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PACIFIC SCIENCE, Vol. XII, April, 1958 
however, was only 4; in the POFI collections, 
the maximum number of species at any one 
station was 9, more than twice the maximum 
number from the Barrier Reef. 
In summary, then, bearing in mind the 
difficulties of quantitative comparisons, the 
chief differences between the Salpidae of the 
Great Barrier Reef lagoon and of the central 
Pacific Ocean, based on limited captures, are 
as follows: (1) the numbers of species found 
are much fewer as a whole in the Great Barrier 
Reef than in the central Pacific; (2) the maxi- 
mum numbers of species present at any one 
station are much fewer in the Barrier Reef 
than in the central Pacific; (3) the numbers of 
individuals at any one station are often much 
greater in the Barrier Reef than in the central 
Pacific; (4) salps are more highly sporadic in 
distribution in the Barrier Reef than in the 
central Pacific, even being entirely absent 
from many stations, whereas they are present 
in all the POFI collections; (5) the most nu- 
merous and frequently occurring species, T. 
democratica , is the same in the two areas, but 
the species ranking next numerically and in 
frequency of occurrence are entirely different. 
Species other than T. democratica found in the 
Barrier Reef lagoon are relatively sparse and 
infrequent in the central Pacific collections, 
while the ranking species, other than T. demo- 
cratica, of the central Pacific are wholly lack- 
ing from the Barrier Reef collections, although 
they occur offshore in the Australian region. 
These differences probably reflect chiefly the 
widely differing ecologic conditions between 
a neritic and an oceanic environment. 
DISTRIBUTION OF SALPS 
Geographic Distribution 
Almost all investigators of planktonic ani- 
mals have concurred with Giesbrecht’s ob- 
servation that, . . the epipelagic high- 
oceanic fauna may be divided into three main 
zoogeographical regions: a warm-water and 
a northern and a southern cold-water zone” 
(Ekman, 1953). This is true of the Salpidae 
except for the fact that there are no species 
confined to northern cold water. Therefore, 
it appears that water temperature is the pri- 
mary limiting factor in the distribution of 
salps. 
The majority of salps are cosmopolitan 
warm water plankters, although they may be 
carried into high latitudes from time to time. 
Only Ihlea magalhanica , Thalia longicauda , 
Helicosalpa komaii , and Cyclosalpa strongylen- 
teron have been reported as restricted to cer- 
tain oceanic regions. According to Apstein 
(1894, 1906) and Thompson (1948), I. magal- 
hanica is restricted to the cool waters of the 
southern hemisphere; this is also true of T. 
longicauda according to Apstein, but Sewell 
(1953) reported one specimen from the north- 
ern Arabian Sea. H. komaii has been reported 
only from Japan (Komai, 1932) and the 
central Pacific (Yount, 1954), and C. strongy- 
lenteron only from the eastern Pacific (Berner, 
1955), but both probably will be found to 
occur in the Indian and Atlantic oceans as 
well. Table 1 lists salp distribution by species 
as reported by Pacific investigators. 
The remaining species of salps have been 
reported from the Atlantic, Indian, and Pacific 
oceans, except for Ihlea punctata , which has 
not yet been found in the Indian Ocean 
although it probably occurs there. Even the 
continents of South America and Africa do 
not prevent the transport of salps from one 
ocean to another, inasmuch as Herdman 
(1888) reported lasis zonaria and Apstein 
(1906) listed Salpa maxima and S. fusiformis 
from the Straits of Magellan, and Apstein 
(1906) showed that S. maxima , S. fusiformis , 
Metcalfina hexagona , Thalia democratica , T. 
longicauda , Pegea confoederata , la. zonaria , and, 
of course, Ih . magalhanica had been captured 
at the region of the Cape of Good Hope or 
in more southerly waters. Salps are carried far 
into northern waters also (see Ihle, 1935), but 
probably cannot be carried alive into the 
Arctic Ocean. 
With the exception of the four species 
mentioned above, then, it can be stated that 
the Salpidae is a family of cosmopolitan 
