74 
PACIFIC SCIENCE, VoL XVIII, January 1964 
has in general an epiplanktonic distribution, it 
sinks to deeper levels in the southernmost part 
of the California Current and disappears in 
these sinking waters. In this case, the distribu- 
tion of S. scrippsae in the lowest levels of the 
epiplanktonic domain or in upper layers of the 
mesoplanktonic region is due to the geographical 
location that is related to the oceanic circulation. 
From station 25 southward (53° 32.5' N — 
163° 20.8' W to 35° 46.8' N— 130° 02.5' W) 
the waters in the upper 200 m are inhabited by 
several species of Sagitta (Fig. 7): S. elegans 
from 41° N northward (station 13), and S. 
scrippsae (outstanding as an "indicator” of the 
California Current) from 46° N southward; 
and, from 40° N southward, also were present 
S. bierii, S. pacifica, S. pseudoserratodentata, S. 
bipunctata, S. hexaptera, S. enflata, K. subtilis, 
plus 10 other species that populate the low 
latitudinal regions of the California waters. In 
this section (Fig. 7) can be observed the pro- 
gressive sinking of E. hamata toward the low 
latitudes, and the stratification of S. decipiens, 
S. zetesios, and 5*. macro cephala (see also Fig. 9). 
S. decipiens extends in the Pacific from the 
southern boundary of the subarctic waters to 
the subtropical convergence in the southern 
hemisphere. It populates the mesoplanktonic 
layers, and occasionally is found in the upper 
140 m hauls, in which case its occurrence is an 
evidence of upwelling in that particular loca- 
tion, confirmed in every case by the hydro- 
graphic data (Alvarino, in press a). 
S. zetesios extends in the Pacific from 46° 
N to 36° S, and S . planctonis from about 30° 
S southward. It appears from the author’s data 
that the first species is more abundant than the 
latter. 
S. macro cephala was observed from the Aleu- 
tian Trench region to 46° S in the Pacific (per- 
sonal data). 
The record of a particular species at greater 
depths than usual may be due to different fac- 
tors, as already explained. Therefore, the dif- 
ference is clear between truly deep water species 
like E. fowleri, midwater S. decipiens, S. macro- 
cep hala, and E. hamata (epiplanktonic in high 
latitudes, bathypelagic in low latitudes), or 5". 
S. elegans 
fljgfl S. elegans 
^ S. scrippsae 
central water 
species 
E. hamata 
y////^ S.zetes ios 
•CTy'- S. decipiens 
S. macrocephala 
Fig. 6. Profile Stations 44-54 of the Transpac Expedition (53° 40.8' N, 161° 55.5' E to 40° 34.5' N, 170° 
02.3' E). 
