NOS. 620-621] THE HAWAIIAN CORAL REEFS 



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conforming to the substratum and having no definite 

 shape. The Calcarea are not uncommon in the littoral 

 region, especially in sheltered situations among rocks and 

 seaweed. These and the true horny sponges (Ceratosa) 

 have not been found below 2,700 ft. The sponges found 

 at the greatest oceanic depths are members of the Hexac- 

 iinell'ula and Chorisfifla of the Non-Calcarea. 



The Hawaiian sponges have few or no natural enemies, 

 and do not appear to be edible to fishes, crustaceans or 

 molluscs. Innumerable lowly forms, however, inhabit 

 their tissues, for shelter, if not for food. The interior 

 of any one of our common reef sponges is almost sure to 

 be found teeming with minute crustaceans, annelids, mol- 

 luscs and other invertebrates. 



None of the Hawaiian species have been utilized com- 

 mercially and no serious attempts have been made to in- 



