434
N. BALAERISJ3NAN NAIR AND M. SARASWATHY
glycogen, proteins, total nitrogen and non-protein nitrogen as well as
estimations of pooled monthly samples for lipid, sodium chloride, ash,
calcium and phosphorus are presented in Table IX. Average monthly
salinity and the average monthly gonad index are also presented. The
water content varied from 57.04-83-60%, with an average from specimens of varying sizes collected throughout the year of 71.49% for
this species. For marine species of Teredo, Lasker and Lane (1953)
found the water content to be 73% at Biscayne Bay, Florida. The
relatively low values obtained appear unique among the Bivalvia (see
Vinagradov, 1953) and are probably due t o the peculiar habitat, indicative possibly of the stress of high salinity on the life and activity of this
shipworm. The influence of salinity on the water content of N . hedleyi is
shown in Fig. 42. Venkataraman and Chari (1951) and Durve and Bd
(1 961) have reported a reciprocal relationship between water content
and such organic constituents as fat, glycogen and protein in oysters.
A n inverse relationship between the water content of the body and the
salinity of the ambient water was evident. It was also observed that the
water content in females was higher than in males and that the range of
fluctuation was more conspicuous in the former. Glycogen is an important food reserve of many marine molluscs being needed for reproduction, growth and maintenance. Glycogen values were notably high during the non-breeding months especially during February
to May when they fluctuated between 33-35 and 52.22% of the dry
weight of the animal. From June to January the values were comparatively low. On the onset of the breeding season there was a perceivable fall in the glycogen content, probably owing to the initial mas8
spawning during June. After January the values were comparatively
high and reached the highest value for the year in March.
Some animals bore into timber for protection only but shipworms
digest and metabolize the cellulose of the wood into which they bore
and exploit it as a source of nourishment. This unusual ability is
attended with several morphological and physiological adaptations
associated with the new conditions of habitat and food involving
changes in metabolism necessitated by a diet that is chiefly carbohydrate (Dore and Miller, 1923 ; Boynton and Miller, 1927 ; Lane, 1955;
Nair, 195513, 1955~) 1956c, 1957b). The concentration of glycogen which
is even higher than that present in very " fat )' oysters has already
been reported by Lane et al. (1952) who report as high a value as
58.2%. Greenfield (1953) has shown that glycogen constitutes 30% of
the dry weight of Teredo. Scrutiny of individual values in our studies
shows that glycogen value in some specimens may reach 59.12% in
N. BALAERISJ3NAN NAIR AND M. SARASWATHY
glycogen, proteins, total nitrogen and non-protein nitrogen as well as
estimations of pooled monthly samples for lipid, sodium chloride, ash,
calcium and phosphorus are presented in Table IX. Average monthly
salinity and the average monthly gonad index are also presented. The
water content varied from 57.04-83-60%, with an average from specimens of varying sizes collected throughout the year of 71.49% for
this species. For marine species of Teredo, Lasker and Lane (1953)
found the water content to be 73% at Biscayne Bay, Florida. The
relatively low values obtained appear unique among the Bivalvia (see
Vinagradov, 1953) and are probably due t o the peculiar habitat, indicative possibly of the stress of high salinity on the life and activity of this
shipworm. The influence of salinity on the water content of N . hedleyi is
shown in Fig. 42. Venkataraman and Chari (1951) and Durve and Bd
(1 961) have reported a reciprocal relationship between water content
and such organic constituents as fat, glycogen and protein in oysters.
A n inverse relationship between the water content of the body and the
salinity of the ambient water was evident. It was also observed that the
water content in females was higher than in males and that the range of
fluctuation was more conspicuous in the former. Glycogen is an important food reserve of many marine molluscs being needed for reproduction, growth and maintenance. Glycogen values were notably high during the non-breeding months especially during February
to May when they fluctuated between 33-35 and 52.22% of the dry
weight of the animal. From June to January the values were comparatively low. On the onset of the breeding season there was a perceivable fall in the glycogen content, probably owing to the initial mas8
spawning during June. After January the values were comparatively
high and reached the highest value for the year in March.
Some animals bore into timber for protection only but shipworms
digest and metabolize the cellulose of the wood into which they bore
and exploit it as a source of nourishment. This unusual ability is
attended with several morphological and physiological adaptations
associated with the new conditions of habitat and food involving
changes in metabolism necessitated by a diet that is chiefly carbohydrate (Dore and Miller, 1923 ; Boynton and Miller, 1927 ; Lane, 1955;
Nair, 195513, 1955~) 1956c, 1957b). The concentration of glycogen which
is even higher than that present in very " fat )' oysters has already
been reported by Lane et al. (1952) who report as high a value as
58.2%. Greenfield (1953) has shown that glycogen constitutes 30% of
the dry weight of Teredo. Scrutiny of individual values in our studies
shows that glycogen value in some specimens may reach 59.12% in