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Algae and fungi found inside the coelenterons. (A) Oedogonium sp. (B) Epithemia sorex. (C) Cosmarium formosulum. (D) and (Ñ) Synedra acus. (E) Navicula sp. (F) Synedra ulna. (G) Class Hyphomycetes. (H) Nitzschia tryblionella. (I) Scenedesmus quadricauda. (J) Nitzschia filiformis. (K) Cocconeis placentula and Rhoicosphenia abbreviata. (L) Gomphonema constrictum. (LL) Scenedesmus falcatus. (M) C. placentula, Cyclotella meneghineana and Navicula zanoni. (N) Order Zygnematales.
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Hydra is a genus of common, sessile, solitary freshwater cnidarians, which are defined as carnivorous
and efficient predators. The purpose of this study was to obtain information on the feeding habits
and diet of Hydra vulgaris collected from its natural habitat in Nahuel Rucá Lake (Buenos Aires
Province, Argentina). We found three categories of fo...
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Citations
... The medusae are generally planktonic; however, some colonies of polyps are also, for example, members of the family Porpitidae, genus Porpita (Calder 2010). These hydrozoans in marine and freshwater ecosystems are predators of phytoplankton and zooplankton groups (Wintzer et al. 2011, Deserti et al. 2017, Di Camillo et al. 2017. The presence of these hydrozoans can be helpful in nature and human wellbeing because they reflect the conservation status of the marine ecosystem and are bioindicators of hydrographic conditions (Bieri 1977, Edwards 2012, Yilmaz et al. 2020. ...
Access to digital technology and software allows the production of a significant amount of biodiversity data, including citizens' species records, combined with field monitoring and standardized surveys, which are valuable to biological sciences; these data can help to know the distribution of organisms like medusozoans. We compiled records of the presence of Porpita porpita from open-access databases, scientific articles, and field observations to know their current distribution on the Mexican Atlantic for the first time. The yearly records of P. porpita increased over time, adding up to 22 records, of which 18 were assigned to citizen science. Most records correspond to 2011-2022, from April to May, and the Veracruz and Quintana Roo states. The records of the species in warm months and states with long shores can be related to an increase in touristic activities and observations by citizens. On the Mexican Atlantic, it is suggested that the use of digital technological devices under citizen science practices for recording P. porpita and its compilation in open-access databases acts as the principal method for tracking the distribution of this species. This work evidenced the need for a solid research framework of knowledge for P. porpita in the Mexican Atlantic, and future research could combine citizen science records and fieldwork records and improve the relationship between biological and oceanographic data to understand their spatial-temporal distribution patterns.
... Another major lesson from the hydra experiments comes from wild individuals, since this experiment in fact simulated a dietary evolutionary mismatch. Indeed, hydras in the wild consume freshwater crustaceans [55], but not artemia which live in brackish ecosystems. Moreover, it is unlikely that a similar high-abundance and frequent diet as the one we used would be found in the wild. ...
Cancer is a disease that affects the control of cell proliferation in many multicellular lineages. Nonetheless, little is known about the extent of conservation of the biological traits and ecological factors that promote or inhibit tumorigenesis across the metazoan tree. Particularly, changes in food quantity and quality have been linked to increased cancer incidence in humans, an outcome of evolutionary mismatch. Here, we apply evolutionary ecology principles to test the hypothesis whether food availability, regardless of the multicellular lineage considered, should govern tumorigenesis. We used two phylogenetically unrelated model systems, namely the cnidarian Hydra oligactis and the fish Danio rerio to investigate the impact of resource availability on tumor emergence and progression. Individuals from healthy and tumor-prone lines were placed on four diets that differed in feeding frequency and quantity. For both models, frequent overfeeding favored tumor emergence, while lean diets appear more protective. When investigating tumor progression, high food availability promoted it, whereas low resources controlled it, but without curing the animals. We discuss our results in light of current ideas about the possible conservation of basic processes governing cancer in metazoans (including ancestral life history trade-offs at the cell level) and in the framework of evolutionary medicine.
... Because of the presence of these asexual individuals, H. oligactis can reach huge population densities during late winter and early summer (Bryden, 1952; J.T. personal observation). This, in turn, could have major consequences for the population dynamics of their prey (mainly cladocerans and copepods, but also small fish; Cuker & Mosley, 1981;Deserti et al., 2017;Elliot et al., 1997;Massaro et al., 2013;Rivera-de la Parra et al., 2016;Schwartz et al., 1983) in a manner that amplifies with climate change. However, whether warming temperatures affect sexual or asexual fitness, and thereby population dynamics in hydra is still unclear. ...
Temperature is a key abiotic factor controlling population dynamics. In facultatively sexual animals inhabiting the temperate zone, temperature can regulate the switch between asexual and sexual modes of reproduction, initiates growth or dormancy, and acts together with photoperiod to mediate seasonal physiological transitions. Increasing temperature due to recent global warming is likely to disrupt population dynamics of facultatively sexual animals because of the strong temperature dependence of multiple fitness components. However, the fitness consequences of warming in these animals are still poorly understood. This is unfortunate since facultatively sexual animals-through their ability for asexual reproduction resulting in quick population growth and sexual reproduction enabling long-term persistence-are key components of freshwater ecosystems. Here, I studied the fitness effects of warming in Hydra oligactis, a freshwater cnidarian that reproduces asexually throughout most of the year but switches to sexual reproduction under decreasing temperatures. I exposed hydra polyps to a simulated short summer heatwave or long-term elevated winter temperature. Since sexual development in this species is dependent on low temperature, I predicted reduced sexual investment (gonad production) and elevated asexual fitness (budding) in polyps exposed to higher temperatures. The results show a complex effect of warming on sexual fitness: While gonad number decreased in response to warming, both male and female polyps exposed to high winter temperature were capable of multiple rounds of gamete production. Asexual reproduction and survival rate, on the contrary, clearly increased in response to higher temperature, especially in males. These results predict increased population growth of H. oligactis in temperate freshwater habitats, which will likely affect the population dynamics of its main prey (freshwater zooplankton), and through that, the whole aquatic ecosystem.
... Also, given that microbiota is altered in the tumorous polyps, and that the microbiota alters the behavior of hydras (Murillo-Rincon et al., 2017), we cannot exclude that a modified neuronal activity and feeding behavior might be responsible for the more efficient predation of tumorous polyps. We particularly emphasize here that the higher predation capacity of tumorous hydras was observed in both feeding conditions, ad libitum and restricted feeding, whereby the limited food supply is likely the more natural condition for hydras (Deserti et al., 2017). In any case, these results suggest that the level of resources could influence the coexistence between tumorous and non-tumorous individuals in a non-expected manner. ...
Tumors form as a result of abnormal and uncontrolled proliferation of cells within a multicellular organism, which can lead to cancer. Although this phenomenon exists in all metazoans, most research has focused on malignancies in humans and domestic animals. Thus, the evolutionary ecology of host-tumor interactions and their consequences for ecosystem functioning is a virtually untouched area of research.
To address these scientific questions, the biological model used in this thesis is a freshwater cnidarian, the brown hydra hydra oligactis, some of whose laboratory lines harbor tumors with notable specificities. In addition to the fact that the benign/malignant status of these tumors is not clear, they are capable of vertical transmission, during asexual reproduction of their host by budding. Furthermore, tumorous hydras have an increased number of tentacles compared to healthy hydras.
This thesis is organized in 5 sections, an introduction with two synthesis articles, three chapters presenting the research done and a general discussion. The first synthesis deals with the comparison between benign and malignant tumors, the second one deals with the costs of anticancer defenses in host organisms.
Our research on H. oligactis first described spontaneous tumors within several wild-type lineages (Chapter 1). This work shows that brown hydra tumors always appear to be of germline origin.
Moreover, we show that the presence of a bacterial species of the order Chlamydiales, could play a role in the initiation and/or maintenance of these tumor processes.
We then studied (chapter 2) the impact of the tumor-bacterial transmissible complex (i.e. tumor cells and bacteria) on the life history traits of the hydra host. This work shows that polyps derived from tumorous parents, prior to becoming tumoral themselves, intensify their sexual and asexual reproductive e�orts. Moreover, these tumorous polyps subsequently have a reduced survival compared to healthy ones. The adaptive nature of these life history trait changes, for the host and/or for the transmissible tumor cells, is discussed. This chapter also focuses on the origin of the increased number of tentacles in tumor polyps. By transplanting di�erent tumors into hydras of varying genetic background, we showed that polyps developing supernumerary tentacles after transplantation were always those that had received tumor tissue from hydras lines harboring transmissible tumors, and already associated with the appearance of supernumerary tentacles in their original host. Rather than a compensatory response initiated by the host, the growth of supernumerary tentacles in some tumor-bearing hydras would therefore be induced by transmissible
tumor cells.
Finally, in order to improve our understanding of the ecological consequences of host-tumor interactions on ecosystem functioning, we experimentally explored (Chapter 3) the relationships that tumor-bearing hydras have with other animal species living in aquatic environments. We demonstrated that, compared to healthy hydras, tumorous ones had an increased risk of predation by fish, a higher rate of colonization by commensal ciliates, and their ability to capture prey was superior due to their increased number of tentacles.
Taken together, this work argues for a better consideration of tumor processes in evolutionary ecology, both in terms of the ecological and evolutionary trajectory of host species and the consequences of these interactions on ecosystem functioning.
... Also, given that microbiota is altered in the tumorous polyps, and that the microbiota alters the behavior of hydras (Murillo-Rincon et al., 2017), we cannot exclude that a modified neuronal activity and feeding behavior might be responsible for the more efficient predation of tumorous polyps. We particularly emphasize here that the higher predation capacity of tumorous hydras was observed in both feeding conditions, ad libitum and restricted feeding, whereby the limited food supply is likely the more natural condition for hydras (Deserti et al., 2017). In any case, these results suggest that the level of resources could influence the coexistence between tumorous and non-tumorous individuals in a non-expected manner. ...
While it is often assumed that oncogenic processes in metazoans can influence species interactions, empirical evidence is lacking. Here, we use the cnidarian Hydra oligactis to experimentally explore the consequences of tumor associated phenotypic alterations for its predation ability, relationship with commensal ciliates and vulnerability to predators. Unexpectedly, hydra's predation ability was higher in tumorous polyps compared to non-tumorous ones. Commensal ciliates colonized preferentially tumorous hydras than non-tumorous ones, and had a higher replication rate on the former. Finally, in a choice experiment, tumorous hydras were preferentially eaten by a fish predator. This study, for the first time, provides evidence that neoplastic growth has the potential, through effect(s) on host phenotype, to alter biotic interactions within ecosystems and should thus be taken into account by ecologists.
... Horizontal transfer events may occur through intermediate species which are most of the time not sampled making more difficult to fully reveal the HTT network. On the one hand, the cnidarian Hydra vulgaris, the fly Drosophila willistoni and the coleopteran Sitophilus oryzae have geographic overlap with D. (L.) schiffleri (Corrêa et al. 2013;Garcia-Lauer et al. 2014;Deserti et al. 2017), but no currently known ecological interactions. In contrast, some species lack geographic contact and direct niche sharing with D. (L.) schiffleri. ...
Transposable elements (TEs) are mobile DNA sequences that are able to move from one genomic location to another. These selfish elements are known as genomic parasites, since they hijack the host molecular machinery to generate new copies of themselves. The mobilization of TEs can be seen as a natural mutagen because new TE copies can insert into different loci and impact host genomic structure through different mechanisms. Although our knowledge about TEs is improving with new genomes available, there is still very limited data about the mobilome of species from the Coleoptera order, the most diverse order of insects, including species from the Scarabaeidae family. Therefore, the main goal of this study was to characterize the mobilome of D. (Luederwaldtinia) schiffleri, based on low-coverage genome sequencing, and reconstruct their evolutionary history. We used a combination of four different approaches for TE characterization and maximum likelihood phylogenetic analysis to study their evolution. We found a large and diverse mobilome composed of 38 TE superfamilies, 20 DNA transposon and 18 retrotransposons, accounting for 21% of the genome. Moreover, we found a number of incongruences between the TE and host phylogenetic trees in three DNA transposon TE superfamilies, which represents five TE families, suggesting possible horizontal transfer events between highly divergent taxa. In summary, we found an abundant and diverse mobilome and a number of horizontal transfer events that have shaped the evolutionary history of this species.
... Due to the importance of such research, many studies regarding feeding aspects in Cnidaria have been conducted [21]. For example, several studies have been carried out on feeding and trophic performances in Medusozoa (e.g., [22][23][24]), including freshwater species [25], due to their impacts on commercial marine and freshwater species [5]. Although members of Anthozoa also have great ecological importance, as they help in the maintenance of aquatic ecosystems [26], fewer feeding-related studies have been performed on this class. ...
In this study, we performed a bibliographical review examining the scientific literature on "feeding in Anthozoa" for the period from 1890 to 2019, using the scientific database Google Scholar, supplemented with additional literature. This study categorized published scientific papers on this topic by decade of publication, target taxa, variability of species studied in each order and main themes studied. As a result, 153 studies were found, and based on their content, it was observed that within Anthozoa, there has been a concentration of feeding studies on species in the orders Actiniaria (Hexacorallia), Scleractinia (Hexacorallia), and Alcyonacea (Octocorallia). This indicates that the other remaining orders of the group have been comparatively neglected with regards to their feeding aspects. Therefore, as data on feeding in some groups of Anthozoa are scarce, studies need to be carried out to fill the gaps that permeate this important benthic group, in order to better understand their ecology.
... Aquatic cnidarians and terrestrial insects sharing mutual parasites or viruses appears to be unlikely, given their approximately 600 million year divergence time and different habitats. Terrestrial insect larvae or imagos which fall into the water column may be preyed upon by Hydra, which are known to feed upon dipteran larvae and can engulf prey items in excess of 30mm in length [59]. As Teleopsis species, as well as members of other diopsid genera, often live over bodies of water [29,30,60] opportunistic predation may potentially allow diopsid mariner DNA to be taken up by Hydra cells resulting in horizontal transfer. ...
The stalk-eyed flies (Diopsidae, Diptera) are a family of approximately 100 species of calypterate dipterans, characterised by extended head capsules. Species within the family have previously been shown to possess six subfamilies of mariner transposons, with nucleotide substitution patterns suggesting that at least two subfamilies are currently active. The vertumnana subfamily has been shown to have been involved in a horizontal transfer event involving Diopsidae and a second dipteran family in the Tephritidae. Presented here are cloned and sequenced mariner elements from three further diopsid species, in addition to a bioinformatic analysis of mariner elements identified in transcriptomic and genomic data from the genus Teleopsis. The newly identified mariner elements predominantly fall into previously recognised subfamilies, however the publicly available Teleopsis data also revealed a novel subfamily. Three of the seven identified subfamilies are shown to have undergone horizontal transfer, two of which appear to involve diopsid donor species. One recipient group of a diopsid mariner is the Bactrocera genus of tephritid flies, the transfer of which was previously proposed in an earlier study of diopsid mariner elements. The second horizontal transfer, of the mauritiana subfamily, can be traced from the Teleopsis genus to the cnidarian Hydra vulgaris. The mauritiana elements are shown to be active in the recipient H. vulgaris and transposase expression is observed in all body tissues examined in both species. The increased diversity of diopsid mariner elements points to a minimum of four subfamilies being present in the ancestral genome. Both vertical inheritance and stochastic loss of TEs have subsequently occurred within the diopsid radiation. The TE complement of H. vulgaris contains at least two mariner subfamilies of insect origin. Despite the phylogenetic distance between donor and recipient species, both subfamilies are shown to be active and proliferating within H. vulgaris.
... En su papel como predadores en las comunidades bentónicas Schwartz et al. (1983) señalan a los crustáceos del plancton como sus presas principales, así como a los gusanos oligoquetos. Deserti et al. (2017) recogen la presencia de un amplio espectro de micro-invertebrados, hongos y microalgas en la cavidad gastrovascular de H. vulgaris. El ataque de H. oligactis sobre un oligoqueto se muestra en la Fig. 3. -Microfotografías del cnidoma de Hydra oligactis. ...
Se describe la presencia de cuatro taxones de hidras de agua dulce (Cnidaria, Hydrozoa: Hydridae) en zonas someras epicontinentales de la cuenca del Duero (NO de España). En la subcuenca del Tera se encontraron individuos aislados sobre macrófitos sumergidos de tres taxones: Hydra vulgaris Pallas, 1766, Hydra (Pelmatohydra) oligactis Pallas, 1766 e Hydra (Chlorohydra) viridissima Pallas, 1766, y además en el Carrión grupos coloniales sobre bloques de cuarcita de la forma H. vulgaris var. aurantiaca Ehrenberg, 1838. En todos los casos se corresponde con ecosistemas de media montaña de aguas frías, transparentes y oligotróficas, de pH ligeramente ácido y con escasa mineralización. Todas las especies fueron localizadas en simpatría estricta, aunque en el lago de Sanabria se pudo citar tres taxones en diferentes hábitats. Se documenta la predación en cautividad de H. oligactis sobre gusanos oligoquetos y los periodos de formación de pólipos por gemación.
The feeding upon large animals—even larger than the predator—by benthic cnidarians has been reported from many ecosystems but never exhaustively studied to date. By reviewing 38 papers on this topic, this review aims to recap the observations on the predatory behaviour of polyps, to establish feeding plasticity boundaries and to understand the contribute of this trophic strategy to the benthic–pelagic coupling. The reviewed documents published increasingly during the last two decades mostly reported observations on heterotrophic Anthozoa in shallow ecosystems collected through photo/video records. The main prey items are represented by gelatinous zooplankton and echinoderms. The lexical discordance in the considered papers highlights the need to standardize the terminology to describe the feeding behaviour of benthic Cnidaria, opportunistic and characterized by a strong plasticity. Given the importance of large prey in cnidarian trophism, we proposed an unambiguous terminology that will help the online search of literature and address future studies. We suggest identifying micro-predation (predator/prey size ratio ≥ 5:1) and macro-predation (predator/prey size ratio is ≤ 1:1) as distinct feeding modalities, because the capture of large prey involves peculiar movements of polyps, such as stretching and retracting of column and tentacles to pull the prey towards the mouth.
