They learn that worms affect the properties of their habitat, and the properties of soil affect the population of worms. This becomes the basis for developing a hypothesis and designing an investigation. Additional time is required for conducting the investigation, which will depend on the study design. Adaptable to Grades 4 - 8. Oxygen from the air passes directly through their moist skin, so dryness will kill them.
Worms have no eyes or ears, but they have cells that sense light and dark, and they sense vibration.
The latter is especially important for avoiding their chief predators, birds, moles and people. Worms eat organic matter such as leaves and grass, turning it into a rich compost. They pull organic matter from the surface and digest it in their burrows. In general, earthworms recycle their weight in organic waste every 2 days. Earthworms can regenerate or replace segments to a certain extent if they are injured.