342
N. BALAKRISHNAN NAIFi AND M. SARASWATHY
applicable for another. Species density has fluctuated over long periods
and within the same period their attacks have differed considerably in
various locations along the same stretch of coast (Becker, 1958). So the
problem varies with the species occurring in any locality and also with
climatic and hydrographic conditions. The vagaries and discriminations
of these pests are such that most of the conclusions drawn from any
investigation must usually be considered as purely of local application
and the experience gained from one locality cannot necessarily be
applied to another. Each harbour or geographical location needs a
special set of specifications for the treatment of timber owing to the
difference in the species of borers prevalent, the condition of the water,
degree of pollution, etc.
Table I1 gives the distribution of shipworms in'the Indian Ocean.
According to revised estimates nearly 35 species occur. So as to present
the nature of their distribution, the land masses bounding the Indian
Ocean have been tentatively divided into four regions: Region I, East
Coast of Africa, Madagascar, Red Sea and Persian Gulf; Region 11,
India and Indian Ocean Islands; Region 111, Burma, Malaysia and
Indonesia ; Region IV, Australia and New Zealand. It is evident from
the table that even though species are not uniformly distributed, the
records of certain species do indicate wide distribution extending from
the East Coast of Africa to Australia and New Zealand. The 35 species
noted from the area may be grouped into nine categories, on the basis
of this distribution.
(1) Species which have been recorded from all the four regions:
Dicyathifer manni, Uperotus clavus, Lyrodus pedicellatus, Nausitora
dunlopei .
(2) Species common for Regions I, I1 and I11 but not recorded from
Region IV: Teredora princesae, Teredo furcifera, T . fulleri, T . clappi,
Lyrodus massa, Bankia rochi, B . bipalmulata.
(3) Species which are common for Regions 11, I11 and I V : Bactronophorus thoracites, Nototeredo edax.
(4) Species which are common for Regions I and I1 only: Teredoth yra smithi .
( 5 ) Species common for Regions I1 and I11 only: Lyrodus aflinis,
Nausitora hedleyi, Bankia campanellata, B . carinata.
( 6 ) Species which are common for Regions I11 and IV only : Teredo
navaliis.
( 7 ) Species which occur in Regions I and I11 only : Teredothyra
matocotana, Spathoteredo obtusa.
N. BALAKRISHNAN NAIFi AND M. SARASWATHY
applicable for another. Species density has fluctuated over long periods
and within the same period their attacks have differed considerably in
various locations along the same stretch of coast (Becker, 1958). So the
problem varies with the species occurring in any locality and also with
climatic and hydrographic conditions. The vagaries and discriminations
of these pests are such that most of the conclusions drawn from any
investigation must usually be considered as purely of local application
and the experience gained from one locality cannot necessarily be
applied to another. Each harbour or geographical location needs a
special set of specifications for the treatment of timber owing to the
difference in the species of borers prevalent, the condition of the water,
degree of pollution, etc.
Table I1 gives the distribution of shipworms in'the Indian Ocean.
According to revised estimates nearly 35 species occur. So as to present
the nature of their distribution, the land masses bounding the Indian
Ocean have been tentatively divided into four regions: Region I, East
Coast of Africa, Madagascar, Red Sea and Persian Gulf; Region 11,
India and Indian Ocean Islands; Region 111, Burma, Malaysia and
Indonesia ; Region IV, Australia and New Zealand. It is evident from
the table that even though species are not uniformly distributed, the
records of certain species do indicate wide distribution extending from
the East Coast of Africa to Australia and New Zealand. The 35 species
noted from the area may be grouped into nine categories, on the basis
of this distribution.
(1) Species which have been recorded from all the four regions:
Dicyathifer manni, Uperotus clavus, Lyrodus pedicellatus, Nausitora
dunlopei .
(2) Species common for Regions I, I1 and I11 but not recorded from
Region IV: Teredora princesae, Teredo furcifera, T . fulleri, T . clappi,
Lyrodus massa, Bankia rochi, B . bipalmulata.
(3) Species which are common for Regions 11, I11 and I V : Bactronophorus thoracites, Nototeredo edax.
(4) Species which are common for Regions I and I1 only: Teredoth yra smithi .
( 5 ) Species common for Regions I1 and I11 only: Lyrodus aflinis,
Nausitora hedleyi, Bankia campanellata, B . carinata.
( 6 ) Species which are common for Regions I11 and IV only : Teredo
navaliis.
( 7 ) Species which occur in Regions I and I11 only : Teredothyra
matocotana, Spathoteredo obtusa.