Did You Know??? A segment is one of the small divisions on the surface of the worm The average earthworm has about 100 segments. Segmented worms have a ONE WAY digestive system Annelinds blood moves through a “closed” circulatory system. Which means blood is confined to blood vessels Earthworm need to remain moist at all times because they absorb oxygen through their skin.
Phylum Annelida (segmented worms) The Facts … Body symmetry- Bilateral Reproduction- Sexual Movement- muscular contraction Food- one-way digestive system – Scavengers
Why are Annelids good for our soil? 1. Break down organic matter 2. Make tunnels which help with aeration and drainage 3. Circulate nutrients in soil
Describe how each of these features help earthworms move through the dirt. 1Bristles- “setae” small hairs on the skin of worms, which helps them crawl through the dirt. 2Mucus – outer covering of slime helps them slide through the dirt and absorb oxygen.
Miss. Styer’s Example Procedure: 1. Set up tray at lab station. 2. Place dry paper towel on one half of the tray. 3. Wet a paper towel from the sink and on the opposite half of the tray. 4. Get earthworm. 5. Place earthworm on the center line between the wet and the dry paper towel. 6. Wait 3-5 min. 7. Record the earthworm’s movements in observation table. 8. Repeat steps 5 -7 at least two times.