THE SEAWEEDS OF HAWAII 
475 
lava are scattered here and there along the beach and in the shallow 
water. These rocks are horizontally banded with hydroid and algal 
colonies. Further out there are numerous ''pockets" or cup-like 
depressions in the lagoon floor. These vary in size from a meter in 
depth and diameter to large pools five or ten meters in depth and 
diameter. These pockets are easily marked by the darker tint of 
their water. In them live a variety of organisms that prefer these 
shadowy havens to the exposure of the shallows or the surf-smitten 
outer reef. 
The next zone is one of deeper water, where wading is no longer 
possible. The sunny, transparent water is three to ten meters deep, 
but becomes shallower as the edge of the reef is approached. On the 
outer rim pound eternally the long rollers of the Pacific, with iridescent 
spray haze and the deep-toned roar of the surf. Beyond this rim the 
reef drops abruptly in the abyssal waters of the Pacific. These five 
zones — shallows, rocks, pools, rim, and outer face of reef — each have 
distinctive combinations of ecologic factors, and each supports a 
distinctive flora and fauna. 
Several hundred species of marine algae, exclusive of microscopic 
and unicellular forms, have been collected in Hawaiian waters. These 
represent a wide range of genera — green, blue-green, brown and red 
groups — and of habitats. Many species are as yet undescribed and 
await taxonomic investigation. Among the better represented genera 
are: Codium, Padina, Halimeda, Dictyota, Turbinaria, Ectocarpus, 
Enteromorpha, Bryopsis, Caulerpa, Laurencia, Gelidium, Griffithsia, 
Haliseris, Sargassum, Hypnea, Ulva, Polysiphonia, Porphyra, Hydro- 
dictyon, Gracilaria and Ceramium. 
Of great significance as reef builders are the coralline algae or 
nullipores. There are a number of species that inhabit the shallow 
waters, forming beautiful purple and lavender incrustations; others 
occur at considerable depths. The Hawaiian reefs, like those of other 
regions, undoubtedly owe a considerable proportion of their structure 
to plant depositions. 
Many of the marine algae occupied places of prominence in the 
dietary of the ancient Hawaiians, and still constitute a staple in the 
native food. The villages, like those of other parts of Polynesia, 
were almost universally situated on or near the seashore. The ancient 
Hawaiians were preeminently a maritime people. They were inti- 
mately familiar with the products of the sea. A large part of the 
