BIOLOGY OF THE COMMERCIAL SPONGES' 



By F. G. Walton Smith, Marine Laboratory, University of Miami 



All commercial sponges of the Gulf of Mexico 

 belong to the family Spongiidae. They are char- 

 acterized bj' a lack of spicules and by the presence 

 of a skeleton consisting of a network of anastomo- 

 sing spongin fibers. The canal system is of the 

 leucon type. Subdermal cavities which act as 

 vestibules to either the incurrent or excurrent 

 canal systems, or both, are present to a varying 

 degree and are particularly noticeable in the 

 velvet sponge, Hippiospongia gossypina. 



The external form is roughly subspherical in 

 the case of sheepswool sponge, Hippiospongia 

 lachne, the yellow sponge, Spongia zimocca ss. 

 harhara, hard head, Spongia officinalis ss. dura, 

 and the velvet sponge. The grass sponge, 

 Spongia graminea, may be in the form of an up- 

 right cylinder, somewhat wider and slightly con- 

 cave in the upper surface. Large sponges of this 

 type in the Gulf of Mexico waters, however, are 

 usually cup-shaped. Other sponges sometimes 

 found are the reef sponge, Spongia officinalis ss. 

 ohliqua. These are small sponges somewhat 

 cylindrical in general shape but with lobes ter- 

 minated by oscula on the upper surface. The 

 glove sponge, assigned to Spongia graminea, is 

 stoutly columnar with fluted sides. The shape 

 and appearance varies considerably according to 

 the environment. Detailed descriptions of the 

 various forms are given by Moore (1910). 



The outer surface is covered with a thin but 

 tough skin which is usually dense black in color. 

 Portions of the sponge buried in mud and the 

 basal portions are more or less deficient in pig- 

 ment. The flagellated chambers of all commer- 

 cial sponges are small in size and are pyriform or 

 subspherical in shape with a diameter of no more 

 than 0.03 mm. The choanocA'tes are approxi- 

 mately 4 microns in cross section. 



Spongin fiber has been auahzed by Block and 

 Boiling (1939). It is composed of keratin, an in- 

 ert product related to the collogens. Keratin 



' Contribution No. 109 from the Marine Laboratory, University of Miami. 



contains iodine and the amino acids Ij'sine, argi- 

 nine, cystine, phenylalanine, and glycine. Very 

 small amounts of histidine and tyrosine are also 

 present. 



Sexual reproduction takes place at all times of 

 the year but most intensively during April, May, 

 and June, and in November and December, ac- 

 cording to observations made by the author in 

 the Bahamas Islands. Eggs are found in sponges 

 as small as 2 inches in diameter. They are im- 

 bedded in the tissues between the flagellated 

 chambers and are about 0.25 cm. in diameter. 

 In their early stages of development they are 

 white but become a dark olive green as the 

 embryo develops. Whereas eggs are easily visible 

 to the naked eye when a sponge is sliced open, the 

 spermatozoa are not recognizable except under 

 the microscope. No information is available as 

 to whether spermatozoa and eggs are produced by 

 the same sponge at different times. Since they 

 have not been observed in the same sponge at the 

 same time, it is possible that commercial sponges 

 are dioecious. 



Toward the end of embryonic development the 

 embryo develops a circle of cilia at the anterior, 

 less strongly pigmented end. The larva then 

 escapes into the excurrent canal system and 

 thence to the exterior. Further development has 

 not been observed in detail in commercial sponges. 



There is little definite evidence as to the food 

 of sponges. Ingestion of carmine particles by the 

 choanocytes has been observed by Bidder (1896) 

 and subsequent authors, in the non-commercial 

 sponges. According to Bidder, the flagellated 

 cells of Sycon raphanus, which are 5 microns in 

 width, contain rod-shaped bodies similar to bacilli 

 between 1 and 2 microns long. Pourbaix (1931) 

 describes the transference of carmine grains from 

 choanocytes to adjacent amoebocytes. PourbaLx 

 (1931) also states that after feeding with carmine, 

 granules of this appeared in the amoebocytes of 

 the Tunisian commercial sponge. 



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