Abstract
Pelagia noctiluca is considered the most important jellyfish in the Mediterranean Sea, due to its abundance and the severity of its stings. Despite its importance in marine ecosystems and the health problems caused by its massive arrival in coastal areas, little is known about its early life stages and its cnidome has never been described. This study of the morphological and anatomical features throughout the life cycle identifies four early stages: two ephyra and two metaephyra stages. Ephyra stage 1, newly developed from a planula, has no velar canals, gastric filaments or nematocyst batteries. Ephyra stage 2, has velar canals, a cruciform-shaped manubrium and gastric filaments. Metaephyra stage 3 has eight tentacle buds and nematocyst clusters for the first time. Lastly, in metaephyra stage 4, the eight primary tentacles grow nearly simultaneously, with no secondary tentacles. Complete nematocyst battery patterns gradually develop throughout the later life stages. Four nematocyst types are identified: a-isorhiza, A-isorhiza, O-isorhiza and eurytele. Of these, a-isorhiza and eurytele are the most important throughout the entire life cycle, while A-isorhiza and O-isorhiza have a more important role in advanced stages. All nematocysts show a positive correlation between increasing capsule volumes and increasing body diameter of the ephyrae, metaephyrae, young medusae and adult medusae. In the early stages, the volumes of euryteles in the gastric filaments are larger than those in the exumbrella, indicating that the capsule volume is critical in the absence of marginal tentacles, specialized for feeding. This study provides updated information, the most extensive description to date, including high-resolution photographs and schematic drawings of all the developmental stages in the life cycle of P. noctiluca. Additionally, the first cnidome characterization is provided for each stage to facilitate accurate identification of this species when collected in the water column, and to raise awareness of the potential for human envenomation.
Highlights
The presence of jellyfish blooms has a negative effect on human activities (Purcell et al, 2007) and causes socio-economic and public health problems worldwide (Gili and Pagès, 2005; Purcell et al, 2007; Kingsford et al, 2018)
The fourth nematocyst type was classified as a heterotrichous microbasic eurytele, based on the shaft with a clear enlargement of the basal tubule (Figure 2C, red arrow), and a distal dilation armed with prominent spines of different sizes and shapes, in contrast to the smaller spines on the tubule (Figures 2H,I, red arrows)
Four nematocyst types are identified during the life cycle: a-isorhiza, A-isorhiza, O-isorhiza and eurytele
Summary
The presence of jellyfish blooms has a negative effect on human activities (Purcell et al, 2007) and causes socio-economic and public health problems worldwide (Gili and Pagès, 2005; Purcell et al, 2007; Kingsford et al, 2018). Cnidocytes contain subcellular capsules called cnidocysts, which can be classified into three main categories: nematocyst, spirocyst and ptychocyst (Mariscal, 1974; Watson and Wood, 1988). The categories of spirocyst and ptychocyst each comprise a specific cnidocyst type, but over thirty different cnidocyst types are classified as nematocysts (Mariscal, 1974), some of which, due to capsule size and shape, tubule length and pattern, including spines, can be differentiated into subtypes (Östman, 2000). The cnidome, the term for the total complement of cnidocytes within a cnidarian specimen (Heins et al, 2015), including their cnidocyst size, abundance and distribution during each developmental life stage, is essential in taxonomic descriptions (Weill, 1934; Calder, 1983; Östman, 2000; Fautin, 2009). Advances in microscopic observation techniques have revealed errors in the traditional nomenclature (Östman, 2000), the need to re-examine and reclassify some cnidocytes
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
