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Lakshmanan, R.; Saravanan, R.; Kalidas, C.; Rajendran, P.; Babu, A.M.; Asha, P.S., and Joshi, K.K., 2024. Occurrence of the non-native mauve stinger, Pelagia cf. noctiluca, in coastal waters off Cape Comorin, southern Bay of Bengal. Journal of Coastal Research, 40(6), 1103–1110. Charlotte (North Carolina), ISSN 0749-0208. During a jellyfish survey in the southern Bay of Bengal, India, four scyphozoan jellyfish from the family Pelagiidae (Order: Semaeostomeae) were observed. The observed specimens were found at a depth of 1 to 2 m off the coast of Arockiapuram (8°05′ N, 77°11′ E), Cape Comorin (now Kanyakumari). The underwater photographic and video documentation with live colouration enabled the identification of the collected specimens as mauve stingers, Pelagia noctiluca (Forskal, 1775). The observed specimens have pink- or mauve-coloured hemispherical umbrellas with eight marginal tentacles that are transversely wrinkled and eight pear-shaped rhopalia. In general, P. noctiluca has a common distribution along the Atlantic Ocean, the Mediterranean Sea, and the Pacific Ocean; however, recordings of this species in Indian waters are considered rare and out of its documented distribution area. It has been reported earlier from Indian waters, and the nearest known distribution is from the Gulf of Mannar, Bay of Bengal. This species shows an invasive distribution in the warmer tropical environments due to its wide range of temperature tolerance. The species can be considered “invasive” as the periodic occurrence of large abundances in coastal waters occurs when this typically offshore species is advected shoreward in years when population densities appear to be exceptionally high. Consequently, it is problematic at the very periphery of its “natural range,” thus differing from truly invasive species that have been introduced into a new area. The findings in this study suggest that specific hydrodynamic conditions may transport the permanent offshore population of P. noctiluca inshore, resulting in non-native outbreaks on shores. The study sheds light on the presence of the non-native oceanic mauve stinger in the Cape Comorin coastal waters in the Bay of Bengal, which alters the fisheries and tourism industries because it has a negative interaction with human recreational and coastal fishing activities.

Recent development of environmental DNA (eDNA) analysis allows us to survey underwater macro-organisms easily and cost effectively; however, there have been no reports on eDNA detection or quantification for jellyfish. Here we present the first report on an eDNA analysis of marine jellyfish using Japanese sea nettle (Chrysaora pacifica) as a model species by combining a tank experiment with spatial and temporal distribution surveys. We performed a tank experiment monitoring eDNA concentrations over a range of time intervals after the introduction of jellyfish, and quantified the eDNA concentrations by quantitative real-time PCR. The eDNA concentrations peaked twice, at 1 and 8 h after the beginning of the experiment, and became stable within 48 h. The estimated release rates of the eDNA in jellyfish were higher than the rates previously reported in fishes. A spatial survey was conducted in June 2014 in Maizuru Bay, Kyoto, in which eDNA was collected from surface water and sea floor water samples at 47 sites while jellyfish near surface water were counted on board by eye. The distribution of eDNA in the bay corresponded with the distribution of jellyfish inferred by visual observation, and the eDNA concentration in the bay was ~13 times higher on the sea floor than on the surface. The temporal survey was conducted from March to November 2014, in which jellyfish were counted by eye every morning while eDNA was collected from surface and sea floor water at three sampling points along a pier once a month. The temporal fluctuation pattern of the eDNA concentrations and the numbers of observed individuals were well correlated. We conclude that an eDNA approach is applicable for jellyfish species in the ocean.

Ephyrae, the early stages of scyphozoan jellyfish, possess a conserved morphology among species. However, ontogenetic transitions lead to morphologically different shapes among scyphozoan lineages, with important consequences for swimming biomechanics, bioenergetics and ecology. We used high-speed imaging to analyse biomechanical and kinematic variables of swimming in 17 species of Scyphozoa (1 Coronatae, 8 “Semaeostomeae” and 8 Rhizostomeae) at different developmental stages. Swimming kinematics of early ephyrae were similar, in general, but differences related to major lineages emerged through development. Rhizostomeae medusae have more prolate bells, shorter pulse cycles and higher swimming performances. Medusae of “Semaeostomeae”, in turn, have more variable bell shapes and most species had lower swimming performances. Despite these differences, both groups travelled the same distance per pulse suggesting that each pulse is hydrodynamically similar. Therefore, higher swimming velocities are achieved in species with higher pulsation frequencies. Our results suggest that medusae of Rhizostomeae and “Semaeostomeae” have evolved bell kinematics with different optimized traits, rhizostomes optimize rapid fluid processing, through faster pulsations, while “semaeostomes” optimize swimming efficiency, through longer interpulse intervals that enhance mechanisms of passive energy recapture.

In order to investigate possible differences and patterns of body-plan morphogenesis among Scyphozoa, we described the morphology and development of the bell and oral arms of 11 species. We built a model for the development of the group and provide a guide for recognizing development stages. In general, the bell diameter was more efficient than age (days) to identify the stage of development, which suggests that the events of morphogenesis depend more on body size than on age. We used measurements of bell and oral arm to build growth curves and described the timing of developmental events (e.g., appearance of digitata, velar lappets and oral arms, filling of interlobe gaps) and patterns of morphogenesis (contour of marginal lappets, branching of oral arms, and presence of structures/appendages on the oral arms). The time until the appearance of digitata and velar lappets, the marginal lappet contour, and the presence of lateral folds in oral arms supported a phylogenetic relationship between the “Semaeostomeae” and Rhizostomeae (Dactyliophorae and Kolpophorae) lineages. “Semaeostomeae” jellyfish with digitata (family Ulmaridae) and differentiated velar lappets developed such structures at larger bell diameters than rhizostomes; only Dactyliophorae rhizostomes had serrated contour of the lappets; only species of Rhizostomeae showed development of the lateral folds; and only Ulmaridae and Rhizostomeae had differentiated appearance of the velar lappets. We propose a specific definition of oral arms that is based on morphological and functional features. Therefore, estimating development timing and describing the way that these structures develop can help to understand how jellyfish feeding strategies change during initial growth and how the changes in these structures can reflect the differences in feeding habits among the groups.

The Indo-Pacific is recognized as a hotspot for marine diversity. The taxonomy of certain taxa, such as Discomedusae jellyfish, has been neglected, despite its importance in the fishery industry. This study documents the first records of Discomedusae for the Java Sea using an integrative approach and provide notes about its distribution in the area. We used up to 53 morphological and meristic characters and amplified one mitochondrial marker (COI). The comparison and assessment of these data resulted in the recognition of seven species of Discomedusae, from which five has been recorded for the Indo-Pacific area. Two other species require a taxonomic revision to confirm the species assignation. The distribution of jellyfish in the coast of Java Sea might be correlated with the jellyfish life history and species-specific ranges of tolerance, and not solely determined by the environmental parameters. These findings provide the foundations for extending the taxonomic research in the area; the description of the biodiversity will increase the understanding of the population dynamics and its implications in the fisheries.

This study determined the complete mitochondrial genome of the jellyfish (Scyphozoa, Semaeostomeae) for the first time. The genome was a linear molecule of 16,390 bp in length and 59.3% AT. It comprised of 13 typical protein-coding genes ( and ), two ribosomal RNAs (16S and 12S rRNA), and two tRNAs ( and ). In addition, we detected two additional open reading frames ( and ) at one end of the genome. The gene-coding structures were identical to those of other scyphozoans. Based on a molecular phylogeny constructed using 13 protein-coding genes, has the closest genetic relationship with the genus (Semaeostomeae).

Leatherback turtles (Dermochelys coriacea) are obligate predators of gelatinous zooplankton. However, the spatial relationship between predator and prey remains poorly understood beyond sporadic and localized reports. To examine how jellyfish (Phylum Cnidaria: Orders Semaeostomeae and Rhizostomeae) might drive the broad-scale distribution of this wide ranging species, we employed aerial surveys to map jellyfish throughout a temperate coastal shelf area bordering the northeast Atlantic. Previously unknown, consistent aggregations of Rhizostoma octopus extending over tens of square kilometers were identified in distinct coastal \"hotspots\" during consecutive years (2003-2005). Examination of retrospective sightings data (>50 yr) suggested that 22.5% of leatherback distribution could be explained by these hotspots, with the inference that these coastal features may be sufficiently consistent in space and time to drive long-term foraging associations.

In this study, the complete mitogenome of brownbranded moon jellyfish Aurelia limbata (Cnidaria, Semaeostomeae, Ulmaridae) was sequenced and analyzed. The linear mitogenome is 16,953 bp long with 37.3% A, 16.8% C, 15.5% G, and 30.4% T nucleotide distributions. Total AT% content is 67.7%, which is the highest AT% content among available Aurelia species complete mitogenome records. Furthermore, phylogenetic relationships of A. limbata in the family Ulmaridae were investigated. According to protein-coding genes based phylogenetic tree, the A. aurita species collected from Korea water is the closest related species to A. limbata.

This manuscript presents four new observations of the jellyfish Mawia benovici in the Adriatic Sea. This new species was recently identified as Pelagia benovici by Piraino et al. (2014) and then placed in the new genus Mawia by Avian et al. 2016. This species is rare and is almost exclusively observed in the Adriatic Sea. Interestingly, the majority of observations refer to males only. Few studies have addressed the issue of sex determination in Syphozoa in particular, as sex identity can only be determined at the medusa stage. Unfortunately, the rarity of M. benovici and the lack of female specimens have so far prevented indispensable laboratory studies to clarify its life cycle. Still, we tried to propose an explanation for our field observations.

Aurelia spp. is a cosmopolite scyphozoan species and likely the most studied jellyfish in the world. Its pelagic–benthic life cycle is complex, and the benthic asexual reproducing stage (polyp) is acknowledged fundamentally in bloom onset. Despite this, field investigations remain scarce and are mainly restrained to the western Pacific Ocean. Thau lagoon (43°23′59.10″ N 3°36′37.15″ E), a semi-enclosed system that harbours a resident population of Aurelia sp., is in essence a natural laboratory that offers an ideal framework to investigate the life cycle of the species. We here used a non-destructive approach consisting on a field survey over the entire lagoon (ca. 7 ha) and several substrate types by free diving to examine the distribution and habitat use of Aurelia sp. benthic population. We show that polyps were largely distributed over the entire lagoon, settled mainly on artificial hard substrates, thereby stressing the promoting role of anthropogenic perturbations in coastal areas, i.e. habitat modification, for jellyfish proliferations. Therefore, our study suggest a potential increase in Aurelia sp. benthic populations as an outcome of mounting coastal constructions in the near future; the consequences of which ultimately might promote an increase in jellyfish outbreaks.