326
V. R. NAIR and T. S. S. RAo:
is flowing on both sides. The western side of Kalpeni showed a higher density, the
maximum was observed at station 65 and it was due to patches of S. enflata, S. neglecta
and S. pacifica. The eastern side of Kavaratti where a greater abundance of chaetognaths
was found, and the western side of Kalpeni are the same part of the ocean surrounding
these atolls. The number of chaetognaths is reduced in the Kalpeni lagoon, but not as
drastically as in the Kavaratti lagoon. Relatively large swarms were found at stations
62, 57, 58 and 59, suggesting that occasionally rather undisturbed parcels of water
penetrate the lagoon, either over the reef or through some incoming channel. A similar
but much smaller patch was found in the Kavaratti lagoon at station 44.
III. Discussion
DONCASTER (1903) described the chaetognaths in the Laccadive and Maldive Archipelago based on the collections made in the years 1899 and 1900. He reported 15 species,
of which the validity of only 11 was accepted (ALVARINO, 1964). All the species recorded
by DONCASTER were present in the material studied except S. septata. S. bipunctata and
S. angulata are new records for the Laccadive area. Only 2 specimens of K. pacifica were
present in DONCASTER'S collections, whereas in the present material it was common. In
DONCASTER'S collections, S. regularis occured in small numbers and S. pulchra in moderate
numbers. The present work showed that, next to S. enflata, S. regularis was the most
abundant form at Kavaratti atoll, and that it was moderately common in the Kalpeni
atoll. S. pulchra was sparse in all the collections. SILAS and SRINIVASAN (1969) reported
on the occurrence of 14 species from the Laccadive Seas and off the west coast of India.
Their collections include the mesoplanktonic species S. decipiens and S. lyra and bathyplanktonic species Eukrohnia fowleri and E. minuta.
It is of interest to see how the species composition of chaetognaths in our collections
compares with that of the samples taken from the Laccadive Seas (between 08 0 45'09 0 09'N and 71 030' -74
0
30' E) during the HOE (1959-1965). Ten standard samples
(lOBe, 1969) collected by "Meteor" in February 1965 (4 samples), "Discovery" in May
1964 (1 sample), "Kistna" in August 1963 (1 sample) and "Varuna" in November 1963
(4 samples) are available. Of these, the "Varuna" and "Meteor" samples, like ours,
were taken during the NE monsoon. S. enflata was the dominant chaetognath in all these
samples. The other common forms occuring in the HOE samples were S. pacifica, Pterosagitta draco, S. bedoti and S. bipunctata in decreasing order of abundance. In the HOE
samples better representation of Pt. draco, S. bipunctata, S. hexaptera and S. pulchra
were noticed while S. neglecta, S. regularis and S. robusta were rare. Krohnitta subtilis
(GRASSI, 1881) was represented in these samples and is an addition to the list of species
from the Laccadive Seas.
The present collections include only epiplanktonic species except for Sp. angulata.
K. subtilis, Pt. draco, S. bipunctata, S. enflata and S. hexaptera are all cosmopolitan
forms of warm and temperate oceanic waters (ALVARINO, 1965). K. pacifica is also
widely distributed but only in the equatorial belts of the Atlantic, Pacific and Indian
Ocean (ALVARINO, 1965). S. bedoti, S. neglecta, S. ferox, S. pacifica, S. pulchra, S. regularis and S. robusta are Indo-Pacific forms. The presence of Sp. angulata, a bottom
dwelling species inside the lagoon at Kalpeni suggests that it breeds there and that it may
be a permanent inhabitant of the lagoon. Sp. angulata is a new record from the Arabian
Sea. Apart from the record of this species from the west of Penang Island (PATHANSALI,
V. R. NAIR and T. S. S. RAo:
is flowing on both sides. The western side of Kalpeni showed a higher density, the
maximum was observed at station 65 and it was due to patches of S. enflata, S. neglecta
and S. pacifica. The eastern side of Kavaratti where a greater abundance of chaetognaths
was found, and the western side of Kalpeni are the same part of the ocean surrounding
these atolls. The number of chaetognaths is reduced in the Kalpeni lagoon, but not as
drastically as in the Kavaratti lagoon. Relatively large swarms were found at stations
62, 57, 58 and 59, suggesting that occasionally rather undisturbed parcels of water
penetrate the lagoon, either over the reef or through some incoming channel. A similar
but much smaller patch was found in the Kavaratti lagoon at station 44.
III. Discussion
DONCASTER (1903) described the chaetognaths in the Laccadive and Maldive Archipelago based on the collections made in the years 1899 and 1900. He reported 15 species,
of which the validity of only 11 was accepted (ALVARINO, 1964). All the species recorded
by DONCASTER were present in the material studied except S. septata. S. bipunctata and
S. angulata are new records for the Laccadive area. Only 2 specimens of K. pacifica were
present in DONCASTER'S collections, whereas in the present material it was common. In
DONCASTER'S collections, S. regularis occured in small numbers and S. pulchra in moderate
numbers. The present work showed that, next to S. enflata, S. regularis was the most
abundant form at Kavaratti atoll, and that it was moderately common in the Kalpeni
atoll. S. pulchra was sparse in all the collections. SILAS and SRINIVASAN (1969) reported
on the occurrence of 14 species from the Laccadive Seas and off the west coast of India.
Their collections include the mesoplanktonic species S. decipiens and S. lyra and bathyplanktonic species Eukrohnia fowleri and E. minuta.
It is of interest to see how the species composition of chaetognaths in our collections
compares with that of the samples taken from the Laccadive Seas (between 08 0 45'09 0 09'N and 71 030' -74
0
30' E) during the HOE (1959-1965). Ten standard samples
(lOBe, 1969) collected by "Meteor" in February 1965 (4 samples), "Discovery" in May
1964 (1 sample), "Kistna" in August 1963 (1 sample) and "Varuna" in November 1963
(4 samples) are available. Of these, the "Varuna" and "Meteor" samples, like ours,
were taken during the NE monsoon. S. enflata was the dominant chaetognath in all these
samples. The other common forms occuring in the HOE samples were S. pacifica, Pterosagitta draco, S. bedoti and S. bipunctata in decreasing order of abundance. In the HOE
samples better representation of Pt. draco, S. bipunctata, S. hexaptera and S. pulchra
were noticed while S. neglecta, S. regularis and S. robusta were rare. Krohnitta subtilis
(GRASSI, 1881) was represented in these samples and is an addition to the list of species
from the Laccadive Seas.
The present collections include only epiplanktonic species except for Sp. angulata.
K. subtilis, Pt. draco, S. bipunctata, S. enflata and S. hexaptera are all cosmopolitan
forms of warm and temperate oceanic waters (ALVARINO, 1965). K. pacifica is also
widely distributed but only in the equatorial belts of the Atlantic, Pacific and Indian
Ocean (ALVARINO, 1965). S. bedoti, S. neglecta, S. ferox, S. pacifica, S. pulchra, S. regularis and S. robusta are Indo-Pacific forms. The presence of Sp. angulata, a bottom
dwelling species inside the lagoon at Kalpeni suggests that it breeds there and that it may
be a permanent inhabitant of the lagoon. Sp. angulata is a new record from the Arabian
Sea. Apart from the record of this species from the west of Penang Island (PATHANSALI,