Nightcrawlers Gastronomical Tract

By: Ania Lewis ~ Ms. Vu - PAP Biology - Period 4th

Earthworm Digestive System

Objectives

  • We will explore the internal and external parts of an earthworm

  • We will cover the organs and other parts of the earthworm

  • We will learn the functions and locations of these organs

  • We will study the structure and functions of segmented worms

Background Information

  • The scientific name for an earthworm is Lumbricus terrestris

  • Live in warm, moist soil

  • Preyed on by birds, snakes, and beetles

  • Earthworms are decomposers and eat decaying matter in the ground

  • Found in gardens and other areas with soil, Earthworms act as decomposers and fertilize the soil and provide as a food source for birds, snakes, and beetles

  • Taxonomy:

      • Kingdom: Animalia

      • Phylum: Annelida

      • Class: Oligochaeta

      • Order: Megadrilacea

      • Family: Lumbricidae

      • Genus: Lumbricus

      • Species: Lumbricus terrestris


    Evolution:

      • Rise to surface of soil when it rains to mate

      • Tube-like shape helps to move easily through the soil.

      • Segments of an earthworm have setae, bristly hairs, to help it move through soil.

      • Earthworm uses pharynx to grasp its food. Pharynx pushes out of its mouth.

    Human Impact/ Influence:

      • Humans use earthworms to break down dead materials to re-fertilize soil

      • Earthworms are used for bait for fishing

Digestive System

Organs: pharynx, esophagus, crop, intestine, gizzard


Earthworms posses a full digestive tract running from the mouth to the anus. First, food enters the mouth and is passed on to the pharynx. In the pharynx, glands secrete mucous and enzymes to help pass the food down the esophagus. The crop, a thin- walled sac that holds soil before it is passed to the gizzard. the jub of the thick- walled gizzard grinds food up so that the nutrients can be absorbed as they travel through the intestine. Undigested food and any remaining parts are excreted from the body through the anus.


The esophagus is located under parts of the circulatory and reproductive systems.

A worms digestive system is extracellular which means that food is broken down into nutrients by enzymes.

Extra Information

  • Earthworms have male and female reproductive parts.
  • Intestinal deposits representing earthworm diggings are called custings.
  • Earthworms do not have a system for respiration, therefore, they must breathe using diffusion through moist skin.
  • The seminal receptacles receive and store sperm from other worms
  • The aortic arches are five pairs of enlarged tubes that function like hearts
  • The niphridia are pairs of excretory structures that function like kidneys
  • An earthworm has a closed circulatory system