Global Earth Worming

by Edward Cen Period 4 Mrs. Guzman

Objectives

Students will be learning about the external and internal anatomy of an earthworm. Students will focus on the organs, structures, and functions of the digestive system. Students will also understand the ecological role of the earthworm.

Background Information

Earthworm are Lumbricus terrestris and are annelids, or segmented worms under the kingdom Animalia. They are invertebrates. Earthworms prefer dark, damp soil as they regulate their respiration/water intake through the soil. Earthworms have many predators such as snakes, birds, rodents, and even many insects and are mainly decomposers, feeding on soil and nutrients in the soil. They reproduce with sperm ducts and oviducts. An earthworm has both male and female reproductive organs.


The earthworm also has setae, little hair on the outside of the worm to help it move in the soil. Also, to help preserve water, earthworms have adapted to become extremely sensitive to light so they will only come out when it is dark outside.

Taxonomy

  • Kingdom: Animalia
  • Phylum: Annelida
  • Class: Clitellata
  • Subclass: Oligochaeta
  • Order: Opisthopora
  • Family: Lumbricidae
  • Genus: Lumbricus
  • Species: Terrestris
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Earthworm Food Web

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Digestive System

The adult earthworm digestive system consists of the mouth cavity and followed by the pharnyx, where enzymes and mucus are added to aid in the passing of the food and soil through the esophagus. Next, the esophagus leads to the crop, which is a thin sack which holds soil before it moves onto the thick gizzard that grinds down the food so it can be absorbed by the intestines. Then follows the long track of intestines as it passes through the worm and nutrients are absorbed. Finally, the undigested food and soil leaves through the anus of the earthworm. The digestive system is controlled by the simple brain near the pharynx and the nutrients absorbed by the intestines is pumped by the lateral hearts of the circulatory system to spread nutrients around the worm.

Human Impact

Earthworms help human because they add nutrient and loosen up soil for humans. They are a key decomposer for most ecosystems and help recycle the soil to renew its nutrients. They also have a positive effect on bacteria and fungi in soil which makes plants growing in the soil more active.
Top Ten Secrets - #10 Earthworms, A Garden's Best Friend

Do you think you know your earthworm? Test Yourself!