No description available.

A comprehensive worldwide review and revision of the genus Sternaspis (Polychaeta: Sternaspidae) is presented based on type material, or material collected from type localities. The phylogeny was reconstructed using morphological characters and PAUP* with maximum parsimony set as the criterion. The more important characters were: the form of pharyngeal spines or their apposition to each other within a row; the form or distribution of cuticular papillae; number of chaetal fascicles associated with the margins of the ventral shield; and the presence or position of the peg chaetae. Sternaspis scutata (Ranzani. 1817) is synonymised with three other species; S. costata Marenzeller, 1979 is synonymised with one other species. S. affinis Stimpson, 1864 and S. spinosa Sluiter, 1882 are emended. S. fossor var. africana Augener, 1918 is raised to species status as S. africana. Two new species, S. andamana and S. gudmundi are also described. Comments on all valid species are provided.

Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Includes bibliographical references. Issued in print and online. Available via ProQuest Digital Dissertations.

Serpulidae Rafinesque, 1815 é uma das famílias de poliquetas mais facilmente reconhecíveis, por viverem em tubos calcários e possuírem o corpo dividido em três regiões bem definidas, coroa branquial, tórax e abdômen, geralmente com um opérculo, que fecha a abertura do tubo quando a coroa branquial é retraída, e uma membrana torácica, que é um prolongamento do colar, estendendo-se ao longo do tórax dorsalmente por número variável de setígeros. São muito abundantes no litoral brasileiro e importantes na comunidade incrustante, que reveste pedras, algas e demais estruturas que forneçam o substrato adequado para a instalação destes animais, sendo um dos principais grupos de poliquetas em estudos de bioinvasão. Ao longo da história taxonômica da família, as relações filogenéticas e a classificação sistemática do grupo passaram por diversas alterações e atualmente, com base em estudos morfológicos e moleculares, são considerados como grupo irmão de Fabriciidae Rioja, 1923, e o clado, grupo-irmão de Sabellidae Latreille, 1825. O presente trabalho é um dos primeiros estudos de cunho taxonômico tratando especificamente da Família Serpulidae ao longo da costa brasileira, com o objetivo de identificar e descrever as espécies destes animais encontradas entre as regiões Sul-Nordeste do país; foram analisados 443 indivíduos, pertencentes a dez gêneros e 16 espécies, uma das quais é nova ocorrência para o Brasil e outra é nova para a ciência / Serpulidae Rafinesque, 1815 is one of the most easily recognizable families of polychaetes, because these animals live in calcareous tubes and have the body divided into three well-defined regions, the branchial crown, thorax and abdomen, usually with an operculum, which closes the mouth of the tube when the branchial crown is retracted, and a thoracic membrane, which is an extension of the collar dorsally, extending along the thorax for a variable number of chaetigers. Serpulids are very abundant in Brazil and important in the fouling community, coating rocks, algae and other structures which provide the appropriate substrate for the installation of these animals, being one of the major groups of polychaetes in bioinvasion studies. Our understanding on the phylogenetic relationships within Serpulidae and between the family and the closely related Fabriciidae Rioja, 1923 and Sabellidae Latreille, 1825 has changed through time; currently, based on both morphological and molecular studies, serpulids are regarded as the sister group of Fabriciidae and this clade is sister to Sabellidae. The present study is one of the first taxonomic studies dealing specifically with the Family Serpulidae along the Brazilian coast, aiming to identify and describe the species found between the southern and northeastern regions; 443 specimens were analyzed, belonging to ten genera and 16 species, of which one species is firstly reported for Brazilian waters and another is new to science

Response surface techniques were used to investigate the tolerances of the planktonic larvae of three spionid polychaetes to a variety of temperature and salinity combinations. Two of the spionids were morphologically very similar members of the genus Boccar.dia., B. proboscidea and B. columbiana which occupy nearly identical geographic ranges. The other was Polydora giardi a common coinhabitant with B. columbiana. In addition a third independent parameter, food concentration, was added to the study of B. columbiana and P. giardi. The larvae of the two Boccardia species were extremely euryhaline, in marked contrast to those of Polydora giardi which were confined to an extremely narrow salinity range. They were distinctly sepArated by their temperature tolerances, however; B. proboscidea exhibiting maximum growth and survival at the upper temperature extremes of the design , while B. columbiana preferred a moderate to low temperature regime. The larvae of P. giardi are extremely eurythermal and are only slightly affected by temperature variations. It is suggested that the reproductive schedule of the three spionids can be explained, at least in part, in terms of the information generated by the response surfaces. The long duration of the reproductive season of P. giardi is a reflection of the larvae's eurythermal nature. The inability of the larvae of P. giardi to cope with osmotic stress and the lack of an abundance of food items in the plankton during the winter months are probably of greater consequence in dictating the cessation of the reproductive season, than the minimum water temperatures that occur at t.his time. The Boccardia larvae are in contrast less subject to the above considerations but are very dependent on the ambient water temperature to promote larval survival and growth.

No description available.

The taxonomic composition of the diatom assemblages inhabiting the substrate on the mudflat, and the effects of a cohabiting deposit-feeding invertebrate on the diatom assemblage structure are the subjects of this paper. While pelagic diatoms have received considerable attention in the literature to date, comparatively little is known about the ecology and distribution of benthic diatoms are known to be cosmopolitan in their distributions (Alee, 1950). These plants have been found to be opportunistic species in that they are quick to respond to relatively small perturbations in physical conditions. It has also been demonstrated that distinct associations of diatoms exist (McIntire and Overton, 1971). Generalizations concerning habitat preference and the assemblages that can be found within a specific biotope have also been made (Hendey, 1954; Round, 1960' Aleem, 1950). Examination of the biotic interaction between a deposit-feeder and the diatoms (Division: Bacillarioohyceae) on Lawson's mudflat located in Tomales Bay, California was initiated October, 1975, and was concluded December, 1976. The site chosen for the research was a dense bed of the Maldanid Polychaete, Axiothella rubrocincta (Johnson). Control areas immediately adjacent to the north-eastern and south-western boundaries of the bed were also studied. The morphology and feeding behavior of this deposit-feeder has been investigated by Kudenov (1971) and Weinberg (in press). Kudenov suggested that A. rubrocincta is a non-selective deposit-feeder and he also showed that it habitually ingested large amounts of sediment. Hargrave (1976) states that the efficiency with which deposit-feeders assimilate organic matter in the sediments is related to both the composition of the organic matter and the size of the particles ingested. Perkins' (1960) observations indicate that the relationship between the organic content and particle size is a major controlling factor in determining diatom community structure. Because Axiothella rubrocincta attains high densities and ingests sediment, this polychaete may affect the structure of diatom assemblages either directly by predation or indirectly by physically altering the environment upon which the diatoms exist. Therefore, it is hypothesized that by reworking the sediment and thereby altering the sediment composition, deposit-feeders may be creating and maintaining a niche wherein specific diatoms can establish themselves in distinct assemblages to the exclusion of other competing diatom species.

In the present study, the sediment reworking rates, irrigation rates, and activity patterns of Axiotheata rubrocincta have been investigated. The results are compared with studies of other deposit feeding polychaetes. Because sediment ingestion is a feeding process, it has been necessary to examine some aspects of the feeding morphology and ecology of A. rubrocincta. Some of these findings differed from the results of Spies (MS.). The feeding biology and morphology of two additional maldanidae, Clymenella sp. and Praxillella affinis pacifica (Berkeley, 1929) have been studied. These finding are compared with earlier studies on maldanid genera and species by Pilgrim (1965b, 1966a).

No description available.

Terebrasabella heterouncinata is a small K-selected sabellid polychaete. It is a simultaneous hermaphrodite with a semi-continuous mode of reproduction, producing relatively few large eggs that are brooded within the parental burrow until the larvae emerge, to settle on the growing edge of the abalone shell. Despite its low fecundity, this worm has become problematic on abalone farms in South Africa. The present study was conducted to gain an understanding of the life history patterns of T. helerouncinata to determine how they contributed to the success of these worms under altered conditions. This study demonstrated that conditions prevalent on abalone farms were conducive to enhancing the reproductive success of this worm, and suggests that larger, more fecund worms may have been selected for in the decade that these worms have been present on the farms. Increased nutrient availability, and possibly the increased stability of the farm environment relative to its natural environment, has led to a 1.5-fold increase in the average size of the worms. Body size was found to be positively correlated with brood size, and this resulted in worms on farms brooding 3 to 4.5 times more offspring at a time than worms from wild abalone. The ability to increase the number of eggs produced at a time may have been limited by the fact that these worms have only two ovaries. Thus, the increase in fecundity may have been related primarily to the increase in the rate at which the eggs were laid by the worms on the farms, and the increase in the coelomic space available for the storage of these rapidly developing eggs. The ability to increase the rate at which oocytes develop may be related to the vitellogenic mechanisms employed by these worms. Vitellogenic oocytes are able to incorporate high molecular weight yolk precursors from the surrounding coelomic fluid through endocytotic activity. This may allow the oocytes to increase the rate at which they incorporate yolk material under conditions of nutrient enrichment. The increase in fecundity did not occur at the expense of offspring size and, presumably, quality. The increased reproductive output on the farms was compounded by a proportionate increase in the number of reproducing worms within the population. In addition, these worms are long-lived (worms from farmed abalone reached a maximum age of approximately 40 months) and exhibit negligible senescence. Thus, their reproductive output did not change significantly with an increase in age. Furthermore, the proportion of the reproductive worms did not decrease with an increase in age. Thus, within the age range tested, worms of all ages have the potential to make equal contributions to population growth. While diet and abalone stocking density could not be identified as having a significant effect on reproductive output and infestation rate under intensive culture conditions, it was demonstrated that in a naïve abalone population, the total intensity of infestation increased exponentially with time. This increase may be a consequence of an increase in fertilisation success. These worms continuously produce entaquasperm that are released into the water column. The sperm are collected by other individuals that then store the sperm in a single spermatheca. The ability to store sperm relieves individuals of a dependence on the synchronisation of spawning of eggs and sperm. As the population size and density increases, there could be more individuals releasing sperm into the water column, resulting in a continuous supply of sperm. The increased production of eggs would therefore not be constrained by a lack of sperm. The stored sperm are released into the brood chamber to fertilise eggs as they are laid, and this would probably increase the fertilisation success in the species. This study also provides evidence to suggest that reproduction in this worm has a seasonal component. Future studies should concentrate on measuring fertilisation success in greater detail, measuring the effect of season on reproduction, determining whether there are genetic differences between worms on farmed and wild abalone and determining whether wild worms have similar life-spans and age-related fecundity as worms on farms.