Circulatory System of Earthworm

What is the Circulatory System of Earthworm?

The earthworm's circulatory system is a closed type. It means that the blood flows only through a series of vessels and does not come into direct contact with the body tissues. The circulatory system is responsible for the transportation of food, gases, and waste products in and about the body. Such an arrangement allows for more efficient transportation of oxygen and nutrients to the various organs and tissues.

Components of Circulatory System

The circulatory system consists of components: blood vessels, a heart made up of a series of aortic arches, and blood. These combined elements ensure the proper flow of materials throughout the earthworm's body.

Blood Vessels

• The two main kinds of blood vessels found in earthworms are the dorsal blood vessels and the ventral blood vessels.

• The former is along the top of the body, picking up blood from the posterior segments.

• On the other hand, the latter runs underneath the alimentary canal, delivering blood to the body segments.

Aortic Arches (Hearts)

• Earthworms have five pairs of aortic arches which function as hearts.

• The primary purpose of these hearts is to push the blood from the dorsal vessel to the ventral vessel, thus maintaining a continuous blood flow without an interrupted circulation system.

Blood Composition (Haemoglobin in Plasma)

• The blood of the earthworm is red in colour, as it contains haemoglobin in the plasma.

• Haemoglobin plays a vital role in carrying oxygen to various parts of the body for the metabolism of the earthworm's various activities.

Blood Glands (Segments 4–6)

• Blood glands in segments 4-6 produce blood cells as well as haemoglobin which is essential in the transport of oxygen.

• These glands are indeed crucial in maintaining healthiness as well as functionality of the circulatory system.

Direction of Blood Flow in Earthworm

The blood flow is unidirectional in earthworms. Blood is pumped from the dorsal vessel into the aortic arches and then into the ventral vessel, and circulation within the body is very effective.

Significance of Circulation in Earthworm

The significance of circulation in Earthworm is:

• It transports nutrients, gases, and waste products necessary for metabolic activities and good health of the earthworm.

• It helps in the regulation of the internal environment, ensuring homeostasis of the earthworm.

Comparison with Other Organisms

Different organisms have evolved different circulatory systems. Let’s take a look at the differences between the circulatory systems of different organisms.

Earthworm vs Insects (Closed vs Open System)

The earthworm's closed circulatory system is much more efficient compared with the open systems found in most invertebrates.

Earthworm vs Humans

Although both earthworms and humans have closed circulatory systems, they differ in structure and the level of complexity.

Circulatory System of Earthworm NEET MCQs (With Answers & Explanations)

Important topics for NEET are:

• Components of Circulatory System (Aortic arches)

• Comparison with Insects

• Comparison with Humans

Practice Questions for NEET

Q1. The type of circulatory system present in earthworms is

1. Closed

2. Open

3. Double

4. Both 2 and 3

Correct answer: 1) Closed

Explanation:

The circulatory system in the Annelida - Blood vascular system is of a closed type. The circulatory system in Annelida is a closed type, meaning blood flows within a network of vessels throughout the body. It consists of dorsal and ventral blood vessels connected by lateral vessels, ensuring efficient circulation. The dorsal vessel functions as the main pumping organ, moving blood anteriorly, while the ventral vessel distributes it posteriorly. Blood contains haemoglobin dissolved in plasma, aiding oxygen transport. This system supports efficient nutrient distribution and waste removal, critical for the survival of annelids in various environments.

Hence, the correct answer is option 1) closed.

Q2. One very special feature in the earthworm Pheretima is that:

1. It has a long dorsal tubular heart

2. Fertilization of eggs occurs inside the body

3. The typhlosole greatly increases the effective absorption area of the digested food in the intestine

4. The S - shaped setae embedded in the integument are the defensive weapons used against the enemies.

Correct answer: 3) The typhlosole greatly increases the effective absorption area of the digested food in the intestine

Explanation:

In Pheretima, commonly known as the earthworm, the long dorsal tubular heart is part of the circulatory system and is responsible for pumping blood throughout the body. It is not involved in the absorption of digested food. The absorption of nutrients occurs in the intestine, where a structure called the typhlosole, a dorsal internal fold, increases the surface area, allowing for more effective nutrient absorption.

Hence, the correct answer is option 3) typhlosole greatly increases the effective absorption area of the digested food in the intestine.

Q3. The dorsal vessel of the earthworm is

1. 1st thirteen

2. 13th to last

3. 18th to 21st

4. 1st fifteen

Correct answer: 1) 1st thirteen

Explanation:

The dorsal vessel of the earthworm is distributed in 1st thirteen segments and collected in the rest. The earthworm's biggest blood vessel, the dorsal vessel, is in charge of gathering and delivering blood throughout the body:

The dorsal vessel extends the length of the earthworm's body and is situated above the alimentary canal. Through the earthworm's thin, semi-transparent body wall, it appears as a dark line.

Hence, the correct answer is option 1) 1st thirteen.

Also Read:

• MCQs on Circulatory System

• Epithelial tissue

• Respiratory System in Cockroach