Earthworm Circulatory System Short Notes

Earthworm Circulatory System Short Notes

In this article we will discuss about the earthworm circulatory system

Earthworm Circulatory System

  • Earthworm circulatory system is closed type
  • Earthworm circulatory system consists of blood vessel, heart, capillaries and blood glands
  • Blood is composed of fluid plasma and colourless blood cells
  • Blood is red in colour due to the presence of haemoglobin
  • Haemoglobin occurs dissolved in plasma
  • Circulation occurs in one direction

Main Longitudinal Blood Vessels

Dorsal vessel

  • Dorsal vessel is extends through the length of the body
  • Dorsal blood vessel is largest, thickest and having contractile muscular walls
  • Flow of blood is from posterior to anterior
  • It has a pair of valves internally which check the backward flow of blood
  • It gives off branches that supply the blood to the anterior regions of the body

Ventral vessel

  • Ventral vessel is found below the alimentary canal and above the ventral nerve cord
  • Runs from second segment to the last segment of the body
  • Ventral vessel has thin wall and lacks muscles and valves
  • Flow of blood is anterior to posterior side
  • It supplies the blood to ventral body wall, septal nephridia and reproductive organs

Hearts And Anterior Loop

  • The hearts are contractile and surround the alimentary canal
  • They are present in the segments 7th , 9th , 12th and 13th

Lateral hearts

  • Pair of lateral hearts present in 7th and 9th segment
  • Lateral hearts permits blood to flow downwards only
  • It sends blood from dorsal vessel to ventral vessel

Lateral oesophageal hearts

  • Lateral oesophageal hearts present in 12th and 13th segment
  • These valves allow flow of blood to downwards only
  • Sends blood from supraoesophageal and dorsal vessel to ventral vessel

Blood Gland and Circulation

Blood glands

  • In the segments 4, 5, and 6 segments above pharynx are found small, red-colored the blood glands.
  • These glands manufacture blood cells and hemoglobin
  • In addition, these may perform excretory function in some species

Circulation of Blood

  • The circulation of blood through different vessels is carried out by the peristaltic contraction of heart.
  • In front of each septum, there is a pair of ring valves which direct the blood forward or backward but prevent reverse flow

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