Hirudinea: India
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Hirudinea
Introduction
Leeches are widely distributed in the temperate and •wanner areas of the world and they are such familiar organisms that it is not surprising to find their description both in the ancient and modem literature of the leading nations of the world. Leeches are segmented wonns devoid of chaetae or parapodia, and with two suckers for attachment. They feed on blood. Leeches belong to the Class Hirudinea, which consists of two orders comprising five families and twenty five genera. So far fifty nine species including eight subspecies are known from the mainland of India.
In the order Rhynchobdellae, the leeches are mainly freshwater aild marine forms. Their size is generally from 6 mm to 20 mm in length and thus may escape the attention of the ordinary observer. These leeches have protrusible proboscis for sucking the blood and juices of therr prey.
The leeches of the Order Arhynchobdellae do not have protrusible proboscis. They are also called jawed leeches and the specialization has reached its maximum in this order. They are adapted to sanguivorous or predaceous habit. They are mainly freshwater and terrestrial. The length of the body varies from 10 cm to 40 cm.
Leeches are of two type, i.e. venomous and non-venomous. Venomous leeches are a menace to human beings and cattles. The non-venomous leeches have been used throughout the world as remedies for the throat and inflammatory swelling in human beings on account of their property of sucking blood in excess. Medicinal leeches have also been used for releasing the blood pressure in human beings. The species mostly used for this purpose is mainly Hirudo medicinalis. Beautifully coloured and ornamented leeches are also used as decorative pieces.
Historical Resume
(i) Pre-1900
The term Hirudinea was fast established by Lamarck in 1818. Although the reference to leeches have been found in the ancient and modern literature as back as 500 B.C. in the literature of Mahabharata, studies on Indian leeches has been almost negligible, but outside India work has been carried out regularly. The earliest record is that of Linnaeus (1758). Between the years 1758 and 1900 the important works include those by Blanchard (1887-1917), Whitman (1884-1892) and Moquin Tandon (1'826). The contributions in general included faunal list, taxonomy -often with anatomical details, distribution and field ecology. There were however, no exclusive studies on Indian leeches.
(ii)1901 to 1947
It is the most productive and significant period in the study of Indian Leeches. The important works on the Indian leech fauna were by Harding and Moore (1898-1927), Oka (1895-1925) and Chelladurai (1934). The only comprehensive work has been the Fauna of British India -Leeches by Harding & Moore (1927). In addition, Bhatia (1930-1940) has also contributed significantly on various aspects of leeches.
(iii)1948-1990
During the period between 1940 and 1950 there has been no work on this group. Later, Sanjeeva Raj (1951-1981); Baugh (1960) and Chandra (1967-1990) published accounts on the Mahesh Chandra, Zoological Survey of India, Solan systematics, ecology and distribution of Indian leeches. There were some occasional papers by Soota also.
Studies from Different Environs
Leeches occur in three types of ecosystems, marine, freshwater and terrestrial. The marine leeches were mainly studied by Sanjeeva Raj and the freshwater and terrestrial leeches have been thoroughly studied by Bhatia, Chandra, Soota and Baugh.
Leeches from Kashmir to Arunachal Pradesh, Rajasthan, Maharashtta, Himachal Pradesh and Northeast India were studied. Occasional records also exist from certain other states of India. The freshwater leeches have been studied from tanks, pools, lakes, hill streams and rivers. The terrestrial ones from tropical forests and deep forests of the Himalayas upto an altitude of 3000 mts. The leech fauna of Gujarat, Madhya Pradesh, Karnataka, Andhra Pradesh, Tamil Nadu and Orissa are poorly studied and needs a thorough survey.
Estimation of Taxa
Out of the seven recognised families of leeches, only five families viz. Piscicolidae, Glossiphonidae, Erpobdellidae, Hirudidae and Haemadipsidae are represented in India. The National Zoological Collections in the Zoological Survey of India comprise 59 species belonging to the above mentioned families. The family-wise breakup of Indian species of leeches are given below:
Out of S9 species, 32 species an: endemic.
Classified Treatment
Sanjeeva Raj gave comprehensive treatment of the Family Piscicolidae. Baugh and Bhatia have studied primarily the Family Glossiphonidae. Soota and Chandra have carried out researches on the whole group in respect of field ecology and extension of distributional records.
Current Studies
In the Zoological Survey of India, systematics and distribution of leeches of Himachal Pradesh of the Western Himalayan Ecosystem are currently under study.
Expertise India
In ZSI
G. C. Ghosh, ZSI, 27, J. N. Road, Calcutta -700 016. Mahesh Chandra, ZSI, High Altitude Field Station, Solan.
Elsewhere
P. J. Sanjeeva Raj, Madras.
Abroad
A. Soos, Budapest (Hungary); R. T. Sawyer, U. K.; L. R. Richardson, America.
Selected References Bhatia, M. L. 1939. On some leeches from Kashmir, Bull. Punj. Univ. Zool., 2 : 1-17. Chandra, M. 1983. A check-list of leeches of India. Rec. zool. Surv. India, 80 : 265-290. Harding, W. A. and Moore, P. J. 1927. The Fauna of British India. Hirudinea. Taylor and Francis,
London. Sanjeeva Raj, P. J. 1976. Review of fish-leeches of the Indian Ocean. J. mar. bioi. Ass. India, 16 (2) : 381-397
