Earthworms

This week in the homeschool Biology class I teach we talked about earthworms. Earthworms are a valuable member of our ecosystem and a great garden help. You can always tell healthy soil by how many earthworms you turn over in a shovel scoop. Earthworms can be called nature's little "rototillers". Their feeding habits enrich the soil and their movements aerate the soil. Here is a basic description of how these things work.

Earthworms suck in soil through their pharynx (mouth). After the soil is sucked into the digestive track, it then is stored temporarily in the crop. From their it travels to the gizzard where it is ground up into smaller bits. Next, it goes into the intestinal track where digestive enzymes are added and the organic materials it needs for its nutrition are absorbed into the body. Like our digestive system, waste products then continue through the intestinal system and are excreted out the anus. Yes, worms poop and that is part of our soil make-up. They also have small organs which act like kidneys. They take the waste products from the food being digested and excrete it through the skin (yes, worm pee). This process helps the soil break down matter into a substance that plants can then use for their energy production (photosynthesis or biosynthesis).

By "eating" soil, worms loosen the soil in front of them which makes it easier to dig forward in their movement. It also loosens the soil's particles which allow it to absorb water and oxygen that plants need. Worms don't just tunnel in one layer of the soil. They are always moving up and down between layers. This mixes the nutrient rich soil (where plants and other things are decaying) at the top with the mineral rich soil deeper down. This makes an ideal mixture for plants to continue to thrive. Without earthworms in the ecosystem, soil would no longer be fertile and able to support plant life.

As you can see, earthworms are a valuable member of your healthy lawn, compost, flower beds and garden. Without them, soil fertility soon disappears. They are a very important gardening friend.