What do annelids use to move

When they eat, they also take in soil and tiny pebbles. Earthworms take in nutrients from microorganisms in the material they ingest. They then excrete wastes in the form of casts. Casts are rich in nutrients like nitrogen, phosphorus, and potash. In addition to breaking down organic materials and adding nutrients to the soil, earthworms also help loosen the soil so air can circulate. This helps plants grow. It's all about efficiency. That's what helps you, your species, and your world survive.

If you are a parasite and you kill your host before you reproduce, you're out of luck. It's not efficient. You have an advantage when you are efficient. That advantage is what makes life easier for you. And, if you can pass that advantage on to your kids better eyes for finding food , so much the better.

Useful Reference Links. See the full list of biology topics at the site map! Current Page: Biology4Kids. They are paid advertisements and neither partners nor recommended web sites. They anchor their bodies with bristle-like structures on the outside of the segments. If all the material that has moved through earthworms were piled up on the surface of the globe, the heap would rise 30 miles, more than five times the height of Mt.

Skip to main content. These help provide traction as the animal moves through the soil. Find the dorsal blood vessel. This structure should be visible through the body wall and will appear slightly darker than the rest of the body. It extends the length of the animal. With a scalpel, make a shallow cut along the dorsal surface beginning at a point approximately half way between the clitellum see photograph below and the posterior end and ending at the anterior end.

Try to avoid cutting the dorsal blood vessel by keeping your cut to one side of the vessel. Try to cut only the body wall but not the internal structures. The septa between each segment will prevent you from spreading the walls open to view the interior structures.

Use a needle or scalpel to carefully cut the septa while spreading the body open. Pins can be used to hold the body open. Find the structures shown in the photographs below. Be sure that you understand the function of each of these structures.

Figure 3. Left: The anterior end of the worm. Middle: The brain. Right: The mid-section. Use a needle to cut the septa in the region of the intestine and roll it aside to expose the nerve cord underneath.

Examine a labeled earthworm composite.