Populations of the zoanthid Palythoa caribaeorum (Duchassaing and Michelotti, 1861) were monitored in a 2-yr study at several sites on the São Paulo coast, Brazil, to describe, quantify, and compare fission processes occurring in moderately vs. highly stressed environments. The effects of depth and season were also considered. Palythoa caribaeorum was found to reproduce by two new general processes of fission. The first process requires: A) the formation of crevices throughout the colony and the maintenance of basal coenenchyme throughout; B) the production of polyp-clusters which are connected to each other by thin basal coenenchyme, not readily visible; and C) the subsequent severance of the basal coenenchyme between polyp-clusters, creating true ramets. The first process included two variants: edge fission and polyp-cluster release. The second fission process was characterized by directional growth of tissue and a subsequent breaking away and dispersing of the ramets. It also included two variants: tissue outgrowth and polyp-ball production. Of the monitored colonies, 55% (nt = 579) exhibited at least one variant of fission, yielding 1304 ramets over 1 yr. Edge fission was the dominant form of asexual reproduction in this species. We found no evidence to support the hypothesis that higher environmental stress results in increased ramet production among sites, depths, or seasons. Fission occurred year-round and in colonies of all sizes. The minimum size of a colony reproducing by fission was 5 cm2. A significant positive linear relationship was found between colony area and number of ramets produced per colony. Ramet release also occurred year-round, although the frequency of release was significantly lower during the winter, when environmental conditions were harsher. This is the first report of tissue outgrowth, polyp-ball production, and polyp-cluster release for the genus Palythoa, and the first report of polyp-ball production within the Zoanthidea. There appear to be no analogues of polyp-cluster release within the Cnidaria. Fission in P. caribaeorum appears to be a conservative trait over a wide geographical range. It also seems to be endogenously controlled (genetically programmed) responding to colony growth constraints. Exogenous factors, however, may help to define the variant of fission used and the quantity of ramets produced at a given time. The adaptive value of fission for P. caribaeorum lies in its contribution to the number of clone-mates (increasing population size). It represents a critical and important form of asexual reproduction, helping to explain the ecological and evolutionary success of this species in the western Atlantic.761126Acosta, A., (1999) Ecologia Da Reprodução Assexuada de Palythoa caribaeorum (Zoanthidea: Cnidaria), 215p. , Tese de Doutor, Instituto de Biologia, Universidade Estadual de Campinas, S.P. BrazilDisease in zoanthids: Dynamics in space and time (2001) Hydrobiologia, 460, pp. 113-130Asbahr, M., Reproductive effort in Palythoa caribaeorum (2000) Proc. 9th Int. Coral Reef Symp., p. 295. , Bali. AbstractSammarco, P.W., Duarte, L.F., Asexual reproduction in a zoanthid by fragmentation (2001) Bull. Mar. Sci., 68, pp. 363-381Akcakaya, H.R., Burgman, M.A., Ginzburg, L.R., Applied population ecology: Principles and computer exercises using RAMAS Ecolab 1.0 (1997) Applied Biomathematics, 255p. , SetauketAnthony, K.R.N., Prey capture by the sea anemone Metridium senile: Effects of body size, flow regime, and upstream neighbors (1997) Biol. Bull., 192, pp. 73-86Ayre, D.J., Resing, J.M., Sexual and asexual production of planulae in reef corals (1986) Mar. Biol., 90, pp. 187-190Bell, G., (1982) The Masterpiece of Nature: The Evolution and Genetics of Sexuality, 635p. , Croom Helm, London and CanberraBurnett, W.J., Benzie, J.A.H., Beardmore, J.A., Ryland, J.S., High genetic variability and patchiness in a common Great Barrier Reef zoanthid (Palythoa caesia) (1994) Mar. Biol., 121, pp. 153-160Patterns of genetic subdivision in populations of a clonal cnidarian, Zoanthus coppingeri, from the Great Barrier Reef (1995) Mar. Biol., 122, pp. 665-673Bucklin, A., Growth and asexual reproduction of the sea anemone Metridium: Comparative laboratory studies of three species (1987) J. Exp. Mar. Biol. Ecol., 110, pp. 41-52Cairns, S.D., Asexual reproduction in solitary scleractinia (1988) Proc. 6th Int. Coral Reef Symp., 2, pp. 641-645. , TownsvilleCalgren, O., Ceriantharia and Zoantharia. British Museum (Natural History), Great Barrier Reef Expedition 1928-1929 (1937) Scientific Reports, 5 (5), pp. 25-209Cameron, A.M., Endean, R., Do long-lived species structure coral reefs ecosystems (1985) Proc. 5th Int. Coral Reef Congr., 6, pp. 211-215. , TahitiChao, S.M., Tsai, C.C., Reproduction and population dynamics of the fissiparous brittle star Ophiactis savignyi (Echinodermata: Ophiuroidea) (1995) Mar. Biol., 124, pp. 77-83Chia, F.S., Sea anemone reproduction: Patterns and adaptive radiations (1976) Coelenterate Ecology and Behavior, pp. 261-269. , G. O. Mackie, ed. Plenum Press, New YorkCoates, A.G., Jackson, J.B.C., Morphological themes in the evolution of clonal and aclonal marine invertebrates (1985) Population Biology and Evolution of Clonal Organisms, pp. 67-106. , J.B.C. Jackson, L.W. Buss, and R.E. Cook, eds. Yale University Press, New HavenCook, R.E., Asexual reproduction: A further consideration (1978) Amer. Nat., 113, pp. 769-772Clonal plant populations (1983) Am. Sci., 71, pp. 244-253Growth and development in clonal plant populations (1985) Population Biology and Evolution of Clonal Organisms, pp. 259-296. , J.B.C. Jackson, L.W. Buss, and R.E. Cook, eds. Yale University Press, New HavenCooke, W.J., Reproduction, growth, and some tolerances of Zoanthus pacificus and Palythoa vestitus in Kaneohe Bay, Hawaii (1976) Coelenterate Ecology and Behavior, pp. 281-288. , G.O. Mackie, ed. Plenum Press, New YorkCrowell, S., Oates, S., Metamorphosis and reproduction by transverse fission in an Edwardsiid anemone (1980) Developmental and Cellular Biology of Coelenterates, pp. 139-142. , P. Tardent and R. Tarden, eds. Elsevier Press, AmsterdamDahan, M., Benayahu, Y., Clonal propagation by the azooxanthellate octocoral Dendronephthya hemprichi (1997) Coral Reefs, 16, pp. 5-12DeVantier, L.M., Endean, R., Observations of colony fission following ledge-formation in massive reef corals of the genus Porites (1989) Mar. Ecol. Prog. Ser., 58, pp. 191-195Diaz, J.M., Barrios, L.M., Cedales, M.H., Garzon-Ferreira, J., Geister, J., Lopez-Victoria, M., Ospina, G.H., Zea, S., (2000) Áreas Coralinas de Colombia, 176p. , Serie Publicaciones Especiales, No. 5. INVEMAR, Santa MartaDinesen, Z.D., Aspects of the life history of a stolon-bearing species of Efflatounaria (Octocorallia: Xeniidae) (1985) Proc. 5th Int. Coral Reef Congress, 6, pp. 89-94. , TahitiDuerden, J.E., Jamaican Actiniaria, Part I. The Zoantheae (1898) Trans. Roy. Dub. Soc., 6, pp. 329-384. , N.SEmson, R.H., Mladenov, P.V., Studies of the fissiparous holothurian Holothuria parvula (Echinodermata: Holothuroidea) (1987) J. Exp. Mar. Biol. Ecol., 111, pp. 195-211Fadlallah, Y.H., (1981) The Reproductive Biology of Three Species of Corals from Central California, 213p. , Ph.D. Diss., University of California, Santa CruzReproductive ecology of the coral Astrangia lajollaensis: Sexual and asexual patterns in a kelp forest habitat (1982) Oecologia, 55, pp. 379-388Karlson, R.H., Sebens, K.P., A comparative study of sexual reproduction in three species of Panamanian zoanthids (Coelenterata: Anthozoa) (1984) Bull. Mar. Sci., 35, pp. 80-89Gleibs, S., (1994) Role of a Toxic Secondary Metabolite in the Ecology of the Genus Palythoa (Anthozoa) a Zoanthid of the Caribbean, 107p. , Institut für Allgemeine und Spezielle Zoologie, Biologie, Thesis, Justus-Liebig-Universität Gießen, GermanyGonzález, A.M., (1999) Efecto del Tamaño Colonial en la Frecuencia de Fisión de Palythoa caribaeorum (Cnidaria: Zoanthidea) en Santa Marta, Caribe Colombiano, 60p. , Pontificia Universidad Javeriana, Facultad de Ciencias Básicas, Biología, Bogotá, Tesis de Grado de BiólogoAcosta, A., Colony size, fission, and effect of ramets to population growth in the zoanthid Palythoa caribaeorum (2000) 9th Int. Coral Reef Symp., p. 308. , Bali, IndonesiaHaddon, A.C., Shackleton, A.M., Actiniae: I Zoantheae. Reports on the Zoological Collections made in Torres Straits by A.C. Haddon, 1888-1889 (1891) Scient. Trans. R. Soc. Ser. 2, 4, pp. 674-699Harper, J.L., (1977) Population Biology of Plants, 890p. , Academic Press, New YorkHarrison, P.L., Wallace, C.C., Coral reproductive biology (1990) Ecosystems of the World, 25, Coral Reefs, pp. 181-183. , Z. Dubinsky, ed. Elsevier, New YorkHighsmith, R.C., Reproduction by fragmentation in corals (1982) Mar. Ecol. Prog. Ser., 7, pp. 207-226Riggs, A.C., DÁntonio, C.M., Survival of hurricane-generated coral fragments and a disturbance variant of reef calcification growth rates (1980) Oecologia, 46, pp. 322-329Hughes, R.N., (1989) A Functional Biology of Clonal Animals, 331p. , Chapman and Hall, New YorkHughes, T.P., Jackson, J.B.C., Do corals lie about their age? Some demographic consequences of partial mortality, fission and fusion (1980) Science, 209, pp. 713-715Jackson, J.B.C., Population dynamics and life histories of foliaceous corals (1985) Ecol. Monogr., 55, pp. 141-166Hunter, T., The energetics of asexual reproduction: Pedal laceration in the symbiotic sea anemone Aiptasia pulchella (1984) J. Exp. Mar. Ecol., 83, pp. 127-147Jackson, J.B.C., Buss, L.W., Cook, R.E., (1985) Population Biology and Evolution of Clonal Organisms, 465p. , Yale University Press, New HavenJohnson, L.L., Shick, J.M., Effects of fluctuating temperature and immersion on asexual reproduction in the intertidal sea anemone Haliplanella luciae (Verrill) in laboratory culture (1977) J. Exp. Mar. Biol. Ecol., 28, pp. 141-149Karlson, R.H., Disturbance and monopolization of a spatial resource by Zoanthus sociatus (Coelenterata, Anthozoa) (1983) Bull. Mar. Sci., 33, pp. 118-131Disturbance, colonial fragmentation, and size-dependent life history variation in two coral reef cnidarians (1986) Mar. Ecol. Prog. Ser., 28, pp. 245-249Size-dependent growth in two zoanthid species: A contrast in clonal strategies (1988) Ecology, 69, pp. 1219-1232Growth and survivorship of clonal fragments in Zoanthus solanderi Lesueur (1988) J. Exp. Mar. Biol. Ecol., 123, pp. 31-39Fission and the dynamics of genets and ramets in clonal cnidarian populations (1991) Hydrobiologia, 216, pp. 235-240Hughes, T.P., Karlson, S.R., Density-dependent dynamics of soft coral aggregations: The significance of clonal growth and form (1996) Ecology, 77, pp. 1592-1599Kimura, S., Hashimoto, Y., Yamazato, K., Toxicity of the zoanthid Palythoa tuberculosa (1972) Toxicon., 10, pp. 611-617Kramarsky, E.W., Fine, M., Loya, Y., Coral polyp expulsion (1997) Nature, 387, p. 137Larson, K.S., Larson, R.J., On the ecology of Isaurus duchassaingi (Cnidaria: Zoanthidea) from South Water Cay, Belize (1982) The Atlantic Barrier Reef Ecosystem at Carrie Bow Cay Belize, pp. 475-488. , K. Rutzler and I.G. Macintyre, eds. Smithsonian Contrib. Mar. Sci, Washington D.CLasker, H.R., Vegetative reproduction in the octocoral Briareum asbestinum (1983) J. Exp. Mar. Ecol., 72, pp. 157-169Clonal propagation and population dynamics of a gorgonian coral (1990) Ecology, 71, pp. 1578-1589Levins, R., (1968) Evolution in Changing Environments, 120p. , Princeton University Press, PrincetonMcFadden, C.S., Colony fission increases particle capture rates of a soft coral: Advantages of being a small colony (1986) J. Exp. Mar. Biol. Ecol., 103, pp. 1-20A comparative demographic analysis of clonal reproduction in a temperate soft coral (1991) Ecology, 72, pp. 1849-1866Migotto, A.E., Anthozoan bleaching on the southeastern coast of Brazil in the summer of 1994 (1997) Proc. 6th Conf. on Coelenterate Biology, pp. 329-335p. , AmsterdamMinasian, L.L., Characteristics of asexual reproduction in the sea anemone Haliplanella luciae reared in the laboratory (1976) Coelenterate Ecology and Behavior, pp. 289-298. , G.O. Mackie, ed. Plenum Press, New YorkThe effect of exogenous factors on morphology and asexual reproduction in laboratory cultures of the intertidal sea anemone, Haliplanella luciae (Verrill) (Anthozoa: Actiniaria) from Delaware (1979) J. Exp. Mar. Biol. Ecol., 40, pp. 235-246The relationship of size and biomass to fission rate in a clone of the sea Anemone, Haliplanella luciae (Verril) (1982) J. Exp. Mar. Biol. Ecol., 58, pp. 151-162Mariscal, R.N., Characteristics and regulation of fission activity in clonal cultures of the cosmopolitan sea anemone, Haliplanella luciae (1979) Biol. Bull., 157, pp. 478-493Mladenov, P.V., Environmental factors influencing asexual reproductive processes in echinoderms (1996) Oceanol. Acta, 19, pp. 227-235Muirhead, A., Ryland, J.S., A review of the genus Isaurus (Zoanthidea) including new records from Fiji (1985) J. Nat. Hist., 19, pp. 323-335Newell, S.J., Solbrig, O.T., Kincaid, D.T., Studies on the population biology of the genus Viola III the demography of Viola blanda and Viola pallens (1981) J. Ecol., 69, pp. 997-1016Okamura, B., The effects of ambient flow velocity, colony size, and upstream colonies on the feeding success of Bryozoa. II. Conopeum reticulum, an encrusting species (1985) J. Exp. Mar. Biol. Ecol., 89, pp. 69-80Oliver, J.S., Selection for asexual reproduction in an Antarctic polychaete worm (1984) Mar. Ecol. Prog. Ser., 19, pp. 33-38Ottesen, P.O., Lucas, J.S., Divide or broadcast: Interrelation of asexual and sexual reproduction in a population of the fissiparous hermaphroditic seastar Nepanthia belcheri (Asteroidea: Asterinidae) (1982) Mar. Biol., 69, pp. 223-233Pastorok, R.A., Bilyard, G.R., Effects of sewage pollution on coral-reef communities (1985) Mar. Ecol. Prog. Ser., 21, pp. 175-189Rocha, L.A., Bowen, B.W., Assessment of cryptic reef fish species in Brazil using molecular markers (2000) Proc. 9th Int. Coral Reef Symp., p. 21. , Bali. AbstractRogers, C.S., Responses of coral reefs and reef organisms to sedimentation (1990) Mar. Ecol. Prog. Ser., 62, pp. 185-202Rosen, B.R., Taylor, J.D., Reef coral from Aldabra: New mode of reproduction (1969) Science, 166, pp. 119-120Ryland, J.S., Reproduction in Zoanthidea (Anthozoa: Hexacorallia) (1997) Invertebr. Reprod. Dev., 31, pp. 177-188Warner, G.F., Growth and form in modular animals: Ideas on the size and arrangement of zooids (1986) Phil. Trans. R. Soc. Lond. B., 313, pp. 53-76Sammarco, P.W., Polyp bail-out: An escape response to environmental stress and a new means of reproduction in corals (1982) Mar. Ecol. Prog. Ser., 10, pp. 57-65Scheer, G., Die formenvielfalt der riffkorallen (1959) Bericht 1958/1959 Naturwissenschaften Verein Dormstadt, 50, pp. 50-67Schmidt, H., Anthopleura stellula (Actiniaria, Actiniidae) and its reproduction by transverse fission (1970) Mar. Biol., 5, pp. 245-255Sebens, K.P., The energetics of asexual reproduction and colony formation in benthic marine invertebrates (1979) Am. Zool., 19, pp. 683-697The regulation of asexual reproduction and indeterminate body size in the sea anemone Anthopleura elegantissima (Brandt) (1980) Biol. Bull., 158, pp. 370-382Intertidal distribution of zoanthids on the Caribbean coast of Panama: Effects of predation and desiccation (1982) Bull. Mar. Sci., 32, pp. 316-335The limits to indeterminate growth: An optimal size variant applied to passive suspension feeders (1982) Ecology, 63, pp. 209-222Shick, J.M., Ecological physiology and genetics of the colonizing actinian Haliplanella luciae (1976) Coelenterate Ecology and Behavior, pp. 137-146. , G.O. Mackie, ed. Plenum Press, New York(1991) A Functional Biology of Sea Anemones, 424p. , Chapman & Hall, New YorkHoffmann, R.J., Effects of the trophic and physical environments on asexual reproduction and body size in the sea anemone Metridium senile (1980) Developmental and Cellular Biology of Coelenterates, pp. 211-216. , P. Tardent and R. Tardent, eds. NorthHolland Biomedical Press, New YorkShostak, S., 2. Cnidaria (1993) Reproductive Biology of Invertebrates. VI. Asexual Propagation and Reproductive Strategies, pp. 45-104. , K.G. Adiyodi and R.G. Adiyodi, eds. John Wiley & Sons, New YorkSmith, N., Lenhoff, M., Regulation of frequency of pedal laceration in a sea anemone (1976) Coelenterate Ecology and Behavior, pp. 117-125. , G.O. Mackie, ed. Plenum Press, New YorkSoong, K., Shiau, Y.S., Chen, C.P., Morphological and reproductive variations of the zoanthid, Sphenopus marsupialis, from two locations in Taiwan (1995) Proc. 6th Int. Conf. Coelenterate Biol., 91p. , AmsterdamMorphological and life history divergence of the zoanthid, Sphenopus marsupialis off the Taiwanese coast (1999) Zool. Stud., 38, pp. 333-343Sokal, R.R., Rohlf, F.J., (1995) Biometry, 887p. , W.H. Freeman and Co., New YorkSteen, R.G., Muscatine, L., Daily budgets of photosynthetically fixed carbon in symbiotic zoanthids (1984) Biol. Bull., 167, pp. 477-487Stoner, D.S., Fragmentation: A mechanism for the stimulation of genet growth rates in an encrusting colonial ascidian (1989) Bull. Mar. Sci., 45, pp. 277-287Suchanek, T.H., Green, D.J., Interspecific competition between Palythoa caribaeorum and other sessile invertebrates on St.Croix reefs, US Virgin Islands (1981) Proc. 4th Int. Coral Reef Symp., 2, pp. 679-684. , ManilaTanner, J.E., The effects of density on the zoanthid Palythoa caesia (1997) J. Anim. Ecol., 66, pp. 793-810Density-dependent population dynamics in clonal organisms: A modeling approach (1999) J. Anim. Ecol., 68, pp. 390-399Tun, K.P.P., Cheshire, A.C., Chou, L.M., Twenty-four hour in situ monitoring of oxygen production and respiration of the colonial zoanthid Palythoa (1997) Environ. Monit. Assess., 44, pp. 33-43Vaughan, T.W., Wells, J.W., (1943) Revision of the Suborders Families, and Genera of the Scleractinia, 363p. , Geol. Soc. of America, BaltimoreVerrill, A.E., Notes in radiata. Review of the corals and polyps of the west coast of America (1869) Trans. Connect. Acad., 1, pp. 1868-1870Walker, T.A., Bull, G.D., A newly discovered method of reproduction in gorgonian coral (1983) Mar. Ecol. Prog. Ser., 12, pp. 137-143Williams, G.C., (1975) Sex and Evolution, 210p. , Princeton University Press, PrincetonWulff, J.L., Dispersal and survival of fragments of coral reef sponges (1985) Proc. 5th Int. Coral Reef Congr., 5, pp. 119-124. , TahitiYamazato, K., Yoshimoto, F., Yoshihara, N., Reproductive cycle of a Zoanthid, Palythoa tuberculosa (Esper) (1973) Publ. Seto. Mar. Biol. Lab., 20, pp. 275-283Isa, T., Dynamics of colonial growth in a zoanthid, Palythoa tuberculosa (Esper) (1981) Proc. 4th Int. Coral Reef Symp., 2, 760p. , Manila