The document summarizes the circulatory system of earthworms. It has a closed circulatory system with blood vessels that form distinct patterns in the intestinal and anterior regions. In the intestinal region, the main blood vessels are the dorsal, ventral, and subneural vessels which connect via commissural vessels. They supply and collect blood from the intestine, body wall, and other structures. The intestine also contains an external and internal plexus of capillaries. In the anterior region, the main blood vessels are the longitudinal, latero-oesophageal, supra-oesophageal and ventral vessels which supply blood to organs like the pharynx and gonads.

1. Earthworm
circulatory system
V.D.Dethe

2. • Closed type: closed blood vessel
• Hemoglobin strongly bind to oxygen
• Blood flows in circuit
• Pharynx –blood glands are present

3. • A. Blood vessels and their arrangement in the segments behind 13th,
i.e., intestinal region.
• B. Blood vessels and their arrangement in the anterior thirteen
segments.

4. • Blood vessels in intestinal region: behind 13th segments
In this blood vessels shows metameric arrangement (they are same in
all segment)
The blood vessels of this region include:
(i) Dorsal Vessels:
(ii) Ventral Vessels:
(iii) Subneural blood vessels

5. Blood vessels in Intestinal region
Subneural
blood vessels
Ventral blood
vessels
Dorsal blood
vessels
commissural
blood vessels
Dorso intestinal
blood vessels
Ventro-
tegumentry
Ventro-
intenstinal
Collect from
body wall
septa and
nephridia
Collects blood
from
intenstine
Supply blood
to body wall,
nerve cord ,
integumentary
nephridia
Supply blood
to intestine
Supply blood
to intenstine

6. Dorsal Blood Vessels:
• Largest , runs mid dorsally above alimentary canal. It has thick muscular
contractile wall and pair of valve in each segments infront of septum.
• This is collecting vessel in intestinal region, receives a pair of
commissural and dorsal intenstinal in each segments.
• Commissural vessels: The commissural vessels form a loop behind each
septum and they receive blood from the body wall, nephridia and
prostrate glands, septa and nephredia. The commissural vessels also
supply blood to intenstine a septointestinal branch to the intestine.
Opens in to dorsal surface of dorsal vessels.

8. • Dorso –intenstinal: in each segment two vessels collects blood from
intenstine opens on ventral surface of dorsal vessel. Valves prevent
backflow of blood.

9. Ventral blood vessels
Large vessels, running midventrally below alimentary canal , ant. to post.
Non- contractile, thin walled, distributing vessels supply blood to
alimentary canal and body wall.
It gives pair off ventro tegumentaries and ventro-intestinal
• Ventro-tegumentaries: originates from ventral vessels , goes in septum of
segments. Supply blood to body wall, nerve cord , and integumentary
nephridia.
• ventro-intestinal : supplies blood to the intenstine.

10. Subneural blood vessels
• Situated ventrally below nerve cord , formed by union of two latero-
oesophageal, collecting vessels , collecting blood from ventral body
and nerve cord .

11. 2. Intestinal Blood Plexus:
• The intestine of Pheretima is richly supplied with blood capillaries which
form network.
• two capillary networks in the intestine:
• (i) The external and
• (ii) The internal.
• The capillary network which is present at the outer surface of intestine is
known as external plexus which receives blood from the ventral vessel
through ventrointestinal and passes it on to the internal plexus.
• The capillary network which is present between the circular muscle layer of
intestine and its internal epithelial lining is known as internal plexus which
serves to absorb the nutrients from the gut and is connected with dorsal
blood vessel through the dorsointestinals

12. Blood vascular system in first 13 segments
3 blood vessels
• Longitudinal blood vessels
• Four pairs of heart
• Two pairs of anterior loops

14. Longitudinal blood vessels
Supra oesophageal
blood vessels
Ventral vessels
Dorsal vessels Latero oesopahageal
vessels
Supply blood to
buccal chamber,
pharynx,gizzard,
oesophagus and
spermathecae
Thick,muscular
Branches in 3,4,5,8
segments.
Supply blood to body
wall, septal nephridia,
spermathacae, seminal
visecles, testis sac,
varies,
Thin,non.contractile
(ventro tegumentry)
Pair of vessels at ventro
lateral side 2 to 13
segments ,
Collecting vessels
receive blood from
wall, buccal chamber,
pharynx,gizzard,
oesophagus and
gonads
Unpaird, short vessels
in9-13 segments,
distributing vessels and
collecting vessels
Collects blood from
gizzard and stomach