6 
PACIFIC SCIENCE, VoL VII, January, 1953 
varieties. Though he noted that the members 
of the family were largely limited to the upper 
littoral 2 one of the sea, four species of Syn- 
alpheus and eight species of Crangon were 
dredged from depths greater than 100 meters 
during the Siboga Expedition. Two species 
have been reported from tropical fresh -water 
lakes. 
Like most of the marine fauna of the Ha- 
waiian Archipelago, the crangonids belong to 
the Indo-Pacific faunal group and not to the 
Western American. Those species that are not 
endemic range southward and westward, in 
many instances as far as the Red Sea. Crangon 
ventrosa (Milne-Edwards) is the only excep- 
tion to this statement: its range extends from 
the Red Sea through Hawaii to the Gulf of 
California. 
In the present state of knowledge of Crus- 
tacea in the Pacific it is useless to speculate on 
the distributional patterns of the nonendemic 
species. There are too many islands and archi- 
pelagoes where no collecting of marine inver- 
tebrates has been done at all; on the few major 
islands where some collecting has been done, 
it was done usually in a random fashion, and 
the lists of species cannot be regarded as even 
approaching completion. The few exceptions 
to this in the tropical Indo-Pacific region are 
the area around the mouth of the Red Sea, 
those portions of the Indian Ocean that were 
visited by J. Stanley Gardiner, and the portion 
of the southwestern Pacific visited by the Si- 
boga Expedition. It is likely that the report on 
the Bikini collections, now in preparation by 
Fenner A. Chace, Jr., of the United States Na- 
tional Museum, will add another area. But 
whether the range of a species extends from 
Hawaii to the Marianas or to the Marquesas 
or to New Caledonia is not known. 
Without the knowledge of the geographic 
range of the species, speculation on paths of 
distribution would be without basis. As the 
adults are bottom dwellers, and as the larvae 
are planktonic, it is safe to assume that most 
of the species that reached Hawaii were carried 
here as larvae. However, with the preponder- 
ance of the currents in this portion of the 
Pacific flowing from Hawaii toward the west- 
ern Pacific, it is difficult to understand how 
these larvae, without any marked powers of 
locomotion, were able to reach Hawaii from 
the closest island groups, over a thousand 
miles away. It is likely that they were carried 
here by fortuitous combinations of eddies and 
temporary shifts in the superficial currents in 
changing weather conditions. 
It is likewise fruitless to speculate on the 
number of endemic species. According to the 
present records 19 of the 44 species recorded 
from these islands, or some 45 per cent, are 
known only from the Hawaiian Archipelago. 
However, no one knows how many of these 
species may occur at Johnston Island or Can- 
ton Island or in Tahiti or Samoa; no one 
knows how many of these species may reach 
to the northern Marianas where conditions 
somewhat similar to those in Hawaii exist. It 
is to be expected that the isolated position of 
Hawaii would produce some speciation, but 
how much cannot yet be determined. 
ECOLOGY 
In Hawaii the members of the family seem 
to be confined largely, if not exclusively, to 
the eulittoral zone, which is deeper in tropical 
than in temperate waters. Many of the species 
are found exclusively in the shallow water of 
reef flats and in waters less than 50 feet deep 
at the outer side of the reef; a few have never 
been collected except on the reef flat itself, 
where at low tide the water varies from only a 
few inches to several feet in depth. The spe- 
cies inhabiting the more shallow waters are 
found in five types of habitats: in dead corals, 
where they live in cracks, folds, old worm 
holes, or even in tubes of algae which they 
construct for themselves; in living coral heads, 
among the branches of the coral; in sandy or 
muddy portions of the inner reef and of bays, 
where they hide about the bases of rocks and 
partially buried objects; in the dense growth 
of algae found on exposed wave-beaten 
coasts; and commensally with sponges and 
