Bathymetric Distribution of Chaetognaths — Alvarino 
77 
syaiaw ni Hid3a 
Fig. 11 . Quantitative specific vertical distribution 
in the different Pacific water masses. 
tributional region, and their corresponding 
southernmost and northernmost edges of their 
respective domains overlap in deep waters (Fig. 
10), indicating a region of convergence in the 
respective distribution of the species — a con- 
vergence that partially coincides with the region 
of the hydrological convergence. S. hexaptera, 
S. bipunctata, S. enflata, K. subtilis, and P. draco 
(cosmopolitan species inhabiting the Pacific 
central waters) were recorded in the upper layers 
of that region of convergence, whereas at levels 
below 300 m S. gazeilae , S . pacifica , S. decipiens, 
S. macrocephala , E. fowleri, E. bathypelagica, 
E. hamata, and S. zetesios were recorded. The 
specimens of S', gazeilae recorded in this region 
were less than 20 mm long, at early Stage I of 
maturity. The boundary of the subtropical con- 
vergence also marks the northern limit of the 
distribution of S. tasmanica and S. planctonis . 
In other instances, when two masses of water 
pass one above the other, then the typical cold 
water species sink with the waters while the 
warm water species extend throughout the 
upper layers. 
S. tasmanica inhabits the upper 150 m in the 
Atlantic and in the southernmost part of the 
Indian Ocean (author, unpublished data). It 
enters the Pacific along with the subantarctic 
West Wind Drift, and its northward spread 
into the south Pacific stops at the region of the 
subtropical convergence. It extends westward, 
turning northward off the southern part of 
South America. This is demonstrated by the 
records of this species off Chile and at the 
southern part of Peru. It does not progress in 
the main Peru Current. The author’s data on the 
distribution of S. tasmanica in the Indian and 
Pacific oceans were obtained from samples col- 
lected by the Scripps Expeditions in both oceans 
(paper in preparation). Unfortunately, David 
(1958, 1959) did not explain if the serrato- 
dentata he recorded is S. serratodentata Krohn or 
S. tasmanica Thomson; although the locations of 
the records correspond to the distributional 
region of the latter. 
S. planctonis extends along the mid-depths 
of the Atlantic and Indian oceans, and enters 
the south Pacific with the subantarctic West 
Wind Drift, spreading to the subtropical con- 
vergence ( personal data ) . 
The greatest number of specimens for the 
