Earthworm-Morphology
Chapter Name : Structural Organization In Animals |
Sub Topic Code : 103_11_07_03_02 |
Topic Name : Earthworm-Morphology |
|
Sub Topic Name : Alimentary Canal |
|
Introduction
The body wall of the earthworm is covered externally by a thin non-cellular cuticle below which is the epidermis, two muscle layers (circular and longitudinal) and an innermost coelomic epithelium. The epidermis is made up of a single layer of columnar epithelial cells which contain secretory gland cells.
Pre-Requisites:
To understand the digestive system of earthworm.
Activity:
Videos which show how digestive system of earthworm works.
Real Life Question:
what kind of food does earthworm eat.
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| alimentary canal | straight tube and runs between first to last segment of the body. |
| buccal cavity | 1-3 segments |
| oesophagus | 5-7 segments. |
| muscular gizzard | 8-9 segments, It helps in grinding the soil particles and decaying leaves, etc. |
| Stomach | 9-14 segments. The food of the earthworm is decaying leaves and organic matter mixed with soil. Calciferous glands, present in the stomach, neutralize the humic acid present in humus. |
| Intestine | 15th segment onwards and continues till the last segment. |
| typhlosole | characteristic feature of the intestine between 26-35 segments is the presence of internal median fold of dorsal wall, increases the effective area of absorption in the intestine. |
| Anus | The alimentary canal opens to the exterior by a small rounded aperture |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|
Practical examples around us
| Examples | Explainations |
|---|
What you learn in Theory:
The different parts of digestive system in earthworm.
What you learn in Practice:
How the different parts help in digestion of food in earthworm.