Today in class, we dissected an annelid (earthworm). We started by cutting the top dorsal side across the body. We later looked at all of the structures of the worm and made observations about its eating habits, how its circulatory system works, and where it's brain is. We mostly studied the digestive system: starting with the mouth, going along to the pharynx, and continues on. The crop and gizzard came next, leading onto the intestine (which was filled with dirt), and ending at the anus. Worms have a much simpler digestive system than that of a human's.
Ecology
Earthworms are divided into three subgroups. Compost dwellers, top soil dwellers, and deep soil dwellers. They are derivers, or decomposers. Populations of worms depend on the composition of the soil. Earthworms are the bottom of most food chains, and are preyed upon by many small animals. They contain many small parasites. Nitrogen rich fertilizers are acidic to earthworms, and kill them. To increase the population, the use of chemicals should be stopped.
Ecology
Earthworms are divided into three subgroups. Compost dwellers, top soil dwellers, and deep soil dwellers. They are derivers, or decomposers. Populations of worms depend on the composition of the soil. Earthworms are the bottom of most food chains, and are preyed upon by many small animals. They contain many small parasites. Nitrogen rich fertilizers are acidic to earthworms, and kill them. To increase the population, the use of chemicals should be stopped.