Night crawlers are a common type of earthworm found in gardens and often used for fishing. They frequently emerge after rain or during evening hours, and their presence often indicates healthy soil.
Understanding Night Crawlers
“Night crawler” is a common name applied to several large earthworm species, most notably Lumbricus terrestris, known as the Canadian nightcrawler. These worms are characterized by their considerable size, typically reaching lengths of 4 to 8 inches, though some can grow up to 10-14 inches long. Their bodies are reddish-brown, cylindrical, and segmented, with each segment featuring tiny hair-like bristles called setae that aid in movement. A distinct band, the clitellum, is visible on their bodies, which is involved in reproduction.
Other species also fall under the “nightcrawler” umbrella, such as the European nightcrawler (Eisenia hortensis) and the African nightcrawler (Eudrilus eugeniae). While sharing large size and burrowing habits, these species vary in their preferred living conditions and specific uses. European nightcrawlers are often used in composting due to their efficiency in breaking down organic matter. African nightcrawlers are known for their voracious appetites and rapid composting ability in warmer climates.
Their Nocturnal Habits and Habitat
Night crawlers primarily inhabit moist soil rich in organic matter, such as gardens, lawns, and forests. During the day, these worms reside in deep vertical burrows that can extend several feet underground. Sensitive to light and dry conditions, they stay beneath the surface to maintain moisture necessary for skin-based respiration. Earthworms absorb oxygen directly through their moist skin, making a damp environment crucial for their survival.
At night, or after significant rainfall, night crawlers emerge to the soil surface. This nocturnal activity allows them to avoid the drying effects of sunlight and higher daytime temperatures. They forage for decaying organic matter, such as fallen leaves and plant debris, pulling it back into their burrows to consume. Mating also occurs on the soil surface, where individuals exchange sperm before retreating back underground.
Ecological Impact and Practical Uses
Night crawlers maintain healthy soil ecosystems. Their burrowing activities create tunnels that improve soil structure. These channels allow for increased aeration, enabling oxygen to reach plant roots more effectively, and enhance water infiltration into the ground. The movement of night crawlers also helps to loosen compacted soil, which supports deeper root growth for plants.
Beyond physical soil changes, these earthworms contribute to nutrient cycling. As detritivores, night crawlers consume decaying plant material and other organic debris, breaking it down into nutrient-rich castings. These castings, essentially worm excrement, return essential nutrients like nitrogen, phosphorus, and potassium to the soil in a form readily available for plants. This process accelerates decomposition and enriches the soil, fostering a robust microbial community.
Night crawlers also have practical applications for humans, most notably as fishing bait. Their large size, lively movements, and ability to survive underwater make them attractive to various freshwater fish species. Beyond angling, certain nightcrawler species, particularly European and African varieties, are widely used in vermicomposting. They efficiently convert kitchen scraps and other organic waste into valuable compost, reducing landfill waste and providing a nutrient-dense soil amendment for gardening.