Gulf of Mexico Origin, Waters, and Biota: Volume I, Biodiversity

67. Entoprocta of the Gulf of Mexico

Entoprocts (sometimes called kamptozoans) are predominantly marine (one species is limnic), sessile or colonial , benthic animals; their range extends from shallow water to several hundred meters, but the group is generally poorly studied. Each zooid consists of a body with a horseshoe of tentacles and a stalk; in colonial species, the zooids are budded from a creeping stolon; zooids vary in size from about 0.2 mm to about 5 mm (Ruppert, Fox, and Barnes 2004). Both adult and larval entoprocts are filter feeders with a downstream-collecting ciliary system working after the catch-up principle (Riisgård, Nielsen, and Larsen 2000). The solitary species are apparently protandric, whereas the colonial species may comprise hermaphroditic zooids, or colonies may consist of male and female zooids or of hermaphroditic zooids, according to species (Wasson 1997). The life cycle includes a freeswimming , trochophora-type larva that may be lecithotrophic and settle after a few hours or planktotrophic with a long planktonic phase (Nielsen 1971). The entoprocts are spiralians, as shown by their embryology and larval type, but their phylogenetic position is much debated (Nielsen 2001). Entoprocts are an understudied group of small organisms that are often overlooked. Many of the solitary species are commensals, especially of annelids, sponges, and sipunculans; some of the species occur on the inner side of the polychaetes’ tubes or in the water canals of sponges, so they have to be searched for specifically. The colonial species are locally abundant on stones, algae, and hydroids. New species are discovered almost every time a new locality is studied. An example of local diversity is the Danish waters, where more than 25 species have now been recorded (Nielsen 1989). Entoprocta were not included in the original Bulletin 89, and the only published record appears to be of Pedicellina cernua and Barentsia discreta from Tortugas Island (Osburn 1914). Several additional species will probably be discovered if entoprocts are specifically searched for. A number of solitary species have been described from Miami, Florida (Nielsen 1966a, b). Abbreviations Abbreviations in the Habitat-Biology column of the checklist include ben = benthic; bns = bay and nearshore; and hsb = hard substrate. 1143 67 Entoprocta of the Gulf of Mexico Claus Nielsen  Entoprocta. After Osburn 1912. 1144 ~ Entoprocta 6. Osburn, R. C. 1914. The Bryozoa of the Tortugas Islands, Florida. Publications of the Carnegie Institution of Washington 182: 181–222. 7. Riisgård, H. U., C. Nielsen, and P. S. Larsen. 2000. Downstream collecting in ciliary suspension feeders: the catch-up principle. Marine Ecology Progress Series 207: 33–51. 8. Ruppert, E. E., R. S. Fox, and R. D. Barnes. 2004. Invertebrate Zoology: A Functional Evolutionary Approach (7th ed. of R. D. Barnes’ Invertebrate Zoology). Brooks/Cole, Belmont, California. 9. Wasson, K. 1997. Sexual modes in the colonial kamptozoan genus Barentsia. Biological Bulletin, Woods Hole 193: 163–170. References 1. Nielsen, C. 1966a. On the life-cycle of some Loxosomatidae (Entoprocta). Ophelia 3: 221–247. 2. Nielsen, C. 1966b. Some Loxosomatidae (Entoprocta) from the Atlantic Coast of the United States. Ophelia 3: 249–275. 3. Nielsen, C. 1971. Entoproct life-cycles and the entoproct /ectoproct relationship. Ophelia 9: 209–341. 4. Nielsen, C. 1989. Entoprocta. Synopses of the British Fauna, New Series 41: 1–131. 5. Nielsen, C. 2001. Animal Evolution: Interrelationships of the Living Phyla, 2nd ed. Oxford University Press, Oxford, U.K. 563 pp. Submitted: March 2006 Accepted: September 2006 Nielsen ~ 1145 Taxonomic summary for entoprocts of the Gulf of Mexico. Group Total species Number endemic species Number nonindigenous species Entoprocta 2 0 0 Checklist of Entoprocta from the Gulf of Mexico. Taxon HabitatBiology Depth (m) Overall geographic range GMx range References/ Endnotes Phylum: Entoprocta Family: Pedicellinidae Pedicellina cernua (Pallas, 1774) ben, bns, hsb 1–16 cosmopolitan se 1, 6 Family: Barentsiidae Barentsia discreta (Busk, 1886) ben, bns, hsb 30 cosmopolitan se 1, 6 ...