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Academic literature on the topic 'Annelids'
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Journal articles on the topic "Annelids"
1
McHugh, Damhnait. "Molecular phylogeny of the Annelida." Canadian Journal of Zoology 78, no. 11 (2000): 1873–84. http://dx.doi.org/10.1139/z00-141.
Full textAbstract:
Traditionally, the Annelida has been classified as a group comprising the Polychaeta and the Clitellata. Recent phylogenetic analyses have led to profound changes in the view that the Annelida, as traditionally formulated, is a natural, monophyletic group. Both molecular and morphological analyses support placement of the Siboglinidae (formerly the Pogonophora) as a derived group within the Annelida; there is also evidence, based on molecular analysis of the nuclear gene elongation factor-1α, that the unsegmented echiurids are derived annelids. While monophyly of the Clitellata is well-supported by both molecular and morphological analyses, there is no molecular evidence to support monophyly of the polychaete annelids; the Clitellata fall within a paraphyletic polychaete grade. Relationships among groups of polychaete annelids have not yet been resolved by molecular analysis. Within the Clitellata, paraphyly of the Oligochaeta was indicated in a phylogenetic analysis of cytochrome c oxidase I, which supported a sister relationship between the leeches, including an acanthobdellid and a branchiobdellid, and two of the four oligochaetes in the analysis. There is some evidence from analysis of 18S rRNA sequences for a sister-group relationship between the clitellates and the taxon Aeolosoma. There is no agreement regarding the body form of the basal annelid, and while molecular analyses provide strong support for the Eutrochozoa, the identity of sister-group to the Annelida among the Eutrochozoa remains enigmatic. It is recommended that future investigations include additional conserved gene sequences and expanded taxon sampling. It is likely that the most productive approach to resolving annelid phylogeny, and thus increasing our understanding of annelid evolution, will come from combined analyses of several gene sequences.
2
ROUSE, GREG W., and FREDRIK PLEIJEL. "Annelida*." Zootaxa 1668, no. 1 (2007): 245–64. http://dx.doi.org/10.11646/zootaxa.1668.1.13.
Full textAbstract:
The first annelids were formally described by Linnaeus (1758) and we here briefly review the history and composition of the group. The traditionally recognized classes were Polychaeta, Oligochaeta and Hirudinea. The latter two are now viewed as the taxon Clitellata, since recognizing Hirudinea with class rank renders Oligochaeta paraphyletic. Polychaeta appears to contain Clitellata, and so may be synonymous with Annelida. Current consensus would place previously recognized phyla such as Echiura, Pogonophora, Sipuncula and Vestimentifera as annelids, though relationships among these and the various other annelid lineages are still unresolved.
3
Mucciolo, Serena, Andrea Desiderato, Marika Salonna, et al. "Finding Aquaporins in Annelids: An Evolutionary Analysis and a Case Study." Cells 10, no. 12 (2021): 3562. http://dx.doi.org/10.3390/cells10123562.
Full textAbstract:
Aquaporins (AQPs) are a family of membrane channels facilitating diffusion of water and small solutes into and out of cells. Despite their biological relevance in osmoregulation and ubiquitous distribution throughout metazoans, the presence of AQPs in annelids has been poorly investigated. Here, we searched and annotated Aqp sequences in public genomes and transcriptomes of annelids, inferred their evolutionary relationships through phylogenetic analyses and discussed their putative physiological relevance. We identified a total of 401 Aqp sequences in 27 annelid species, including 367 sequences previously unrecognized as Aqps. Similar to vertebrates, phylogenetic tree reconstructions clustered these annelid Aqps in four clades: AQP1-like, AQP3-like, AQP8-like and AQP11-like. We found no clear indication of the existence of paralogs exclusive to annelids; however, several gene duplications seem to have occurred in the ancestors of some Sedentaria annelid families, mainly in the AQP1-like clade. Three of the six Aqps annotated in Alitta succinea, an estuarine annelid showing high salinity tolerance, were validated by RT-PCR sequencing, and their similarity to human AQPs was investigated at the level of “key” conserved residues and predicted three-dimensional structure. Our results suggest a diversification of the structures and functions of AQPs in Annelida comparable to that observed in other taxa.
4
Parry, Luke A., Gregory D. Edgecombe, Danny Eibye-Jacobsen, and Jakob Vinther. "The impact of fossil data on annelid phylogeny inferred from discrete morphological characters." Proceedings of the Royal Society B: Biological Sciences 283, no. 1837 (2016): 20161378. http://dx.doi.org/10.1098/rspb.2016.1378.
Full textAbstract:
As a result of their plastic body plan, the relationships of the annelid worms and even the taxonomic makeup of the phylum have long been contentious. Morphological cladistic analyses have typically recovered a monophyletic Polychaeta, with the simple-bodied forms assigned to an early-diverging clade or grade. This is in stark contrast to molecular trees, in which polychaetes are paraphyletic and include clitellates, echiurans and sipunculans. Cambrian stem group annelid body fossils are complex-bodied polychaetes that possess well-developed parapodia and paired head appendages (palps), suggesting that the root of annelids is misplaced in morphological trees. We present a reinvestigation of the morphology of key fossil taxa and include them in a comprehensive phylogenetic analysis of annelids. Analyses using probabilistic methods and both equal- and implied-weights parsimony recover paraphyletic polychaetes and support the conclusion that echiurans and clitellates are derived polychaetes. Morphological trees including fossils depict two main clades of crown-group annelids that are similar, but not identical, to Errantia and Sedentaria, the fundamental groupings in transcriptomic analyses. Removing fossils yields trees that are often less resolved and/or root the tree in greater conflict with molecular topologies. While there are many topological similarities between the analyses herein and recent phylogenomic hypotheses, differences include the exclusion of Sipuncula from Annelida and the taxa forming the deepest crown-group divergences.
5
Bartolomaeus, Thomas. "Head Kidneys in Hatchlings of Scoloplos Armiger (Annelida: Orbiniida): Implications for the Occurrence of Protonephridia in Lecithotrophic Larvae." Journal of the Marine Biological Association of the United Kingdom 78, no. 1 (1998): 183–92. http://dx.doi.org/10.1017/s0025315400040017.
Full textAbstract:
It is generally believed that lecithotrophic larvae of annelids do not possess functional excretory organs. However, as in certain annelids the planktotrophic trochophora larva has been secondarily modified into a lecithotrophic developmental stage and because protonephridia are characteristic for the trochophora, lecithotrophic developmental stages should also possess such organs. To test this assumption hatchlings of the orbiniidan Scoloplos armiger, which develops directly without a free-living larval stage, were investigated ultrastrucrurally. Each hatchling possesses a pair of protonephridia which lie caudal to the eyes and almost level with the frontal margin of the foregut. Each organ consists of three multiciliated cells, a terminal cell, a duct cell and a nephropore cell. The terminal cell bears a distally oriented hollow cytoplasmic cylinder, which surrounds the cilia. Adherens junctions connect this structure to the duct cell. Several clefts and pores perforate the wall of the hollow cylinder. Extracellular material covers the pores and clefts and thus may function as a molecular sieve during filtration. A comparison with the protonephridia of other annelid larvae reveals: (1) that one pair of protonephridial head kidneys consisting of a terminal cell, a duct cell and a nephropore cell must be assumed for the trochophore in the ground pattern of annelids and (2) that these organs are preserved when lecithotrophic larval stages evolved within the Annelida
6
Capa, María, and Pat Hutchings. "Annelid Diversity: Historical Overview and Future Perspectives." Diversity 13, no. 3 (2021): 129. http://dx.doi.org/10.3390/d13030129.
Full textAbstract:
Annelida is a ubiquitous, common and diverse group of organisms, found in terrestrial, fresh waters and marine environments. Despite the large efforts put into resolving the evolutionary relationships of these and other Lophotrochozoa, and the delineation of the basal nodes within the group, these are still unanswered. Annelida holds an enormous diversity of forms and biological strategies alongside a large number of species, following Arthropoda, Mollusca, Vertebrata and perhaps Platyhelminthes, among the species most rich in phyla within Metazoa. The number of currently accepted annelid species changes rapidly when taxonomic groups are revised due to synonymies and descriptions of a new species. The group is also experiencing a recent increase in species numbers as a consequence of the use of molecular taxonomy methods, which allows the delineation of the entities within species complexes. This review aims at succinctly reviewing the state-of-the-art of annelid diversity and summarizing the main systematic revisions carried out in the group. Moreover, it should be considered as the introduction to the papers that form this Special Issue on Systematics and Biodiversity of Annelids.
7
MAGALHÃES, WAGNER F., PAT HUTCHINGS, ALEJANDRO OCEGUERA-FIGUEROA, et al. "Segmented worms (Phylum Annelida): a celebration of twenty years of progress through Zootaxa and call for action on the taxonomic work that remains." Zootaxa 4979, no. 1 (2021): 190–211. http://dx.doi.org/10.11646/zootaxa.4979.1.18.
Full textAbstract:
Zootaxa has been the leading journal on invertebrate systematics especially within Annelida. Our current estimates indicate annelids include approximately 20,200 valid species of polychaetes, oligochaetes, leeches, sipunculans and echiurans. We include herein the impact of Zootaxa on the description of new annelid species in the last two decades. Since 2001, there have been over 1,300 new annelid taxa published in about 630 papers. The majority of these are polychaetes (921 new species and 40 new genera) followed by oligochaetes (308 new species and 10 new genera) and leeches (21 new species). The numerous papers dealing with new polychaete species have provided us a clear picture on which polychaete families have had the most taxonomic effort and which authors and countries have been the most prolific of descriptions of new taxa. An estimated additional 10,000+ species remain to be described in the phylum, thus we urge annelid workers to continue their efforts and aid in training a new generation of taxonomists focused on this ecologically important group.
8
Kennedy, Victor S. "A summer benthic survey in Conception Bay, Newfoundland, emphasizing zoogeography of annelids and amphipods." Canadian Journal of Zoology 63, no. 8 (1985): 1863–69. http://dx.doi.org/10.1139/z85-277.
Full textAbstract:
A limited benthic survey was made in August in Conception Bay, Newfoundland, using a 0.2-m2 van Veen grab sampler. Nine stations were sampled in a relatively shallow (62–79 m), soft-bottom (predominantly silt) region with low bottom water (0.2–1.4 °C) and sediment (0.5–2.0 °C) temperatures. Annelids (32 species) and amphipods (18 species) were the common invertebrates collected, with annelids being more numerous, both in numbers of individuals and of species. Deposit-feeding annelids outnumbered carnivores, with subsurface deposit feeders more abundant than surface feeders. Sedentary individuals predominated. Most annelid species had boreal–temperate affinities, with few arctic species being present. Detritivorous amphipods predominated, followed by scrapers and scavengers. Nearly all were burrowers. All the amphipod species were arctic–boreal in distribution and most do not range as far south as do the annelids. Molluscs were small and uncommon and they, like the remaining uncommon components of the biomass, were not identified to any extent.
9
Kostyuchenko, Roman P., and Vitaly V. Kozin. "Comparative Aspects of Annelid Regeneration: Towards Understanding the Mechanisms of Regeneration." Genes 12, no. 8 (2021): 1148. http://dx.doi.org/10.3390/genes12081148.
Full textAbstract:
The question of why animals vary in their ability to regenerate remains one of the most intriguing questions in biology. Annelids are a large and diverse phylum, many members of which are capable of extensive regeneration such as regrowth of a complete head or tail and whole-body regeneration, even from few segments. On the other hand, some representatives of both of the two major annelid clades show very limited tissue regeneration and are completely incapable of segmental regeneration. Here we review experimental and descriptive data on annelid regeneration, obtained at different levels of organization, from data on organs and tissues to intracellular and transcriptomic data. Understanding the variety of the cellular and molecular basis of regeneration in annelids can help one to address important questions about the role of stem/dedifferentiated cells and “molecular morphallaxis” in annelid regeneration as well as the evolution of regeneration in general.
10
Clauss, Wolfgang G. "Epithelial transport and osmoregulation in annelids." Canadian Journal of Zoology 79, no. 2 (2001): 192–203. http://dx.doi.org/10.1139/z00-200.
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Epithelial transport related to osmoregulation has so far not been extensively investigated in annelids. Compared with the large body of information about ion transport across crustacean or insect epithelia, only a few studies have been done with isolated preparations of annelids, using the body wall of marine polychaetes or Hirudinea. Nephridial function and general body homeostasis have received more attention, and have probably been best investigated in Hirudinea. With recent advances in the molecular physiology of epithelial transport systems in vertebrates, the cloning of various transporters and ion channels, and the considerable number of osmoregulatory peptides that have now been found and analyzed from annelids, it should now be possible, and is timely, to conduct functional studies on individual selected epithelial preparations or isolated cells from annelids. Such studies may be important for establishing useful models with somewhat less complexity than mammalian systems. For example, annelids lack aldosterone, an important osmoregulatory hormone, which is a key factor in the regulation of sodium reabsorption in vertebrates. Therefore, not only would such studies contribute to annelid physiology, but they would be important in a broader sense for understanding osmoregulation and its evolution. They should also facilitate the discovery and investigation of new specific regulatory pathways.