Ultrastructure of the extensively developed nuchal organs of <i>Laonice bahusiensis</i> (Annelida: Canalipalpata: Spionidae)

Jelsing, Jacob; Eibye‐Jacobsen, Danny

doi:10.1002/jmor.10813

Cited by 4 publications

(3 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, in adult specimens, the size and morphology of the caruncle varies among species (Radashevsky & Hsieh ). The caruncle bears ciliated nuchal organs with sensory cilia traversing an olfactory chamber located beside the caruncle (Purschke ; Jelsing & Eibye‐Jacobsen ). The nuchal organs, which are also directly innervated from the brain, can generate water currents and promote a rapid exchange of sensory stimuli (Purschke ).…”

Section: Discussionmentioning

confidence: 99%

Anterior sensory organs in Sabellariidae (Annelida)

Faroni-Perez

Helm

Burghardt

et al. 2016

Invertebrate Biology

View full text Add to dashboard Cite

Sensory organs in Annelida are very diverse and may be useful for assessments of morphological adaptation and character evolution. We used several methods to provide new insights into processes underlying the evolutionary radiation of anterior sensory organs in Sabellariidae. The presence and morphological diversity of the median organ (MO) found in the group was reviewed in order to test its phylogenetic significance and possible relationships to the distribution and ecological traits of the lineages. To test the intraspecific phenotypic plasticity of the MO, molecular analyses were conducted that focused on mitochondrial and nuclear genes from populations of Idanthyrsus australiensis exhibiting variation in the morphology of the MO. We used an integrative microscopical study of the ontogeny of Sabellaria alveolata to describe the anterior sensory structures present in the larvae and the morphological changes occurring before, during, and after settlement. In larval stages, the palps and the dorsal hump (DH) exhibit distinct innervation. The larval DH organ, which is likely to play a major role in chemoreception for settlement, is interpreted as being the incipient form of the adult MO. These results suggest that annelid sensory organs including the MO may be useful for phylogenetic and developmental investigations.Additional key words: chemoreception, gregarious settlement, marine invertebrates, polychaetes, radiation of lineages Invertebrate Biology 135(4): 423-447.

show abstract

Section: Discussionmentioning

confidence: 99%

Anterior sensory organs in Sabellariidae (Annelida)

Faroni-Perez

Helm

Burghardt

et al. 2016

Invertebrate Biology

View full text Add to dashboard Cite

show abstract

“…A common morphological feature of all these enlarged nuchal organs is their elongated bands of cilia forming semicircles, circles, ovals, or even long parallel bands on either side of the body (Beckers & Tilic, 2021;Jelsing, 2003;Jelsing & Jacobsen, 2010;Söderström, 1930). These large nuchal organs are typically called caruncles when situated on a bulging ridge and nuchal epaulets on flat structures (Beckers & Tilic, 2021;Purschke, 1997Purschke, , 2005.…”

Section: Nuchal Organsmentioning

confidence: 99%

“…In contrast to the external variability of nuchal organs, their anatomical structure is almost identical, comprising only a few but highly similar cell types throughout all taxa investigated (Buhre & Purschke, 2021;Purschke, 1997Purschke, , 2005Verger-Bocquet, 1992). These organs comprise ciliated supporting cells, bipolar primary receptor cells, a retractor muscle (if they can be retracted), and direct innervation from the brain's posterior region (Buhre & Purschke, 2021;Helm et al, 2018b;Jelsing & Jacobsen, 2010;Purschke, 1997Purschke, , 2005Purschke, , 2016Rullier, 1951;Schmidtberg & Dorresteijn, 2010;Verger-Bocquet, 1992). The supportive and receptor cells form an olfactory chamber separated from the exterior that houses the sensory processes.…”

Section: Nuchal Organsmentioning

confidence: 99%

Development and structure of the anterior nervous system and sense organs in the holopelagic annelid Tomopteris spp. (Phyllodocida, Errantia)

Purschke

Helm

2023

Org Divers Evol

View full text Add to dashboard Cite

Tomopteridae are transparent, predatory Annelida inhabiting pelagic ocean zones. Despite being well-known for their fast metachronal swimming and species-specific bioluminescence, our knowledge of morphological adaptations in these fascinating holopelagic worms remains extremely limited. In particular, the evolutionary scenarios and adaptive changes related to the transition from putative benthic ancestors to recent free-swimming groups remain poorly investigated and understood. Therefore, we investigated different taxa and developmental stages within the holopelagic Tomopteridae. We used a comparative morphological approach, including a range of microscopic methods, in our investigations focused on the anterior nervous system and prominent sensory structures, such as nuchal organs and tentacular cirri, in early developmental and adult stages of four tomopterid species. Our data show that Tomopteridae undergo heterochronic, lecithotrophic development with early visibility of adult-like features, which is consistent with earlier investigations. Furthermore, our ultrastructural examinations of the tomopterid nuchal organ highlight the conservativism in the fine structure and development of this prominent polychaete chemosensory organ. Nevertheless, our data indicate ultrastructural differences, such as an extraordinary number of supporting cell types and a bipartite olfactory chamber, potentially related to their pelagic lifestyle. In contrast to previous assumptions, it is shown that the supporting structures in the cirrus-like appendages of the first chaetiger contain prominent intracellular skeletal elements rather than annelid chaetae. These findings highlight the need for further investigations to understand Annelida’s immense morphological diversity of organ systems. Furthermore, our data demonstrate the necessity of functional analyses to understand Annelida’s adaptive radiation of sensory and neuronal structures.

show abstract

Ultrastructure and functional morphology of the dorsal organs in Scoloplos armiger (Annelida, Sedentaria, Orbiniida)

Buhre

Purschke

2021

Zoomorphology

View full text Add to dashboard Cite

Annelids and particularly polychaetes possess a great variety of sensory organs and respond to numerous sensory stimuli. Although eyes and nuchal organs are comparatively well studied, the so-called dorsal organs are among the lesser-known sense organs in aquatic annelids. Moreover, they are known to be restricted to only two out of approximately 80 families of polychaetes—Orbiniidae and Spionidae—which are not closely related. These organs have been regarded as segmentally repeated nuchal organs in the latter taxon, but in Orbiniidae, data are lacking, although it is known that the organs occur almost along the entire trunk except for the anterior-most segments. Furthermore, although the nuchal organ ultrastructure is known to be comparatively uniform for many polychaete species, a comparative investigation has not been conducted in Orbiniidae. To bridge this data gap, we examined an intertidal population of the widely distributed species Scoloplos armiger. Although not completely identical, nuchal and dorsal organs show a high degree of correspondence in the examined specimens. Moreover, both organs correspond to the general structure of nuchal organs. They comprise ciliated supportive cells and bipolar receptor cells and are innervated directly from the brain. The supportive cells form subcuticular spaces and olfactory chambers apically protected by specialized microvilli that house the sensory processes—cilia and microvilli—of the monociliated receptor cells. Therefore, it can be concluded that nuchal and dorsal organs are also identical in Orbiniidae. However, despite general correspondence with spionids, convergent evolution in the two taxa appears to be the most parsimonious interpretation.

show abstract

Ultrastructure of the extensively developed nuchal organs of Laonice bahusiensis (Annelida: Canalipalpata: Spionidae)

Cited by 4 publications

References 16 publications

Anterior sensory organs in Sabellariidae (Annelida)

Anterior sensory organs in Sabellariidae (Annelida)

Development and structure of the anterior nervous system and sense organs in the holopelagic annelid Tomopteris spp. (Phyllodocida, Errantia)

Ultrastructure and functional morphology of the dorsal organs in Scoloplos armiger (Annelida, Sedentaria, Orbiniida)

Contact Info

Product

Resources

About