Earthworm Antics

Earthworm Dissection Pre-AP Biology April 8th 2014 - GUZMAN

Lumbricus terrestris

Earthworms are members of the order Megadrilacea and can be sorted into the suborders of Lumbricina and Moniligastrida. They belong to the kingdom Animalia under the phylum Annelida and class Oligochaeta. An earthworm is well-adapted to a life of burrowing through the soil; this can be shown through its streamlined shape, which helps it move through mud and dirt. They are known to increase soil fertility by playing a large role in the conversion of large pieces of organic matter into rich humus. Earthworms also maintain soil structure by creating passageways for drainage to occur.

Today's 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.

Taxonomy and Evolution

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Taxonomy

Categorization of a megadrile earthworm into one of its taxonomic families under suborders Lumbricina and Moniligastrida is based on such features as the makeup of the clitellum, the location and disposition of the sex features (pores, prostatic glands, etc.), number of gizzards, and body shape. Currently, over 6,000 species of terrestrial earthworms are named.

Human Impact

The Amazing World Of Earthworms In The UK - Springwatch - BBC Two
Earthworm have an extremely large impact on humans. Earthworms are key to enriching organic matter into rich humus, which gives nutrients to the soil and allows for a more sustainable environment to grow crops in. Earthworms can also be harmful, however. Invasive earthworms have been known to be a menace. For example, in the northern American forests, invasive species of earthworms have been knowne to mix plant scraps with leaves and soil, proving disastrous for the complex network of the ecosystem of the forest, and affecting all aspects of it - the soil, water, plants and animals.

Ecology

Earthworm Dissection LabCast

Earthworm Dissection Lab

Digestive System of the Earthworm

An Earthworm’s digestive system is one of the most important features of the worm. The food particles pass from the mouth to the pharynx where the food is lubricated by mucus secretions. This makes it easier to pass along to the esophagus. Next, the food is temporarily stored in the crop where they will get mixed together. From the crop, the mixture enters the gizzard, and from there, the intestine. Finally, at the end of the intestine, the digested particles are defecated through the anus.

Digestive System in Relation to Other Systems

The digestive system of the earthworm is integral to all other systems because it is used to provide energy for the earthworm for other purposes. For example, the earthworm can only move due to its digestive system, because it navigates soil by consuming the soil in front of it and moving forward.

Fun Facts

  • The largest earthworm recorded was found in Africa and was measured to be about 22 feet from tip to tail.
  • Even though worms don’t have eyes, they can sense light, especially at their anterior (front end). They move away from light and will become paralyzed if exposed to light for too long (approximately one hour).

Perform A Dissection Online!

This Project is By

Ajay Singh

Mrs. Guzman - PAP Bio - 4th