Chaetognaths of the Arabian Sea
303
maximum observed density is in the SE part (2221 per std. haul). The whole of the
northern part of the Arabian Sea has low values for S. ferox. The SW monsoon period
sustains a 6 times higher population and an almost uniform value prevails along the
equatorial region. The NE monsoon period has moderately high values near and off
Somalia, and off the southern tip of the Indian peninsula. A single patch of high density
is present near the Equator at about 58° E during the NE monsoon period.
9. Sagitta hexaptera (d'ORBIGNY, 1843)
(Figs. 8a and 8b)
Even though this species is found in many of the samples, its numerical representation
is usually low. In the collections it ranges from 0 - 2.4%. This species is represented
300 3~'
N
10'
0'
S
10'
50'
sO"
60"
10'
E 80"30'
. . .
. . .
N
20'
• ' : • S
70'
E 80" 10'
Fig. 8 a. Geographical distribution of S. hexaptera during the SW monsoon
30' 30'
N
20'
10'
S
10'
10'
E 80"30'
N
50'
70'
Fig. 8 b. Geographical distribution of S. hexaptera during the NE monsoon