THE PORIFERA OF THE GULF OF MEXICO 



By J. 0- TiERNEY, Marine Laboratory, University of Miami 



Sponges are one of the dominant sessile inverte- 

 brate groups in the Gulf of Mexico: they extend 

 from the intertidal zone down to the deepest 

 parts of the basin, and almost all of the firm or 

 rocky sections of the bottom provide attachment 

 for them. 



Members of the class Hyalospongea (Hexacti- 

 nellidea) are, almost without exception, limited to 

 the deeper waters of the Gulf beyond the 100- 

 fathoni curve. These sponges possess siliceous 

 spicules in which (typically) six rays radiate from 

 a central point; frequently, the spicules are fused 

 together forming a basket-like skeleton. Spongin 

 is never present in this group. 



In contrast to the Hyalospongea, representa- 

 tives of the class Calcispongea are seldom, if 

 ever, found in deep water. These sponges, unique 

 in having spicules of calcareous material, are usu- 

 alh' restricted to shallow water. They are not 

 conspicuous; typically, they are encrusting forms 

 or tubiform in shape but only a few centimeters in 

 height. 



The major sponge group in the Gulf of Mexico, 

 both from number of genera and from the range 

 of distribution, is the class Demospongea. Pos- 

 sessing more or less spongin, and when spicules 

 are present having unfused spicules of siliceous 

 material, these sponges occur throughout the Gulf 

 extending from the shallow coastal waters down 

 to the deepest ofF-shore sections of the basin. 



The sponge bars or reefs of the eastern Gulf are 

 quite typical of the habitat and ecology of the 

 sponges in shallow to moderate depths. These 

 so-called reefs are sections of rocky outcroppings 

 that are elevated a few inches to a few feet above 

 the general bottom profile. They are more or less 

 densely covered with commercial and non-com- 

 mercial sponges, coral (usually Oculina), and 

 Alcyonaria. The other bottom-dwelling marine 

 groups (such as mollusks, annelids, Crustacea, 

 ascidians) are associated with the dominant 



• Contribution No. lO.'i. Marine Laboratory, University of Miami. 

 259534 O— 54 18 



groups. The floor of the Gulf between the bars 

 is sparsely populated. The majority of the ani- 

 mals and plants are concentrated on the rocky 

 ledges and outcroppings. 



The most abundant sponges on these reefs are 

 of several genera representing most of the orders 

 of the class Demospongea. Several species of 

 Ircinia are quite common as are Verongia, Sphecio- 

 spongia, and several Axinellid and Ancorinid 

 sponges; Cliona is very abundant, boring into 

 molhiscan shells, coral, and the rock itself. The 

 sponge population is rich both in variety and in 

 number of individuals; for this reason no attempt 

 is made to discuss it in taxonomic detail in this 

 resume. 



Some of the sponges of the Gulf are of world- 

 wide distribution, i. e., Dysidea fragilis, while 

 others are typically West Indian, and a few are 

 probably restricted to the Gulf. The West Indian 

 sponge fauna may be a single regional population 

 with only minor locational differences. Water 

 currents of the Caribbean, the Gulf, and the 

 southern portion of the western Atlantic off Florida 

 and the Bahama Islands have been shown to 

 to carry a sponge disease from one point to many 

 others in this region; it is therefore permissible to 

 suggest that the same currents would be equally 

 effective in distributing sponge larvae. 



The commercial sponges of Florida, the Ba- 

 hamas, Cuba, and British Honduras are all quite 

 similar: the sheepswool sponge, Hippiospongia 

 lachne, is the most valuable sponge now available 

 for the market. Reef, glove, yellow, and grass 

 sponges, all members of the genus Spongia, are of 

 less value and are therefore less eagerly sought by 

 the sponge fishermen. 



Two methods, in general, are used in the West 

 Indian region for the collection of commercial 

 sponges. Hooking is practiced in waters of less 

 than 7 or 8 fathoms throughout the entire zone, 

 and light-weight, full diving rigs are used in the 

 Gulf of Mexico in depths of less than 20 fathoms. 



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