Chaetognaths of the Arabian Sea
313
Table 4. Environmental data for the chaetognaths described as meso- and bathyplanktonic forms
Species
Previous data
Present data
Depth from which recorded in the
Temperature Salinity
Tempera- Salinity
Indian Ocean
DC
S'Yoo
ture DC S%o
E. fowleri
13.4-14.5
34.65
13.99
35.23
600 and below to 1300 m.
(OWRE,
(SUND,
16.51
34.90
(SILAS and SRINIVASAN, 1969)
1960)
1961 )
Mainly below 450 m
(BURFIELD and HARVEY, 1926)
S. decipiens 8.9-18.0
34.4-34.9
15.14
35.54
Maximum at 405
(SUND,
(SUND,
13.48
34.99
Spread at 720 m
1961)
1961)
(BURFIELD and HARVEY, 1926)
S.lyra
14.7-24.2 35.8-36.8
15.51
35.41
225,270
(PIERCE and (PIERCE and
(BURFIELD and HARVEY, 1926)
WAss,1962) WASS, [962)
100 or 200 to the surface
(TOKIOKA, 1956)
0-50m
(TSURAT, 1963)
300 and below to 1300 m
(SILAS and SRINIVASAN, 1969)
S. zetesios
12.4
34.6
16.05
35.85
(FAGETII,
(SUND,1961 )
1958)
18. Sagitta lyra (KROHN, 1853)
(Fig. 15)
Seven specimens were obtained from a single station near the mouth of the Gulf of
Aden (12 0 04' Nand 51 0 31' E) in Oct. 1963. The hydrographical data indicate upwelling at the time of collection. Comparatively cold water (22.88 0 C) was present at
40 m. The recorded temperature at 22 7 m was 13.6 0 C, salinity 35.6%0 and dissolved O 2
0.89 mll- 1 (Arabian Sea Subsurface Water mass).
19. Sagitta zetesios (FOWLER, 1905)
(Fig. 15)
Six specimens of this species were found in a sample taken in the North Arabian Sea
(19 0 17'N lat. and 62" 29'E long.) in November 1963. The data show the presence of
upwelling waters at the time of sampling. Temperature at 40 m was 23.4 0 C and O2
content was low from 75 m (0.70 mil - I) downwards. The temperature and salinity at
199 m were 16.05 0 C and 35.85%0 respectively while dissolved O2 content was 0.40 mll- J
(Arabian Sea Subsurface Water).
II. Discussion
The collection includes 15 epiplanktonic species, 3 mesoplanktonic and 1 bathyplanktonic species, the 2 latter groups being very rare and represented by a few stray individuals. S. enflata is the dominant species in this area, constituting 32 - 86% of the total
chaetognaths. S. pacifica, S. bedoti, Pt. draco, S. bipunctata and S. regularis are the other
313
Table 4. Environmental data for the chaetognaths described as meso- and bathyplanktonic forms
Species
Previous data
Present data
Depth from which recorded in the
Temperature Salinity
Tempera- Salinity
Indian Ocean
DC
S'Yoo
ture DC S%o
E. fowleri
13.4-14.5
34.65
13.99
35.23
600 and below to 1300 m.
(OWRE,
(SUND,
16.51
34.90
(SILAS and SRINIVASAN, 1969)
1960)
1961 )
Mainly below 450 m
(BURFIELD and HARVEY, 1926)
S. decipiens 8.9-18.0
34.4-34.9
15.14
35.54
Maximum at 405
(SUND,
(SUND,
13.48
34.99
Spread at 720 m
1961)
1961)
(BURFIELD and HARVEY, 1926)
S.lyra
14.7-24.2 35.8-36.8
15.51
35.41
225,270
(PIERCE and (PIERCE and
(BURFIELD and HARVEY, 1926)
WAss,1962) WASS, [962)
100 or 200 to the surface
(TOKIOKA, 1956)
0-50m
(TSURAT, 1963)
300 and below to 1300 m
(SILAS and SRINIVASAN, 1969)
S. zetesios
12.4
34.6
16.05
35.85
(FAGETII,
(SUND,1961 )
1958)
18. Sagitta lyra (KROHN, 1853)
(Fig. 15)
Seven specimens were obtained from a single station near the mouth of the Gulf of
Aden (12 0 04' Nand 51 0 31' E) in Oct. 1963. The hydrographical data indicate upwelling at the time of collection. Comparatively cold water (22.88 0 C) was present at
40 m. The recorded temperature at 22 7 m was 13.6 0 C, salinity 35.6%0 and dissolved O 2
0.89 mll- 1 (Arabian Sea Subsurface Water mass).
19. Sagitta zetesios (FOWLER, 1905)
(Fig. 15)
Six specimens of this species were found in a sample taken in the North Arabian Sea
(19 0 17'N lat. and 62" 29'E long.) in November 1963. The data show the presence of
upwelling waters at the time of sampling. Temperature at 40 m was 23.4 0 C and O2
content was low from 75 m (0.70 mil - I) downwards. The temperature and salinity at
199 m were 16.05 0 C and 35.85%0 respectively while dissolved O2 content was 0.40 mll- J
(Arabian Sea Subsurface Water).
II. Discussion
The collection includes 15 epiplanktonic species, 3 mesoplanktonic and 1 bathyplanktonic species, the 2 latter groups being very rare and represented by a few stray individuals. S. enflata is the dominant species in this area, constituting 32 - 86% of the total
chaetognaths. S. pacifica, S. bedoti, Pt. draco, S. bipunctata and S. regularis are the other