Lambricus

Identifying Features

Earthworms are around 8 inches in length and a brownish purple color. Their skin is moist and smooth, and their bodies are segmented.

Habitat & Range

All of the earthworms that now live in New York State, and across much of North America, were brought here following the arrival of Europeans just a few centuries ago. Native earthworms were present, but were exterminated by the glaciers which repeatedly scoured northern North America over the past 2-3 million years. The re-colonization of previously glaciated areas by earthworm species was apparentlly slow - they advanced an estimated 20 feet per year without human assistance, and native species never made it back to New York. European settlers then introduced new species of earthworms, probably initially unintentionally.

It is likely that earthworm introductions accelerated during the twentieth century due to human activity that aided transport.The effects of these introduced worms on native forests have only come to the attention of scientists in the past 30 years.

This includes:

1. Reducing the thickness of leaf litter, which trees and plants use as a rooting medium,

2. Accelerating the decomposition of plant litter, which can increase the rate of recycling of essential nutrients like nitrogen and phosphorus, but may also result in nutrient losses from the soil in run-off water,

3. By reducing leaf litter, the underlying mineral soil is exposed and has a higher likelihood of erosion,

4. Increasing the decay of organic matter in the soil, releasing substantial amounts of carbon dioxide to the atmosphere and reducing the amount of carbon sequestered in the soil,

5. Earthworms alter the soil pH by mixing lower layers of higher pH soil with more acidic soils near the surface and stressing plants,

6. They consume as much as 15% of the fine feeder roots in the soil,

7. They create burrows that cause water to drain and the soil to dry out more quickly.

Behavior

Earthworm species have different lifestyles, some feed entirely in leaf litter, some only deep underground.

Life Cycle

Earthworms have hermaphroditic mating, and will lay small cocoons that hatch after 2-4 weeks.

Featured image by James Dake