THE BIOLOGY OF WOOD-BORING TEREDINID MOLLUSCS
475
1959) wharves, stakes, poles, etc., wooden water tanks in ships (Kirkbride, 1922) as well as oyster culture equipment (Nelson, 1922, 1924a ;
Roughley, 1925, 1925a; Needler and Needler, 1940; Needler, 1941).
XIX. DETECTION AND PREVENTION OF SHIPWORM ATTACK
The protected, entombed life of shipworms has necessitated special
and sometimes novel devices to detect their presence. In their natural
habitat they may be found with the help of divers (Clapp, 1936) who
can look out for the display of siphons. Since these borers produce a
characteristic rasping sound while abrading wood, engineers use
electrical stethoscopes and microphones to detect them during inspection of piles (Anon, 1926 ; Tarasov, 1943). X-ray photography has
also been employed for the detection and study of shipworms (Ralph
and Hurley, 1952). The utilization of stereo-radiography by adding the
third dimension was more successful in clearly demarcating the intertwining burrows (Crisp et al., 1953). These methods have facilitated not
only detection in timbers but also details regarding the growth rates of
the calcium-lined burrows without damaging the substrate and
disturbing the animals. In Ohio, gamma rays (Cobalt 60 and Iridium
192) have been used for the radiographic inspection of underwater
sections of piles (Jelley, 1953).
Since the beginning of man's maritime activity, he has been trying
every known mechanical, chemical, electrical and biological means t o
deter, discourage or destroy these pests. As early as 1697, Dampier, in
his account of his voyages round the world, describes a method, believed by the natives of Mindanao in the southern Philippines to be
effective in checking their attacks. Drydocking the vessel soon after
each voyage, they char the vessel's outer bottom with a view to drying
it completely. This they claim to be a preventive measure. An identical
method has been practised by the fishermen of Bengal who suspend the
boat infested by shipworms across two poles and light a fire beneath
to destroy them. The charring of the bottom hinders further attack for
a period (Wright, 1864). This method is based on the fact that desiccation is fatal for these soft bodied creatures and is practised with
suitable modifications in various countries. In Sydney timbers have
thus been treated with the " Carbo-Teredo " process (Anon, 1916,
1917) which consists of impregnating the timber with a hydrocarbon
and then charring the outer surface by means of a heater rather than by
open fire (Cunningham, 1920, 1923). This method has been found
effective for certain types of timber (Hamer, 1920, 1923, 1924, 1925;
Holderness, 1931). Since desiccation is fatal to shipworms this end could
475
1959) wharves, stakes, poles, etc., wooden water tanks in ships (Kirkbride, 1922) as well as oyster culture equipment (Nelson, 1922, 1924a ;
Roughley, 1925, 1925a; Needler and Needler, 1940; Needler, 1941).
XIX. DETECTION AND PREVENTION OF SHIPWORM ATTACK
The protected, entombed life of shipworms has necessitated special
and sometimes novel devices to detect their presence. In their natural
habitat they may be found with the help of divers (Clapp, 1936) who
can look out for the display of siphons. Since these borers produce a
characteristic rasping sound while abrading wood, engineers use
electrical stethoscopes and microphones to detect them during inspection of piles (Anon, 1926 ; Tarasov, 1943). X-ray photography has
also been employed for the detection and study of shipworms (Ralph
and Hurley, 1952). The utilization of stereo-radiography by adding the
third dimension was more successful in clearly demarcating the intertwining burrows (Crisp et al., 1953). These methods have facilitated not
only detection in timbers but also details regarding the growth rates of
the calcium-lined burrows without damaging the substrate and
disturbing the animals. In Ohio, gamma rays (Cobalt 60 and Iridium
192) have been used for the radiographic inspection of underwater
sections of piles (Jelley, 1953).
Since the beginning of man's maritime activity, he has been trying
every known mechanical, chemical, electrical and biological means t o
deter, discourage or destroy these pests. As early as 1697, Dampier, in
his account of his voyages round the world, describes a method, believed by the natives of Mindanao in the southern Philippines to be
effective in checking their attacks. Drydocking the vessel soon after
each voyage, they char the vessel's outer bottom with a view to drying
it completely. This they claim to be a preventive measure. An identical
method has been practised by the fishermen of Bengal who suspend the
boat infested by shipworms across two poles and light a fire beneath
to destroy them. The charring of the bottom hinders further attack for
a period (Wright, 1864). This method is based on the fact that desiccation is fatal for these soft bodied creatures and is practised with
suitable modifications in various countries. In Sydney timbers have
thus been treated with the " Carbo-Teredo " process (Anon, 1916,
1917) which consists of impregnating the timber with a hydrocarbon
and then charring the outer surface by means of a heater rather than by
open fire (Cunningham, 1920, 1923). This method has been found
effective for certain types of timber (Hamer, 1920, 1923, 1924, 1925;
Holderness, 1931). Since desiccation is fatal to shipworms this end could