Ragworms and Allies in June 2018 by Aleš Buček

Ragworms and Allies from Airport Rd, Sitka, AK, US on June 2, 2026 at 09:02 PM by annanw

Ragworms and Allies from Hoonah-Angoon, AK, USA on May 23, 2011 at 05:44 PM by Joe Tomoleoni. large worm (1m/3ft+ in length) swimming at surface or just subsurface

Nereidid polychaetes are well known from shallow marine habitats, but their diversity in the deep sea is poorly known. Here we describe an unusual new nereidid species found at methane seeps off the P...

Perinereis cultrifera (Grube, 1840), comúnmente conocido como gusano coreano o coreano en el ámbito de la pesca, es un anélido poliqueto de la familia Nereididae ampliamente distribuido en zonas costeras. Es una especie de gran importancia económica debido a su uso extendido como cebo vivo en la pesca deportiva y como alimento en la acuicultura de crustáceos.

Platynereis dumerilii (Annelida, Nereididae) es un poliqueto cuyo ciclo vital se caracteriza por varias transiciones en el comportamiento y en el hábitat. La larva primaria, de vida libre y nadadora, sufre una metamorfosis y se asienta en hábitats someros con vegetación. En esta fase, Platynereis secreta tubos de moco que quedan adheridos a la vegetación. Tras otra metamorfosis, el adulto ya maduro nada hasta la superficie del agua y libera los gametos para una fecundación externa.

Abstract. The status of the subfamily Dendronereidinae has been subject to uncertainty, because its primary defining morphological character (the presence

In this study, we propose a new biometric methodology for annelids, based on the number of chaetiger segments as an indicator of growth (independent variable), relating to other structures, such as the number of paragnaths and parapodia, using the commercial species Hediste diversicolor (Müller, 1776) as a model. This species belongs to the family Nereididae, found in estuarine environments along the European Atlantic coast (DOI 10.11646/zootaxa.5696.1.2). This species has several appendages with sensory functions along the body that help the animal navigate in its environment. It also has specialised feeding structures in the peristomium that are essential for taxonomic identification, called paragnaths. The parapodium has distinct chaetal arrangements that distinguish it from other species in the same genus. Due to the importance of economic activities such as fishing and aquaculture, this ragworm is a typical protagonist for studies in multiple areas, with a well-documented life cycle. However, knowledge is lacking on the growth and evolution of individual structures and appendages of the body in this species during its life cycle. Our findings revealed a significant positive correlation between the number of chaetiger segments and most of the morphological structures analysed, evidencing a proportional growth of most of these features, related directly to the chaetigers segments. Simple chaetae, a specific type of chaeta only present in the genus Hediste, were only found in individuals with more than 25 chaetiger segments, possibly indicating a functional change as the worm matures. Simple chaetae tend to be found earlier along the body axis, closer to the median chaetiger as the organism matures. The results illustrate how H. diversicolor develops over time, highlighting the developmental processes and representing the first biometric study of nereidid polychaetes, based on chaetiger count as a proxy for biometric growth, to define new possible life cycle stages, for supporting aquaculture purposes and other research fields.

POLYCHAETA Phyllodocida - Nereididae Ragworms and Allies Phyllodocidae Eulalia microphylla New Zealand Paddle Worm Sabellida - Serpulidae Spirobranchus cariniferus Blue Tube Worm Serpulid...

Background: Restorative regeneration, the capacity to reform a lost body part following amputation or injury, is an important and still poorly understood process in animals. Annelids, or segmented worms, show amazing regenerative capabilities, and as such are a crucial group to investigate. Elucidating the molecular mechanisms that underpin regeneration in this major group remains a key goal. Among annelids, the nereididae Platynereis dumerilii (re)emerged recently as a front-line regeneration model. Following amputation of its posterior part, Platynereis worms can regenerate both differentiated tissues of their terminal part as well as a growth zone that contains putative stem cells. While this regeneration process follows specific and reproducible stages that have been well characterized, the transcriptomic landscape of these stages remains to be uncovered. Results: We generated a high quality de novo Reference transcriptome for the annelid Platynereis dumerilii . To do so, we produced and analyzed three RNA-sequencing datasets, encompassing five stages of posterior regeneration, along with blastema stages and non-amputated tissues as controls. We included these regeneration RNA-seq datasets, as well as embryonic and tissue-specific datasets from the literature to produce a Reference transcriptome. We used this Reference transcriptome to perform in depth analyzes of RNA-seq data during the course of regeneration to reveal the important dynamics of the gene expression, process with thousands of genes differentially expressed between stages, as well as unique and specific genes expression at each regeneration stage. The study of these genes highlighted the importance of the nervous system at both early and late stages of regeneration, as well as the enrichment of RNA-binding proteins (RBPs) during almost the entire regeneration process. Conclusions: In this study, we provided a high-quality de novo Reference transcriptome for the annelid Platynereis that is useful for investigating various developmental processes, including regeneration. Our extensive stage-specific transcriptional analysis during the course of posterior regeneration shed light upon major molecular mechanisms and pathways, and will foster many specific studies in the future. ### Competing Interest Statement The authors have declared no competing interest.