Guzman - PAP Bio - 7. Juan Torres.


Students will learn a sufficient amount of information about the external and internal form of an earthworm, and about its digestive system.

The Earthworm

The earthworm, also known as by its scientific name 'Lumbricina,' is a tube-shaped organism that is known to live in soil and feed on dead organic matter. The earthworm belongs to the kingdom animalia, the phylum annelida, and the class oligochaeta.

Earthworms are heraphrodites, meaning they carry both male and female organs. They are also both invertebrates, but they lack a skeleton. Earthworms are also commonly referred to as "night crawlers" , "dew worm" , "rain worm" , and "angle worm." An earthworm's niche is to improve the soil by means of natural aeration. Earthworms also break down organic waste and excrete nitrogen-rich wastes that is beneficial to the soil.

An earthworm has many adaptations:

  • Each segmented portion of an earthworm's body contains a number of bristly hairs called setae, which improves the earthworm's grip as it moves through the soil.
  • An earthworm has a streamlined body that enables it to live in narrow burrows and move in the soil effortlessly.
  • In order to reach food, an earthworm pushes its pharynx out of its mouth to get the food.
  • When the soil is too hot or too dry, an earthworm goes through aestivation, a process that helps the earthworm adapt to sudden environmental changes.

The Digestive System

There are many organs in an earthworm's digestive system, such as the gizzard, the crop, the esophagus, pharynx, the mouth, the stomach, and the intestines. The digestive system plays a major role in enabling an earthworm to swallow and digest food.

Interesting Facts!

  1. There are about 6,000 species of earthworms in the world.
  2. Earthworms breath through their skin, as they lack lungs.
  3. Each earthworm is both male and male, producing both sperm and eggs.
  4. Earthworms can grow from 1/2 of an inch to 10 feet.
  5. An earthworm's digestive system runs through its whole body.
  6. Baby earthworms emerge from tiny eggs but are fully formed.

The area highlighted is where earthworms are found in the world.

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