CLASSIFICATION OF HIRUDO MEDICINALIS
PHYLUM :- ANNELIDA (Metamerically segmented, coelomate and laterally symmetrical. )
CLASS :- CLITELLATA (having a clitellum – the ‘collar’ that forms a reproductive cocoon during part of their life cycles)
SUB-CLASS :- HIRUDINEA (Annelids with fixed segments, without parapodia and with anterior and posterior
ORDER :- ARCHYNCHOBDELLIDA OR GNATHOBDELLIDA (Proboscis non-protrusible; jaws present.)
FAMILY :- HIRUDINIDAE
GENUS :- Hirudo
SPECIES :- medicinalis
It has cosmopolitan distribution. Found in India, Myanmar, U.K. and U.S.A.
HABIT AND HABITAT
Hirudo medicinalis is found in ponds, marshes and streams. They are Sangivorous (blood sucking) ectoparasites on submerged cattles.
GENERAL CHARACTERSTICS OF HIRUDO MEDICINALIS
- Commonly known as Indian cattle leech.
- Body is cylindrically elongated dorsoventrally flattened having variable pigments on dorsal surface, measuring 40 cm.
- Anterior and posterior suckers are well developed and are meant for attachment
- Anterior sucker is formed by prostomium and rest of the body contains about 95 superficial segments or annuli and 36 to 37 true segments.
- Segments 3, 4 and 5, 6 have 2 and 3 annuli each, respectively.
- Rest of the segments have 5 annuli each. The first 5 segments have 5 pairs of small eyes in the first annulus.
- First annulus of each segment contains segmental papillae.
- Posterior end contains posterior sucker formed by the union of 7 segments. The entire animal is divided into cephalic, preclitellar, clitellar, middle, caudal regions and posterior sucker.
- Mouth is found as a narrow, tri-radiate aperture opening in the pre-oral chamber. Nephridiopores are found ventrally on the last annulus of each segment from 6 to 22. The coelom is replaced by spongy botryoidal tissue. The coelom is reduced in the form of 4 channels, called as haemocoelomic channels.
- Hermaphroditic. Development takes place in cocoons or ootheca. Male and female genital pores are on 10th and 11th segments respectively.
In old days, Hirudo was used by physicians to suck the blood of some ill persons, because they believed illness was due to some sort of imbalance in body fluids. In the mouth are three cutting teeth that make a V-shaped incision in the skin. Numerous small salivary glands around the mouth setcrete a substance that prevents the coaguiation of blood. This substance called Hirudin is commercially extracted from leeches and used medicinally when anticoagulants are indicated.
The animal contains 36-37 segments, and all above features hence it is Hirudo medicinalis.