Earthworm Eager

Earthworm Dissection Virtual Lab by: Tina Liu Vu-PAP Bio-4

OBJECTIVES

The objective of this lab is to give each student an opportunity to observe the external and internal structure of the earthworm.

Lumbricus terrestris - The general information

How do we classify an earthworm? The earthworm is placed in Kingdom Animalia, Phylum Annelida, Class Oligochaeta, Subclass Haplotaxida, Order Megadrilacea, and suborders of Lumbricina and Moniligastrida, the general species of earthworms is terrestris.

Where do earthworms live? The general habitat of an earthworm is in the soil. However, depending on which species of earthworm, earthworms also live in decaying plant matter and manue, decaying logs, mud, aquatic and euryhaline habitats, and littoral habitats.


What adaptations do earthworms have that help them survive? Each segment on an earthworm’s body has setae, which are hairs that provide grip to help the earthworm move through the soil. An earthworm also has adapted to have a streamlined body with no antennae, fins, arms, or legs. This shape allows easy passage through narrow burrows underground through soil. The circular muscles around each body segment also work together to help the earthworm move. Many earthworms also secrete a mucus that helps them slide through the soil more easily.

Earthworms: Eat or Enemies?

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Evolutionary relationship of an earthworm (cladogram)

Earthworms are in the phylum annelida, so they are placed in the cladogram next to the arthropoda and onychophora.
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Earthworm Anatomy
Virtual Earthworm Dissection

Think you know the parts of an earthworm well? Test yourself on this virtual earthworm dissection!

Digestion System

Food enters the mouth and is followed by the pharynx, where enzymes and mucus aid the food to pass through the esophagus. The food is then stored in the crop until it can be emulsified in the gizzard with the aid of soil particles. Then follows the long track of intestines through the worm while the nutrients are continued to be absorbed. Finally, the undigested food and unnecessary nutrients leaves through the anus. The digestive system provides the necessary nutrients and energy so the body of the earthworm can continue functioning.

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Map of the native earthworms in the United States

Based on this diagram, we can tell the diagrams occupy more of the eastern United States and along the west coast.

FUN FACT

DID YOU KNOW...
There are over 6,000 species of earthworms worldwide.
Of the 180 species of earthworms in the United States and Canada, 60 are invasive.
Earthworms breath through their skin.
Baby earthworms emerge fully formed.

Human Impact

Human activity spread invasive species when fisherman dump live bait and garderners use living worms near forests as compost. These earthworms eventually lead to huge environmental changes by destroying the understory plants that native species depend on.