Cnidome and Morphological Features of Pelagia noctiluca (Cnidaria: Scyphozoa) Throughout the Different Life Cycle Stages

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.

Successful Culture of Pelagia noctiluca (Cnidaria: Scyphozoa) Over Time: A Continuous Supply of the Holoplanktonic Jellyfish for Research and Industrial Applications

“…The mauve stinger Pelagia noctiluca is an oceanic jellyfish, widely distributed in the open waters of the Mediterranean Sea (Mariottini et al, 2008;Canepa et al, 2014;Marambio et al, 2021). The lack of a polyp phase, a peculiarity within its life cycle (Sandrini and Avian, 1983;Helm, 2018;Ballesteros et al, 2021b), allows it to inhabit oceanic as well as coastal ecosystems (Canepa et al, 2014). This scyphozoan is considered the most important jellyfish in the Mediterranean basin; its massive outbreaks and the high toxicity of its venom (Mariottini et al, 2008) lead to serious negative effects on tourism, fisheries, aquaculture, and the energy industry (Canepa et al, 2014;Bosch-Belmar et al, 2020).…”

Trial Assay for Safe First-Aid Protocol for the Stinging Sea Anemone Anemonia viridis (Cnidaria: Anthozoa) and a Severe Toxic Reaction

“…The nematocyst category is the most varied. Up to thirty types, with different capsule morphologies and tubule patterns, are capable of catching and entangling prey and acting as defense against predators [2,4,5]. Differing from nematocysts, the spirocyst and ptychocyst categories are composed of a single type of cnidocyst each [2].…”

“…Five different morphotypes of A. viridis and four cryptic species have been described to date [25]. The cnidome, which includes the total complement of cnidocysts within a cnidarian specimen [4,5], comprises four types in adult individuals collected in the North Adriatic Sea; three nematocysts (holotrichous isorhiza, p-mastigophore, and a possible microbasic b-mastigophore) and one spirocyst [26]. Envenomation from sea anemones usually involves mild signs and symptoms of erythema, irregular, and painful plaques and papules [17,20,27,28]; rarely, cases of A. viridis stings have been reported [17,20].…”

Trial Assay for Safe First-Aid Protocol for the Stinging Sea Anemone <em>Anemonia viridis</em> (Cnidaria: Anthozoa) and a Severe Toxic Reaction

“…The nematocyst category is the most varied. Up to thirty types, with different capsule morphologies and tubule patterns, are capable of catching and entangling prey and acting as defence against predators [2,4,5]. Differing from nematocysts, the spirocyst and ptychocyst categories are composed of a single type of cnidocyst each [2].…”

“…Five different morphotypes of A. viridis and four cryptic species have been described to date [25]. The cnidome, which includes the total complement of cnidocytes within a cnidarian specimen [5], comprises four cnidocyte types in adult individuals collected in the North Adriatic Sea; three nematocysts (holotrichous isorhiza, p-mastigophore and a possible microbasic bmastigophore) and one spirocyst [26]. Envenomation from sea anemones usually involves mild signs and symptoms of erythema, irregular and painful plaques and papules [17,20,27,28]; rarely, cases of A. viridis stings have been reported [17,20].…”