zoology-imp -questions

a)Pre-typhlosolar region:- Typhlosole is absent
b) Typhlosolar region:- Typhlosole is present
c)Post-typhlosolar region;- Typhlosole is absent , it is also called rectum. It opens to the out side through anus.
Anus :- It is present in the last segment.

CIRCULATORY SYSTEM IN FIRST 13 SEGMENTS:-
BLOOD CIRCULATORY SYSTEM IN THE FIRST 13 SEGMENTS OF PHERETIMA
ARRENGEMENT OF BLOOD VESSELS IN THE FIRST 13 SEGMENTS OF PHERETIMA:-
In the first 13 segments of Pheretima the following bloodvessels are present
I)Longitudinal blood vessels II) The hearts
III)The anterior loops IV)Ring vessels
I) Longitudinal blood vessels:
There are 5 longitudinal trunks in Pheretima in its first 13 segments,they are :
1.One Dorsal blood vessel 2.One Ventral blood vessel
3.Two lateral oesophageal blood vessels
4.One supra oesophageal blood vessel
1. Dorsal blood vessel:
a.It is the largest blood vessel
b.It is muscular
c.It is contractile
d.It is valvular
e.Blood flows from posterior to anterior
f.It acts as a distributing blood vessel in the first 13 segments
g.It distributes blood to parts of alimentary canal from buccal cavity to stomach and pharyngeal nephridia
2.Ventral blood vessel:-
a.It is the longest blood vessel
b.It is nonmuscular
c.It is noncontractile
d.It is nonvalvular
e.Blood flows from anterior to posterior
f.It is a chief distributing blood vessel
g.It distributes blood to bodywall,septa,integumentary nephridia,repeoductive organs in the first 13 segments
3. Lateral oesophageal blood vessels:
a.One pair of lateral oesophageal blood vessels present either side of alimentary canal in the first 13 segments
b.These blood vessels collect blood from bodywall,septa,integumentary nephridia,repeoductive organs in the first 13 segments
4. SUPRA OESOPHAGEAL BLOOD VESSEL:-
a.It is located between 9 th segment to 13 th segment
b.It collects blood from gizzard ,stomach and lateral oesophageal blood vessel
c.From supra oesophageal blood vessel blood flows into ventral blood vessel through lateral oesophageal hearts.
II) THE HEARTS :-
a.There are four pairs of hearts in Pheretima
b.The first two pairs are located in the 7 th and the 9 th segments
c.Remaining two pairs are located in the 12 th and the 13 th segments
III)THE ANTERIOR LOOPS :
There are two pairs of anterior loops present in the 10 th and the 11 th segment between supraoesophageal blood vessel and lateral oesophageal blood vessel
IV)RING VESSELS :
They are present in the 10th,11th,12th and 13th segments between between supraoesophageal blood vessel and lateral oesophageal blood vessel