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After mating, eggs are laid in cocoons where fertilization occurs.

Earthworms are hermaphrodites which means that they contain both male and female reproductive organs. After mating, eggs are laid in cocoons where fertilization occurs. After fertilization, the egg begins dividing. By the time an earthworm has reached the four celled-stage, the cellular material is already partitioned into different daughter cells. The fate of these cells has been determined and they would not be capable of developing into a complete organism if allowed to develop independently. In this article, we will learn about the digestive system and explore the functions of the associated smooth muscle. The region of interest contains the gizzard and the. These structures lie posterior to the oesophagus, which can be easily identified because it is encircled by enlarged blood vessels that function as hearts. The crop-gizzard is also partially obscured by the cream-coloured seminal vesicles of the reproductive system.

The digestive system of the earthworm comprises alimentary canal and glands along with physiology of digestion. Alimentary canal of earthworm The alimentary canal is long and extends from the mouth to anus. It consists of the following parts:

Typhlosole Divides the Intestine into 3 regions. They are:

Earthworms feed upon all kinds of debris and organic humus such as decaying leaves, microorganism etc. present in soil. They can feed directly on grasses and other vegetation as well. During feeding the buccal cavity is protruded out with the help of protractile and retractile muscle and the food is drawn into the mouth. The food enters into pharynx through the buccal cavity. The dorsal chamber of pharynx consists of the pharyngeal gland composed of chromophil cell which produces saliva containing mucin and protease. Mucin lubricates the food and turns it to soft food and protease converts protein into amino acids. The food particles then pass through the oesophagus into the gizzard, where it is ground and crushed into the fine state due to the contraction of circular muscles of the gizzard. The ground food material enters into the stomach where the neutralisation of food takes place by a calcification process. Also, the complete digestion of protein by proteolytic enzymes is carried out here. Now the food particles enter into the intestine. In the intestine, intestinal caeca produce amylase which converts starch into glucose. In Intestine several enzymes are secreted and act on the substrate as follows:

Digestion takes place mostly in the intestine and the digested food is absorbed by villi. Then it passes into the bloodstream through capillaries. The undigested food and the soil are released out in the form of casting through the anus.

Q1. Write a short note on the Pharynx of an Earthworm. Ans. Pharynx is the small, wide, thick-walled, pear-shaped chamber. Two chambers are found in pharynx. They are the dorsal chamber and ventral chamber. The dorsal or the salivary chamber which contains the pharyngeal gland composed of chromophil cells. These cells produce saliva containing proteolytic enzymes and mucin. Mucin softens the food soft protease breaks down proteins into amino acids. The ventral chamber is a conducting chamber which conducts digested or undigested food material from the pharynx to the oesophagus. The pharynx is used as a sucking and pumping organ during feeding. Q2. What are the functions of the Earthworm’s Digestive System? Ans. Earthworm Digestive System Functions: A summary: Food such as soil enters the earthworm’s mouth where it is taken up and swallowed by the pharynx. Then the soil passes through the oesophagus containing calciferous glands that release calcium carbonate to eliminate the earthworm’s body from extra calcium. After it passes through the oesophagus, the food particles move into the crop where it is stored and then travels into the gizzard. The gizzard uses stones that the earthworm eats to completely grind the food. The food moves into the intestines as gland cells in the intestine release fluids to aid in the digestive process. The intestinal wall has blood vessels where the absorption of the digested food takes place and is transported to the rest of the body. Q3. Describe the Digestive System of the Earthworm. Ans. Please refer to the article above

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