Bathymetric Distribution of Chaetognaths — AlvARINO 
79 
TABLE 3 
Ontogenic Vertical Distribution of S. gazellae 
LATITUDE S 
DEPTH 
(meters) 
MAXIMUM SIZE 
(millimeters) 
MacMurdo Sound (77°) 
7,10,72 
90 
46° 
140 
40 
283 
50 
346 
60 
42° 
283 
40 
400 
45 
11 the southern part of the subarctic waters is 
called the transition area. 
S. pseudoserratodentata and S. bierii are typ- 
ical of the northeast Pacific central waters; and 
5’. lyra of the northwest central waters, mainly 
the Kuroshio. Probably there are species typical 
of either southeast central and southwest central 
Pacific waters. Here are included our data from 
only the southeast central Pacific waters, because 
of the few data at hand from the southwest 
central Pacific region. 
3. Ontogenic distribution of the chaetognaths 
with depth 
Bigelow (1926), Huntsman (1919), and 
Russell (1931) found that the young of S. 
elegans appear in more superficial waters than 
do the adults. Fowler (1905) reported similar 
behavior for E. hamata. These records agree with 
my personal observations for the above species 
TABLE 4 
Ontogenic Latitudinal Distribution of 
S. scrippsae 
LATITUDE N 
MAXIMUM SIZE RANGE RECORDED 
(millimeters) 
46° 
60 
44° 
60 
42° 
60 
40° 
60 
38° 
46-50 
36° 
40-45 
34° 
40-45 
32° 
32-45 
30° 
28-45 
28° 
24-40 
26° 
15-36 
25° 
10-34 
24° 
10-20 
TABLE 5 
Ontogenic Latitudinal Distribution of 
S. gazellae 
LATITUDE S 
MAXIMUM SIZE RANGE RECORDED 
(millimeters) 
77° 
90 
64° 
85 
57° 
60 
54° 
50 
46° 
50 
44° 
50 
42° 
45 
40° 
25-45 
38° 
25-45 
36° 
30 
34°' 
30 
32° 
25 
30° 
20 
28° 
15-30 
26° 
20 
24° 
20 
22° 
20 
21° 
<20 
and for S. scrippsae, S. gazellae, S. zetesios, E. 
fowleri, S. minima, S. planctonis, and S. macro - 
cephala. 
The life history of these species might pos- 
sibly reflect the history of the phylum. It appears 
that the older genera and species have been 
relegated to the deep strata. The young genera 
and the young of each of the species are repre- 
sented by a large number of species and in- 
dividuals respectively per volumetric unit of 
water; while the old genera and species have 
fewer species and individuals respectively, in 
those parameters. 
The movement of the adults to deep layers 
could also be related to increase in weight of the 
individuals, associated with ripening of the sex- 
ual products. Further observations on this type 
of behavior might show if the Chaetognatha 
respond to a change in density like Daphnia 
pulex (Eyden, 1923), which decreases in spe- 
cific gravity when emptying its brood pouch. A 
similar regulation in pelagic fishes has been 
observed by several authors. 
A size stratification is usually found; some- 
times the mature specimens do not invade the 
deep strata. Mature S. scrippsae, 50-60 mm in 
length were found in the upper 140 m collec- 
tions, at 43° 46.5' N— 125° 08.5' W to 43° 
26.5' N— 125° 08.5' W. 
