Commensal Algæ and Reef Corals

Abstract

DR. YONGE has directed my attention to an error in my recent paper on coral reefs (Bull. Mus. Comp. Zool., 71, 6; 1930), the origin of which is of no importance. The statement is that Millepora and reef-building Alcyonaria do not possess commensal algæ. This is quite contrary to fact—for Prof. Hickson showed me them in Millepora upwards of forty years ago—and also to the main argument in my course of lectures delivered at the Lowell Institute at Boston. I had decalcified pieces of more than forty colonies of these various forms from surface reefs in the Indian and Pacific oceans and found that zoochlorellæ were present in all. They included Millepora and Heliopora, which in certain positions may be as important builders as reef corals, and the soft corals (Sarcophytum, Sclerophytum, and Lobophytum) so widely distributed on lagoon and protected reefs.