The document discusses the digestive system of earthworms. It notes that earthworms are burrowers that live in soil and feed on organic matter, helping to increase soil fertility. It then describes the main components of an earthworm's alimentary canal, which functions as its digestive system. The canal contains a mouth, buccal cavity, pharynx, esophagus, gizzard, stomach, and intestine, each of which aids in ingestion and digestion.

1. PATHERKANDI COLLEGE , PATHERKANDI

3.  Earthworm are externally segmented.
 An earthworm is a reddish brown terrestrial
invertebrate that belongs to the phylum Annelida.
INTRODUCTION

4. HABIT AND HABITAT OF EARTHWORM
 The earthworms are burrowers. It prefers to live in the burrow
during the day and comes out at night.
 They feed on organic matter present in the soil and the undigested
substances are expelled in the form of castings.
 Earthworms are generally known as farmer’s friend as they help to
increase the fertility of soil and burrowing aids in adequate aeration
of the soil.

5. • Digestive System :-
Earthworm consists of alimentary canal
and digestive gland.
• Alimentary Canal :-
The alimentary canal runs as a straight
tube throughout the length of the body from the
mouth to anus.
DIGESTIVE SYSTEM OF EARTHWORM

6. Alimentary canal consists of a following
types :-
* Mouth
* Buccal cavity
* Pharynx
* Oesophagus
* Gizzard
* Stomach and
* Intestine

7. MOUTH :-
o Mouth is situated in the first
segment .
o Ingestion of food takes
place through the mouth.
BUCCAL CAVITY :-
o Buccal cavity situated in the
2nd or 3rd segment.
o It is a short, wide and thin
walled tube.

8. PHARYNX :-
o It extends upto the 4th segments .
o It act as a pump during feeding .
OESOPHAGUS :-
o It extends from the 5th segment to
the 7th segment .
o It helps to passes the food particles
from the pharynx to the gizzard .

9. GIZZARD :-
o It is oval, thick walled and
highly muscular organ lying in
the 8th to 9th segment .
o Gizzard grinds the food with
the help of thick muscles and
cuticle .
STOMACH :-
o It extends from the 10th to the
14th segment .
o The stomach has a calciferous
gland that helps in
neutralization of the food by
calcification process .

10. INTESTINE :-
oIt extends from the 15th to the last segment .
oThe intestine is a long, and thin walled