Spectral diversity among members of the green fluorescent protein family in hydroid jellyfish (Cnidaria,Hydrozoa)

The cDNAs encoding the genes of new proteins, homologous to the well-known Green Fluorescent Protein (GFP) from the hydroid jellyfish Aequorea victoria, were cloned. Two green fluorescent proteins from one unidentified anthomedusa, a yellow fluorescent protein from Phialidium sp., and a nonfluorescent chromoprotein from another unidentified anthomedusa were characterized. Thus, a broad diversity of GFP-like proteins among the organisms of the class Hydrozoa in both spectral properties and primary structure was shown.Translated from Bioorganicheskaya Khimiya, Vol. 31, No. 1, 2005, pp. 49–53.Original Russian Text Copyright © 2005 by Yanushevich, Shagin, Fradkov, Shakhbazov, Barsova, Gurskaya, Labas, Matz, K. Lukyanov, S. Lukyanov.     

Effects of salinity on the growth and morphology of the invasive,euryhaline hydroid Cordylophora (Phylum Cnidaria,Class Hydrozoa)

The invasive, euryhaline hydroid Cordylophora sp. is a colonial cnidarian present in both freshwater and brackish water habitats. Individuals contend with osmotic stress at the tissue and cellular level. It has been suggested that this hydroid's ability to expand its range of distribution by invading new habitats is due in large part to an ability to acclimate to new salinities. The purpose of this study was to assess colony growth and morphological changes at various salinities in freshwater and brackish genotypes of Cordylophora sp. Single genotypes from a known freshwater clade (0.5 psu; Des Plaines River) and a known brackish clade (16 psu; Napa River) were cultured and gradually transitioned to 12 different salinities ranging 0.5–22 psu, and we characterized the growth rates and hydranth morphological features at each salinity. Colony growth was optimal at 0.5 psu for the freshwater genotype and 10 psu for the brackish genotype. Changes in hydranth morphology in the freshwater genotype were primarily observed at higher salinities, while morphological changes in the brackish genotype primarily occurred at lower salinities. Our results for the brackish genotype generally concur with previous work, but this study is the first to document the response of a freshwater genotype of Cordylophora sp. to various salinities. Differences in growth between these two genotypes strongly support the previously proposed existence of multiple cryptic species. Furthermore, because this hydroid is quite prevalent in freshwater and brackish systems as a fouling organism, understanding the effects of various salinities on the successful establishment of Cordylophora sp. is an important contribution to the understanding of the ecophysiology and management of this invasive hydroid.     

Unexpected systematic affinities and geographic expansion of a marine alien hydroid (Cnidaria: Hydrozoa)

Biological systematics provides taxonomic information and expertise for biogeography and biological invasion research and management. However, the systematic classification of most taxa, including some alien and invasive species, relies only on morphology. This applies for example to Sertularella tongensis Stechow, 1919 Stechow, E. (1919). Zur Kenntnis der Hydroidenfauna des Mittelmeeres, Amerikas und anderer Gebiete, nebst Angaben über einige Kirchenpauer'sche Typen von Plumulariden. Zoologische Jahrbuecher (Systematik), 42, 1–172. [Google Scholar] (Cnidaria: Sertulariidae), an alien hydrozoan recently reported in the Mediterranean. Its genus affiliation is still unclear and controversial. Historically, it has been assigned to several existing genera. However, molecular data (COI, 16S, 18S, 28S) provided here do not support these previous assignments. Instead, integrative analyses combining morphological and molecular data support reassigning this species to a new genus, Bicaularia gen. nov. A biogeographic review revealed that this species is widely distributed in the mid- and low-latitude waters of the Indo-Pacific region, and is spreading to some tropical and temperate regions including the Mediterranean and Caribbean Seas, as well as Korea and Japan. This expansion may be attributable to human activity such as shipping through the Suez and the Panama Canals. However, the new record attached to a floating Sargassum algal fragment in the surface water of the open Pacific, might suggest a neglected cryptic spread pathway with the assistance of floating biological organisms. Our findings shed light on the complexity of the phylogeny and spread pathway of the investigated hydrozoan species. We regard the fine systematics as the first step towards future global sampling for molecular studies aiming to elucidate the origins and pathways for alien and invasive species.

http://zoobank.org/urn:lsid:zoobank.org: pub: 45AB0849-1E3B-477FB643-1B3B4603C1FF     

Nutritional physiology and colony form in Podocoryna carnea (Cnidaria: Hydrozoa)

Abstract. We compared growth rates and final morphological states of the athecate colonial hydroid Podocoryna carnea in two nutritional environments: one varying the quantity of food provided at a fixed interval and the second varying the time between feedings of a fixed quantity. In both environments, replicate colonies were either fed uniformly, or fed on only one side and starved on the other. In addition, we fed colonies fluorescence-labeled cultures of Artemia salina and documented the subsequent distribution of label. We found that both the growth rates and the final morphological state varied logarithmically with food supply. Heterogeneous feeding had a marked effect on colony morphology, with a sharp boundary in polyp number, stolon density, and polyp size forming at the fed–unfed interface. The distribution of fluorescence was correlated with sites of colony growth. These results confirm and extend early work on the priority of growth zones in colonial hydroids, and present new challenges for understanding the relationship among energy metabolism, gastrovascular circulation, and colony form.     

Medusoid release and spawning of Macrorynchia philippina Kirchenpauer, 1872 (Cnidaria,Hydrozoa,Aglaopheniidae)

The life cycle of the aglaopheniid Macrorynchia philippina Kirchenpauer, 1872, is re-described from examination of live specimens collected from Réunion Island, Indian Ocean. Fertile colonies were collected on the outer slope of the coral reef and medusoid release happened a few hours later. Video sequences were recorded. Colonies were hermaphroditic: each phylactocarp contained one female and one male gonotheca. Sexual dimorphism was remarkable: sex could be recognized by colour, the female being red ochre, including about 40 oocytes disposed in a mosaic feature, and the male yellow ochre, having a homogeneous mass of spermatozoa. The blastostyle ran all around the gonangium near the closure of the two valves of the gonotheca, forming gubernacula. A ring of refringent corpuscles was clearly visible near the apex. Medusoids were indistinguishable inside the gonotheca. Male and female medusoids were released simultaneously at gamete maturity. Medusoid release involved the basal rupture of the blastostyle and the rupture of the links between the ectoderm surrounded the medusoid (the mantle), including the blastostyle (the mantle), and the gonothecal perisarc. While the two valves of the gonotheca were pushed and drew aside, the medusoid emerged by slipping out of the mantle that ruptured distally, forming a sheath; the bell of the medusoid did not contract. Immediately after emergence, quick and strong contractions of the bell allowed the medusoid to swim and induced spawning by breaking the ectoderm surrounding the gametic mass around the spadix. Spawning lasted only a few minutes: both oocytes and spermatozoa were expelled at each contraction. Spent medusoids remained alive only about 2 h. External fertilization gave rise to planulae 1 day later.     

Ultrastructure of the calcium-sequestering gastrodermal cell in the hydroid Hydractinia symbiolongicarpus (Cnidaria, Hydrozoa)

Large, free-floating crystals of calcium carbonate occur in vacuoles of gastrodermal cells of the hydroid Hydractinia symbiolongicarpus. Here, morphological details about the process by which these cells accumulate and sequester calcium are provided by a cytochemical method designed to demonstrate calcium at the ultrastructural level. Electron-dense material presumably indicative of the presence of calcium was EGTA-sensitive and was shown by parallel electron energy loss spectroscopy (EELS) and energy spectroscopic imaging (ESI) to contain calcium. Calcium occurred in only one cell type, the endodermally derived gastrodermal cell. In these cells, the electron-dense material appeared first as a fine precipitate in the cytosol and nucleus and later as larger deposits and aggregates in the vacuole. During the life cycle, gastrodermal cells of the uninduced planula and the planula during metamorphic induction sequestered calcium. In primary polyps and polyps from established colonies, gastrodermal cells sequestered calcium, but the endodermal secretory cells did not. Our observations support the hypothesis that gastrodermal cells function as a physiological sink for calcium that enters the organism in conjunction with calcium-requiring processes such as motility, secretion, and metamorphosis.     

Serotonin-immunoreactive neural system and contractile system in the hydroid Cladonema (Cnidaria, Hydrozoa)

Serotonin is a widespread neurotransmitter which is present in almost all animal phyla including lower metazoans such as Cnidaria. Serotonin detected in the polyps of several cnidarian species participates in the functioning of a neural system. It was suggested that serotonin coordinates polyp behavior. For example, serotonin may be involved in muscle contraction and/or cnidocyte discharge. However, the role of serotonin in cnidarians is not revealed completely yet. The aim of this study was to investigate the neural system of Cladonema radiatum polyps. We detected the net of serotonin-positive processes within the whole hydranth body using anti-serotonin antibodies. The hypostome and tentacles had denser neural net in comparison with the gastric region. Electron microscopy revealed muscle processes throughout the hydranth body. Neural processes with specific vesicles and neurotubules in their cytoplasm were also shown at an ultrastructural level. This work demonstrates the structure of serotonin-positive neural system and smooth muscle layer in C. radiatum hydranths.     

Advanced Cambrian hydroid fossils (Cnidaria: Hydrozoa) extend the medusozoan evolutionary history

Primitive cnidarians are crucial for elucidating the early evolution of metazoan body plans and life histories in the late Neoproterozoic and Palaeozoic. The highest complexity of both evolutionary aspects within cnidarians is found in extant hydrozoans. Many colonial hydrozoans coated with chitinous exoskeletons have the potential to form fossils; however, only a few fossils possibly representing hydroids have been reported, which still require scrutiny. Here, we present an exceptionally well-preserved hydroid found in the Upper Cambrian Fengshan Formation in northern China. It was originally interpreted as a problematic graptolite with an uncertain systematic position. Based on three characteristic morphological traits shared with extant hydroids (with paired hydrothecae, regular hydrocaulus internodes and special intrathecal origin pattern of hydrocladium), we propose this fossil hydroid as a new genus, Palaeodiphasia gen. nov., affiliated with the advanced monophyletic hydrozoan clade Macrocolonia typically showing loss of the medusa stage. More Macrocolonia fossils reviewed here indicate that this life strategy of medusa loss has been achieved already as early as the Middle Devonian. The early stratigraphical appearance of such advanced hydroid contrasts with previous molecular hypotheses regarding the timing of medusozoan evolution, and may be indicative for understanding the Ediacaran cnidarian radiation.     

Patterns of hydroid (Cnidaria, Hydrozoa) species richness and distribution in an Arctic glaciated fjord

The consequences of global warming are particularly evident in high polar areas. Deglaciation phenomenon—negative mass balance of Svalbard glaciers and recession of tidal glaciers—results in landscape and shoreline change. These areas of very dynamic conditions are now open for primary colonists, among them hydroids, typical early colonists of the vacant substratum. This study aims to explore the patterns of Hydrozoan diversity and distribution in Hornsund (west Spitsbergen). Hydroids associated with shallow water kelp beds as well as those occurring on deeper subtidal soft bottom were collected at sites located along gradients of glacial disturbance (i.e., high mineral sedimentation, ice-berg scouring). Samples were collected by scuba diving (three sites of different distance to active tidal glaciers), van Veen grabs (two sites located in the inner and outer fjord basin), and dredges taken from along a fjord transect. Hydroid diversity differed significantly between sites located in the vicinity of glaciers fronts in glaciated bays and sites comparatively free from glacier disturbance. Glacial disturbance results in low frequencies of occurrence and high levels of rarity of hydroids at sites located close to glacier fronts. The species richness of hydroids colonizing the hard substrate elements present in deeper subtidal decreases along the fjord axis (i.e., along the glacial sedimentation gradient).     

Reproduction of the colonial hydroid Obelia geniculata (L., 1758) (Cnidaria,Hydrozoa) in the White Sea

Populations of the colonial hydroid Obelia geniculata in the White Sea reproduce asexually by frustule formation. Young medusae appear in the plankton during July and August. The number of medusae rarely exceeds 36 per m³, and the average number varies every year from 0.4 to 10 per m³. The size of medusae is smaller than reported from other regions. The umbrella of the largest recorded medusa was only 0.57 mm in diameter and the specimen had just 35 tentacles. Only a few mature medusae were found during the study. The colonies in the White Sea are epiphytic and grow only on laminarian thalli. At the beginning of July there are no colonies on thalli from the upper subtidal zone. By the end of August, colonies of O.␣geniculata had increased in density to 30 per m². Hydroid recruitment was attributed to active frustule production by colonies living below that zone. The frustules detach from the stems of the hydroids and are found in plankton. Production of frustules on branches occurs continuously during colony growth until water temperatures climb above 0 °C. We found that water temperature in this Arctic environment is generally too low for medusa maturation and planula development in the species. Propagation by frustule formation is the principal means of reproduction in Obelia geniculata within the White Sea, and this phenomenon accounts for the species being a dominant epiphyte on laminarian thalli there.     

Spectral diversity among the members of the family of Green Fluorescent Protein in hydroid jellyfish (Cnidaria, Hydrozoa)

The cDNAs encoding the genes of new proteins homologous to the well-known Green Fluorescent Protein (GFP) from the hydroid jellyfish Aequorea victoria were cloned. Two green fluorescent proteins from one un-identified anthojellyfish, a yellow fluorescent protein from Phialidium sp., and a nonfluorescent chromoprotein from another unidentified anthojellyfish were characterized. Thus, a broad diversity of GFP-like proteins among the organisms of the class Hydrozoa in both spectral properties and primary structure was shown.     

Benthic hydroids (Cnidaria,Hydrozoa) from the Balleny Islands (Antarctica)

Twenty-two species of benthic hydroids, belonging to ten families and 14 genera, were found in a hydroid collection obtained in the Balleny Islands during the BioRoss expedition with the NIWA research vessel Tangaroa in 2004. Twenty of those species constitute new records for the Balleny Islands, raising the total number of known species in the area to 25. Most are members of the subclass Leptothecata, although the subclass Anthoathecata is also relatively well represented. Kirchenpaueriidae and Sertulariidae constitute families with the greatest numbers of species in the collection, with five species (20%) each. Oswaldella with five species (20%) and Staurotheca with four (16%), were the most diverse genera. Twelve species (63%) are endemic to Antarctic waters, most of them with a circum-Antarctic distribution, and 17 (89%) are restricted to Antarctic or Antarctic/sub-Antarctic waters. Although the Balleny Islands hydroid fauna seems to be a typical Antarctic assemblage, it has some striking peculiarities, namely the absence or low representation of some typical and widespread Antarctic genera (Antarctoscyphus and Schizotricha/Symplectoscyphus, respectively).     

DNA barcoding reveals cryptic diversity in marine hydroids (Cnidaria, Hydrozoa) from coastal and deep-sea environments

Fifty-six sequences of the mitochondrial 16S RNA gene were generated for hydroids, belonging to six nominal families — Eudendriidae, Lafoeidae, Haleciidae, Sertulariidae, Plumulariidae and Aglaopheniidae — collected from bathyal environments of the Gulf of Cadiz (22 haplotypes), Greenland (1 haplotype), Azores (1 haplotype), the shallow waters of the UK (17 haplotypes) and Portugal (2 haplotypes). When combined and analysed with 68 additional sequences published in GenBank, corresponding to 63 nominal species of these families (nine species in common between the GenBank sequences and those presented by the authors), cryptic species were detected (e.g. two species of Nemertesia and other of Lafoea ), as well as apparent cases of conspecificity (e.g. Nemertesia antennina and N. perrieri and Aglaophenia octodonta , A. pluma and A. tubiformis ). Other taxonomic inconsistencies were found in the data including cases where species from different genera clustered together (e.g. Sertularia cupressina , Thuiaria thuja , Abietinaria abietina and Ab. filicula ). The mitochondrial 16S rRNA proved to be a useful DNA 'barcode' gene for hydroids, not only allowing discrimination of species, but also in some cases of populations, genera and families, and their intra- or interphylogenetic associations. Although still under-represented in public data bases, the 16S rRNA gene is starting to be used frequently in the study of hydroids. These data provide powerful complementary evidence for advancing our understanding of hydrozoan systematics.     

Benthic hydroids (Cnidaria, Hydrozoa) from off Bouvet Island (Antarctic Ocean)

Twenty-seven species of benthic hydroids have been found in a small collection from off Bouvet Island (Antarctic Ocean). The material was obtained during the XXI/2 German Antarctic expedition with R.V. Polarstern 2003–2004. Of the 27 species collected, 21 were unknown from those waters. Consequently, the number of known species of benthic hydroids from the area has risen to 32, representing a high diversity location for this group in the Southern Ocean considering the sampling effort made. All species, including those previously known from Bouvet waters, are considered with respect to geographical distribution.The present work is an addition to the special issue “Macrobenthic studies at Bouvet island”, presenting work carried out from on board RV Polarstern in 2003/2004 and published in Polar Biology 29 (2006)     

Samuraia tabularasa gen. nov., sp. nov. (Cnidaria,Hydrozoa, Hydrocorynidae), an intertidal hydroid from the Gulf of California,Mexico

Samuraia tabularasa, the samurai hydroid, a previously unreported genus and species of athecate hydrozoan, family Hydrocorynidae, is described, based upon field and laboratory observations. Colonies live attached to rocky substrates in the middle of the intertidal zone in the northern and central Gulf of California, Mexico. The principal characters that allow this species to be referred to a new genus are associated with its mode of sexual reproduction by eumedusoids that can remain attached to the colony, or be released as ephemeral, rudimentary structures. This is in contrast to the feeding, free medusae produced by the two species of the other genus, Hydrocoryne, in the family Hydrocorynidae.     

A new deep-sea hydroid (Cnidaria: Hydrozoa) from the Bering Sea Basin reveals high genetic relevance to Arctic and adjacent shallow-water species

The marine benthic fauna in Arctic shallow-water is reported to be a relatively young assemblage by species of either Pacific or Atlantic affinity. Whether current deep-sea Pacific species are included in the affinity or not is unknown. Combining morphological comparisons and genetic analyses, a new deep-sea hydroid to science, Sertularia xuelongi sp. nov. (Cnidaria: Hydrozoa: Sertulariidae), is described from the northern margin of the Bering Sea Basin at depths of 800–1570 m collected in 2010. It is characterized by slender and zigzag-shaped hydrocauli, alternately arranged hydrothecae and the absence of distal-lateral horns in fully matured female gonothecae. Its distribution, currently known only from Bering Sea Basin, suggests that it could not be an Arctic species with Pacific affinity. However, phylogenetic analyses based on the mitochondrial 16S rRNA gene show that it is clustered into a distinctive clade with four closely related species recorded from shallow-water of Northwest France, Iceland, Chukchi Sea and/or Bering Sea. In addition, its sequence similarity is highly relevant to these four species: Sertularia argentea (98.6 %), S. cupressina (98.8 %), S. plumosa (98.8 %) and S. robusta (99.4 %). All these provide a new insight into the relevance of North Pacific deep-sea species to the benthic fauna in Arctic and adjacent shallow-water. The taxonomic restriction of the genus Sertularia and the re-validation of the genus Polyserias are discussed. Future researches on more deep-sea species from Pacific and/or Atlantic are required to understand the evolution and speciation pattern involved in polar relevance.     

A new chondrophorine (Cnidaria,Hydrozoa) from the cadiz formation (Middle Cambrian) of California

We describe a new species of chondrophorine hydrozoan,Palaelophacmaea valentinei sp. nov., from the early Middle Cambrian part of the Cadiz Formation of the Marble Mountains of southeastern California. This find extends the stratigraphic range of this genus into the early Middle Cambrian and its geographic range into the western United States. We review various chondrophorine-like fossils and present a tentative chondrophorine phylogeny in light of this find.     

Four new species of Hydromedusae (Cnidaria, Hydrozoa) from the coast of south-western Africa

Four previously unknown species of hydromedusae are described from plankton samples collected during oceanographic cruises undertaken along the south-western coast of Africa. The Anthomedusa Bythotiara capensis sp.n., known from a single specimen, was found in shallow waters of the Cape region (South Africa). The Leptomedusa Margalefia intermedia gen. et sp.n. collected in Namibian waters, possesses desmoneme cnidocysts. This category of cnidocysts is previously unreported in the Leptomedusae, but is common in Anthomedusae and in the limnomedusan family Proboscidactylidae. Margalefia seems to occupy a position intermediate between the families Tirannidae and Laodiceidae. Two species of Limnomedusae, Aglauropsis edwardsii sp.n. and Proboscidactyla menoni sp.n. were frequent at several stations in Namibian waters between depths of 50 m and the surface.