Wednesday, July 7, 2010

Worms

Supplies

Worms (in LA: Purfield's Pro Tackle 12512 Washington Blvd. Los Angeles, CA 90066
(310) 397-6171)

Concept: Hands on exploration with Earthworms. Use your sense of touch and sight to observe worm head and tail movement. Can you identify the head/tail? What is the small section on the worm that is different than the rest? Can they survive being split in two?

Extension: Compare these invertebrate (have no backbones) to other invertebrates.

Wormy Facts: Earthworms bodies are made up of ring-like segments called annuli. The segments are covered in setae(small bristles), which the worm uses to move and burrow. The worm's first segment contains its mouth. Earthworms breath through their skin. They also have a brain,5 hearts, and mouths. Worms eat a third of their body weight daily. The familiar-looking bulge seen near the first third of the earthworm’s body is clitellum. The clitellum is a series of segments that are swollen to form a saddlelike structure in the anterior portion of the oligochaete. The function of the clitellum is mucous secretion during copulation and cocoon formation after copulation. Lastly, contrary, to the common myth; if split in two, two will not grow.

Application to Real World: While burrowing worms consume soil and extract nutrients from decomposing organic matter (leaves and roots). Earthworms are crucial to soil health since they carry nutrients and minerals from below to the surface through their waste and their tunnels aerate (air/ventilate) the ground. Earthworms are a source of food for many animals (birds/rats/toads). They also are frequently used in residential composting and as bait in commercial and recreational fishing.