THE BIOLOGY OB WOOD-BORING TEREDINID MOLLUSCS
341
Nagabhushanam (1958, 1960), Ganapati and Lakshmana Rao (1959).
No less than 13 species of shipworms seem to exist in that region,
Bankia campanellata and Teredo furcifera being by far the most important from the standpoint of destruction at Visakhapatanam
Harbour.
Along the Madras coast 20 species are apparently active of which
only 4 occur in any abundance (Nair, 1954, 1955, 1956b). The most
important forms infesting the fishing floats are Bankia carinata and
Teredora princesae and along the coast Teredo furcifera and Uperotus
rekderi are destructive. Uperotw clavus infests the floating seeds of the
mangrove and these are cast ashore in large numbers during the monsoons (Gravely, 1941 ; Nair, 1954).
Nearly seven species are active in and around Bombay (Palekar,
1956; Palekar and Bal, 1955, 1957, 1957a, Becker, 1958). The dominant forms here are different from those in other localities. According
to recent reports most of the destruction is caused by Dicydhifer
manni, Bankia rochi and also by Teredo furcqera.
Only 8 species of shipworms have so far been collected from the
south-west coast of India. In the environs of Cochin Harbour, a typical
tropical estuary, the most destructive species are Nausitora hedleyi and
Teredo furcifera (Nair, 1965, 1966).
There is thus a marked difference in the occurrence and distribution
of species along the east and west coasts of India. Recently Panikkar
(1969) has tried to explain the differences in the nature and composition of the fauna of these coasts. According to Panikkar, " the
estuarine, and to some extent, the shore fauna of the west coast of
India, suffers from partial or complete destruction during the South
West monsoon period and that this is followed by an annual repopulation of the estuaries and backwaters after the monsoon months.
With the cessation of the rainy season when heavy run-over of fresh
water to the sea takes place, more stable conditions prevail in later
months in the estuaries which slowly build up a saline regime."
The occurrence, abundance and activity of the borers show remarkable variations and fluctuations in the different harbours of India, each
having its own dominant set of species and an assemblage of less important forms. It is well known that reactions of closely allied species
may be different and even individuals of the same species may vary
according to the peculiar hydrographic conditions prevailing in an area.
It is noteworthy that each species has its characteristic preferences,
distinctive life history and seasons of settlement. Generalizations
should therefore be made with great caution and a scheme evolved after
elaborate study and experimentation for one locality may prove in-
341
Nagabhushanam (1958, 1960), Ganapati and Lakshmana Rao (1959).
No less than 13 species of shipworms seem to exist in that region,
Bankia campanellata and Teredo furcifera being by far the most important from the standpoint of destruction at Visakhapatanam
Harbour.
Along the Madras coast 20 species are apparently active of which
only 4 occur in any abundance (Nair, 1954, 1955, 1956b). The most
important forms infesting the fishing floats are Bankia carinata and
Teredora princesae and along the coast Teredo furcifera and Uperotus
rekderi are destructive. Uperotw clavus infests the floating seeds of the
mangrove and these are cast ashore in large numbers during the monsoons (Gravely, 1941 ; Nair, 1954).
Nearly seven species are active in and around Bombay (Palekar,
1956; Palekar and Bal, 1955, 1957, 1957a, Becker, 1958). The dominant forms here are different from those in other localities. According
to recent reports most of the destruction is caused by Dicydhifer
manni, Bankia rochi and also by Teredo furcqera.
Only 8 species of shipworms have so far been collected from the
south-west coast of India. In the environs of Cochin Harbour, a typical
tropical estuary, the most destructive species are Nausitora hedleyi and
Teredo furcifera (Nair, 1965, 1966).
There is thus a marked difference in the occurrence and distribution
of species along the east and west coasts of India. Recently Panikkar
(1969) has tried to explain the differences in the nature and composition of the fauna of these coasts. According to Panikkar, " the
estuarine, and to some extent, the shore fauna of the west coast of
India, suffers from partial or complete destruction during the South
West monsoon period and that this is followed by an annual repopulation of the estuaries and backwaters after the monsoon months.
With the cessation of the rainy season when heavy run-over of fresh
water to the sea takes place, more stable conditions prevail in later
months in the estuaries which slowly build up a saline regime."
The occurrence, abundance and activity of the borers show remarkable variations and fluctuations in the different harbours of India, each
having its own dominant set of species and an assemblage of less important forms. It is well known that reactions of closely allied species
may be different and even individuals of the same species may vary
according to the peculiar hydrographic conditions prevailing in an area.
It is noteworthy that each species has its characteristic preferences,
distinctive life history and seasons of settlement. Generalizations
should therefore be made with great caution and a scheme evolved after
elaborate study and experimentation for one locality may prove in-