4.6
Chaetognaths of the Arabian Sea
v. R. NAIR and T. S. S. RAO
During the HOE (1959 -1965) the Indian Ocean Biological Centre (IOBC) received
1927 zooplankton samples, of which 1548 are standard ones (IOBC, 1969). Of these,
614 samples belong to the area extending from 10 ° S to 25 ° N lat. between 20
0
E and
80
0
E long. The chaetognaths identified from these 614 samples form the basis of the
present study. The figures given refer to catch per unit standard haul.
I. Distribution of Species
A total of 19 species belonging to 4 genera Eukrohnia, Krohnitta, Pterosagitta, and
Sagitta are present in the collections analysed.
Table 1 represents the total counts, percentage and maximum density of the different
species. The seasonal differences for the different species are shown in Table 2.
Table 1. Total counts, percentage and maximum density of the different chaetognaths species from
the II 0 E collections
Species
Total abundance
Range of
Maximum observed density
Number Percent- abundance
(No. per std. haul)
age
per5°Sq.
SWmonsoon
NEmonsoon
%
E. fowleri
7 negligible negligible
4
(Laccadive Sea)
K. pacifica
10847
1.0
0- 5.7
250
425
(near Kenya)
(Red Sea)
K.subtilis
3780
0.3
0- 3.1
400
100
(off Somalia)
(off Ceylon)
Pt. draco
48319
5.1
0-19.1
1940
810
(off Somalia)
(Gulf of Aden)
S. bedoti
94709
8.3
0-35.8
4160
2960
(off Somalia)
(near Kenya coast)
S. bipunctata
48815
4.3
0- 23.6
3620
735
(off Somalia)
(off Arabia towards north)
S. bombayensis
2 negligible negligible
2
(off the northwest coast
of India)
S. decipiens
26 negligible negligible
16
(off South Arabia)
S. enflata
697810 61.0
31.6-86.3
9000
18585
(off Somalia)
(Red Sea)
S. ferox
23654
2.1
0-31.0
2221
820
(South eastern
(off Somalia)
part at
lO o S-75°E)
Chaetognaths of the Arabian Sea
v. R. NAIR and T. S. S. RAO
During the HOE (1959 -1965) the Indian Ocean Biological Centre (IOBC) received
1927 zooplankton samples, of which 1548 are standard ones (IOBC, 1969). Of these,
614 samples belong to the area extending from 10 ° S to 25 ° N lat. between 20
0
E and
80
0
E long. The chaetognaths identified from these 614 samples form the basis of the
present study. The figures given refer to catch per unit standard haul.
I. Distribution of Species
A total of 19 species belonging to 4 genera Eukrohnia, Krohnitta, Pterosagitta, and
Sagitta are present in the collections analysed.
Table 1 represents the total counts, percentage and maximum density of the different
species. The seasonal differences for the different species are shown in Table 2.
Table 1. Total counts, percentage and maximum density of the different chaetognaths species from
the II 0 E collections
Species
Total abundance
Range of
Maximum observed density
Number Percent- abundance
(No. per std. haul)
age
per5°Sq.
SWmonsoon
NEmonsoon
%
E. fowleri
7 negligible negligible
4
(Laccadive Sea)
K. pacifica
10847
1.0
0- 5.7
250
425
(near Kenya)
(Red Sea)
K.subtilis
3780
0.3
0- 3.1
400
100
(off Somalia)
(off Ceylon)
Pt. draco
48319
5.1
0-19.1
1940
810
(off Somalia)
(Gulf of Aden)
S. bedoti
94709
8.3
0-35.8
4160
2960
(off Somalia)
(near Kenya coast)
S. bipunctata
48815
4.3
0- 23.6
3620
735
(off Somalia)
(off Arabia towards north)
S. bombayensis
2 negligible negligible
2
(off the northwest coast
of India)
S. decipiens
26 negligible negligible
16
(off South Arabia)
S. enflata
697810 61.0
31.6-86.3
9000
18585
(off Somalia)
(Red Sea)
S. ferox
23654
2.1
0-31.0
2221
820
(South eastern
(off Somalia)
part at
lO o S-75°E)