where enzymes break down the organic matter and nutrients are absorbed. The undigested waste, rich in minerals and nutrients, is expelled as excrement called castings, which are deposited on the soil surface.
Feeding Canadian Nightcrawlers in Captivity
Maintaining Canadian Nightcrawlers in captivity requires providing a food source that mimics their natural diet. The worms get much of their nutrition from the bacteria within their bedding, which is commonly moist, chemical-free topsoil. Keepers can supplement the bedding with appropriate food materials placed directly on or just under the surface. Suitable food supplements include:
- Vegetable scraps
- Used coffee grounds
- Cornmeal
- Commercial worm feed
Avoid overfeeding, as uneaten food can decompose and create an anaerobic environment harmful to the worms. Exclude acidic foods like citrus fruits, oils, and meats, which create unsuitable bedding conditions. Regularly refreshing the bedding ensures a continuous supply of nutrient-rich, microbially active material.