GULF OF MEXICO 



445 



The littoral barnacles with the widest dis- 

 tribiitioii in the Gulf are Balanvft ehurneu,'^, B. 

 amph'itrite nweiifi, and Chthamalus fraffilis. In 

 the Florida Keys the common intertidal barnacles 

 of the rocky shore are Chthamalus steUatufi an- 

 guxtitergum and Tetraclita squamosa stalactifera, 

 with the Chthamalus occurring at the highest 

 level of the midlittoral zone and the Tetraclita 

 at a slightly lower level but overlapping the 

 Chthamalus (Stephenson and Stephenson, 1950). 

 The distribution of these two species in the Florida 

 Keys is peculiar; both varied from absent to 

 abundant on the oceanic sides of the keys and 

 from absent to fairly common on the Florida Bay 

 side, and no north-to-south effect could be 

 demonstrated. T. s. stalactifera and C. s. an- 

 gu-stitergum have not been reported from western 

 Florida, although they might be expected to 

 occur in the southern part. 



B. eburneiis and B. a. nweus range from the 

 Florida Keys, where Stephenson and Stephenson 

 (1950) found them commonly on walls, wharfs, 

 and piles but never on the rocky platforms, to the 

 Texas shore. The vertical range for both species 

 is from a little above the low tide line to, at least, 

 25 fathoms. They are found oftener on wood or 

 shells than on rock, and both are able to live in 

 brackish water. 



Chthamalus Jragilis also ranges from the Florida 

 Keys, where it is apparently rare, to the Texas 

 shore. It is probably commoner on the northern 

 shores of the Gulf than is indicated by the records, 

 as members of this genus are often overlooked by 

 collectors because of the small size and incon- 

 spicuous form. The vertical distribution is un- 

 known for the Gulf, but it occupies a high level 

 of the intertidal zone in other parts of its range. 



Below low tide line the most widespread bar- 

 nacles are B. galeatus, situated on gorgonians, and 

 B. calidus on shells of all kinds and on dead 

 echinoderms. According to Hedgpeth (personal 

 communications), B. galeatus is commonly found 

 on stems of gorgonians which have drifted onto 

 the Texas beach. 



The other species of Balanus occurring in the 

 littoral zone have been found at only one or two 

 localities so one can only guess at their distribu- 

 tion. B. improvisus will probably be found along 

 the northern part of the Gulf, wherever a suitable 



substratum (wood, shells, and rock) is found, as 

 this species, like B. eburneus and B. a. nweus, 

 is partial to brackish water. In other areas the 

 vertical distribution of this species is from the low 

 tide line to 150 meters. B. trigonus, in other parts 

 of its wide range, occurs from 1 to 3,000 meters on 

 shells, crabs, and sponges. These two species, 

 as well as B. eburneus and B. a. niveus, are im- 

 portant fouling organisms in other areas, bat what 

 part they play in the fouling of ships in the Gulf 

 is unknown. 



The barnacles, B. declivis, B. stultus, and Acasta 

 cyathus, which live in sponges have been reported 

 from the southern part of the Gulf, but an ex- 

 amination of the sponges of other parts of the Gulf 

 will no doubt extend the distribution. 



In addition to the barnacle-gorgonian and 

 barnacle-sponge associations mentioned above, 

 three other barnacle-associations occur in the 

 Gulf. The barnacle-coral association is practically 

 unknown, as apparently coral has not been ex- 

 amined for barnacles. One species of Pyrgoma has 

 been reported by Pilsbry (1931) in coral. Of 

 the turtle barnacles, Chelnnobia testudinaria is 

 widely distributed in the Gulf as is probably 

 Platylepas hexastylos (a subspecies has been found 

 on a fish in western Florida by Pilsbry, 1916). 

 A subspecies of C. manati and Stomatolepas 

 praegustator are known from only one locality in 

 the Gulf. 



The barnacles associated with crabs of the Gulf 

 may be externally on the carapace and internally 

 on the braiichiae. Chelonobia patula and three 

 species of PoecUasma, both of which are mainly 

 on crabs, in addition to four species of Balanus 

 {a. niveus, improvisus, eburneus, and trigonus) 

 may be found on the carapace. Three species of 

 Octolasmis occur on the branchiae. The shallow 

 water crab, Callinectes sapidus, is the host of at 

 least the first three species of Balanus enumerated 

 above, C. patula, Octolasmis lowei, B. trigonus, 

 PoecUasma, and all three species of Octolasmis are 

 associated with deep water crabs or palinurids. 



Neither the pelagic nor the deep water barnacles 

 are of any assistance in determining the relation- 

 ship to other faunal areas. The three species of 

 the pelagic genus Lepas which occur in the Gulf 

 are nearly cosmopolitan. Conversely, the species 

 of the deep water genera, Scalpellum and Verruca, 



