Hydroid Species Research Articles

Sea Jelly Spectacular – Influence on China's Aquariums

Jellyfish are one of the oldest multi-organ animals found today; dating back at least 500 million years and some say even as many as 700 million years. There are even two or three that are considered immortal in that they can revert back to their polyp stage from the medusa stage. How amazing is that? But their increased prominence in our oceans is due to fishing down the food chain so that sea jellies have fewer predators and to the increased nutrients we are adding to our oceans via the rivers where the fertilizers and other chemical run off our land and into the water. Climate change is also affecting our sea jelly populations. Sea jellies are beautiful, graceful, elegant and mesmerizing and because of that, we have the opportunity to connect our visitors emotionally to our oceans and inspire the care and behaviour changes needed to help our oceans become healthy again.Over the past 500-plus million years, these beautifully tetra-radial symmetrical jellies have diversified with over 200 scyphozoans, and possibly up to a couple of thousand hydrozoan species. They can live for only a few hours to six months in the wild, though in our aquariums, they have lived much longer. They have even diversified how they reproduce from asexual budding and fission to sexual reproduction, which makes our job of maintaining sustainable populations within our facilities all the more challenging, and no wonder these amazing jellies have fascinated us for decades.

Notes on some hydroids (Cnidaria) from Martinique, with descriptions of five new species

The present report supplements a series of earlier accounts on the hydrozoan fauna of the French Lesser Antilles, and discusses 16 species of hydroids from Martinique. Of these, five are new to science: Hydractinia promiscua, Halecium plicatum, Dynamena bimorpha, Antennella quaterna and Monostaechas bertoti. The medusoid gonophores of Ralpharia gorgoniaePetersen, 1990 are described in detail. The female gonothecae of Halecium labiatumBillard, 1933, recorded for the second time, are redescribed. Characters of the trophosome and the cnidome composition allowed a reliable identification of Halecium lightbourniCalder, 1991, a species whose previously unknown gonothecae are here described for the first time. A reexamination of the type of Dynamena tropicaStechow, 1926 proved that it is conspecific with D. crisioides Lamouroux, 1824. Sertularia notabilisFraser, 1947 is included in the synonymy of S. hattoriiLeloup, 1940, and arguments for doing so are provided. The so called variety pusillaRitchie, 1910, associated for a long time with Hincksella cylindrica (Bale, 1888), is raised to species, as H. pusilla (Ritchie, 1910), and their distinguishing characters are emphasized. Clytia edentula Gibbons & Ryland, 1991 is found for the second time, extending its known range of distribution.

On some hydroids (Cnidaria, Hydrozoa) from the Okinawa Islands, Japan

This paper gives a systematic account of 32 hydroid species identified in a small collection originating from the Okinawa Islands. While most species are well-known from Japanese waters, three new species and five new records for Japan were found. Some not well known species are redescribed. Taxonomically important features of nearly all species are depicted. The new species are: Schizotricha longinema new spec., Cladocarpus unilateralis new spec., and Macrorynchia crestata new spec. Zygophylax pacifica Stechow, 1920 is recognised as a new synonym of Zygophylax cyathifera (Allman, 1888). New records for Japanese waters are: Lytocarpia delicatula, Macrorhynchia fulva, Caminothujaria molukkana, Zygophylax rufa, Thyroscyphus fruticosus. The presence of Zygophylax cervicornis and Aglaophenia cupressina in Japanese waters are confirmed by new, fertile material.

George James Allman (1812-1898): pioneer in research on Cnidaria and freshwater Bryozoa.

George James Allman (1812-1898), acclaimed for pioneering studies of Hydrozoa and Bryozoa, was born in Cork, Ireland. He earned B.A. (1839) and M.B. (1843) degrees at Trinity College, Dublin, and an M.D. (1847) from Trinity College and Oxford University. Choosing academia over medicine, he served as Professor of Botany, University of Dublin (1844-1855), and as Regius Professor of Natural History, University of Edinburgh (1855-1870). Allman initially undertook research on freshwater bryozoans, but his interests later turned to marine hydroids. His bibliography, with publication dates retraced herein, comprises more than 200 titles. Most important of these were monographs on limnic Bryozoa (1857) and "gymnoblastic" or anthoathecate Hydrozoa (1871, 1872). Other prime works were on hydroids from the Straits of Florida (1877) and from the Challenger Expedition (1883, 1888). He named 22 families, 64 genera and 283 species of Hydrozoa, along with three families and nine species of Bryozoa. Of these, names of some five families, 19 genera, and 146 species of hydrozoans, along with three families and three species of bryozoans, are currently recognized as valid. For distinguished academic service, Allman was awarded the Royal Medal (Royal Society of London, 1873), the Brisbane Prize (Royal Society of Edinburgh, 1873), the Cunningham Medal (Royal Irish Academy, 1878), the Gold Medal (Linnean Society of London, 1896), and an LL.D. from the University of Edinburgh (1873). He died 24 November 1898 in Parkstone, Dorset, England. Two genera and 22 species have been named in his honour.

Serpulidae (Annelida) of Lizard Island, Great Barrier Reef, Australia.

Serpulidae are obligatory sedentary polychaetes inhabiting calcareous tubes that are most common in subtropical and tropical areas of the world. This paper describes serpulid polychaetes collected from Lizard Island, Great Barrier Reef, Australia in 1983-2013 and deposited in Australian museums and overseas. In total, 17 serpulid genera were recorded, but although the study deals with 44 nominal taxa, the exact number of species remains unclear because a number of genera (i.e., Salmacina, Protula, Serpula, Spirobranchus, and Vermiliopsis) need world-wide revisions. Some species described herein are commonly found in the waters around Lizard Island, but had not previously been formally reported. A new species of Hydroides (H. lirs) and two new species of Semivermilia (S. annehoggettae and S. lylevaili) are described. A taxonomic key to all taxa found at Lizard Island is provided.

Two new genera and nine new species of hydroids (Cnidaria: Hydrozoa) from off New Caledonia

Two new genera and nine new species of hydroids are described based on deep-water material collected from off New Caledonia during various expeditions of the French Tropical Deep-Sea Benthos program. Caledoniana gen. nov., provisionally included in the family Sertulariidae Lamouroux, 1812, presently comprises three new species, viz. C. alata sp. nov., C. decussata sp. nov., and C. microgona sp. nov., while an additional group of three new species, is accommodated in the new sertulariid genus Solenoscyphus gen. nov.: S. candelabrum sp. nov., S. decidualis sp. nov., and S. striatus sp. nov. Furthermore, three new species of Hincksella Billard, 1918 (family Syntheciidae Marktanner-Turneretscher, 1890) are described, namely H. cornuta sp. nov., H. neocaledonica sp. nov., and H. similis sp. nov.

A photoactivatable green-fluorescent protein from the phylum Ctenophora.

You have accessMoreSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail Cite this article Haddock Steven H. D., Mastroianni Nadia and Christianson Lynne M. 2015A photoactivatable green-fluorescent protein from the phylum CtenophoraProc. R. Soc. B.2822015105520151055http://doi.org/10.1098/rspb.2015.1055SectionYou have accessRetractionA photoactivatable green-fluorescent protein from the phylum Ctenophora Steven H. D. Haddock Steven H. D. Haddock Google Scholar Find this author on PubMed Search for more papers by this author , Nadia Mastroianni Nadia Mastroianni Google Scholar Find this author on PubMed Search for more papers by this author and Lynne M. Christianson Lynne M. Christianson Google Scholar Find this author on PubMed Search for more papers by this author Steven H. D. Haddock Steven H. D. Haddock Google Scholar Find this author on PubMed Search for more papers by this author , Nadia Mastroianni Nadia Mastroianni Google Scholar Find this author on PubMed Search for more papers by this author and Lynne M. Christianson Lynne M. Christianson Google Scholar Find this author on PubMed Search for more papers by this author Published:07 August 2015https://doi.org/10.1098/rspb.2015.1055This article retracts the followingResearch ArticleA photoactivatable green-fluorescent protein from the phylum Ctenophorahttps://doi.org/10.1098/rspb.2009.1774 Steven H. D. Haddock, Nadia Mastroianni and Lynne M. Christianson volume 277issue 1685Proceedings of the Royal Society B: Biological Sciences16 December 2009In the years following the publication of ‘A photoactivatable green-fluorescent protein from the phylum Ctenophora’ [1], another research group [2] sequenced hydrozoan (Cnidaria) fluorescent proteins that were very similar to those we cloned from cDNA prepared from ctenophore specimens. We therefore now believe that the green-fluorescent proteins reported in our study are not from ctenophores, and were due to incorporation of cnidarian prey into the ctenophore tissues.Although our genes were cloned from two independent samples of mRNA taken years apart, the similarity of our sequences to those obtained from a siphonophore (Cnidaria, Hydrozoa) indicate that this mRNA was carried over from ingested material. This ctenophore species is known to prey on cnidarians, but we did not expect that mRNA would persist for as long as it did, and we regret our erroneous conclusion.What is remarkable about this situation is that the ctenophore, in addition to maintaining full-length mRNA for the fluorescent protein, also incorporated the proteins into its tissue to the extent that its bioluminescence emission was green-shifted. While the exact species of origin for these proteins is unknown, the photoactivatable properties of this fluorescent protein are as originally described, and it remains an interesting target for future research and application.Steven H. D. HaddockMonterey Bay Aquarium Research Institute, 7700 Sandholdt Road,Moss Landing, CA 95039, USAe-mail: [email protected]Nadia MastroianniAxxam SpA, San Raffaele, Biomedical Science Park, via Olgettina 58,20132 Milan, Italye-mail: [email protected]Lynne M. ChristiansonMonterey Bay Aquarium Research Institute, 7700 Sandholdt Road,Moss Landing, CA 95039, USAe-mail: [email protected]Footnotes© 2015 The Author(s)Published by the Royal Society. All rights reserved.References1Haddock SHD, Mastroianni N, Christianson LM. 2010A photoactivatable green-fluorescent protein from the phylum Ctenophora. Proc. R. Soc. B 277, 1155–1160. (doi:10.1098/rspb.2009.1774) Link, ISI, Google Scholar2Hunt ME, Modi CK, Aglyamova GV, Ravikant DVS, Meyer E, Matz MV. 2015Multi-domain GFP-like proteins from two species of marine hydrozoans. Photochem. Photobiol. Soc. 11, 637–644. (doi:10.1039/c1pp05238a) Crossref, ISI, Google Scholar Previous Article VIEW FULL TEXT DOWNLOAD PDF FiguresRelatedReferencesDetailsRelated articlesA photoactivatable green-fluorescent protein from the phylum Ctenophora16 December 2009Proceedings of the Royal Society B: Biological Sciences This Issue07 August 2015Volume 282Issue 1812 Article InformationDOI:https://doi.org/10.1098/rspb.2015.1055PubMed:26224709Published by:Royal SocietyOnline ISSN:1471-2954History: Published online07/08/2015Published in print07/08/2015 License:© 2015 The Author(s)Published by the Royal Society. All rights reserved. Citations and impact Subjectsbiochemistry Large datasets are available through Proceedings B's partnership with Dryad

Interspecific Differential Expression Analysis of RNA-Seq Data Yields Insight into Life Cycle Variation in Hydractiniid Hydrozoans.

Hydrozoans are known for their complex life cycles, which can alternate between an asexually reproducing polyp stage and a sexually reproducing medusa stage. Most hydrozoan species, however, lack a free-living medusa stage and instead display a developmentally truncated form, called a medusoid or sporosac, which generally remains attached to the polyp. Although evolutionary transitions in medusa truncation and loss have been investigated phylogenetically, little is known about the genes involved in the development and loss of this life cycle stage. Here, we present a new workflow for evaluating differential expression (DE) between two species using short read Illumina RNA-seq data. Through interspecific DE analyses between two hydractiniid hydrozoans, Hydractinia symbiolongicarpus and Podocoryna carnea, we identified genes potentially involved in the developmental, functional, and morphological differences between the fully developed medusa of P. carnea and reduced sporosac of H. symbiolongicarpus. A total of 10,909 putative orthologs of H. symbiolongicarpus and P. carnea were identified from de novo assemblies of short read Illumina data. DE analysis revealed 938 of these are differentially expressed between P. carnea developing and adult medusa, when compared with H. symbiolongicarpus sporosacs, the majority of which have not been previously characterized in cnidarians. In addition, several genes with no corresponding ortholog in H. symbiolongicarpus were expressed in developing medusa of P. carnea. Results presented here show interspecific DE analyses of RNA-seq data to be a sensitive and reliable method for identifying genes and gene pathways potentially involved in morphological and life cycle differences between species.

Biogeography of jellyfish in the North Atlantic, by traditional and genomic methods

Abstract. Scientific debate on whether or not the recent increase in reports of jellyfish outbreaks represents a true rise in their abundance has outlined a lack of reliable records of Cnidaria and Ctenophora. Here we describe different jellyfish data sets produced within the EU programme EURO-BASIN. These data were assembled with the aim of creating an improved baseline and providing new data that can be used to evaluate the current diversity and standing stocks of jellyfish in the North Atlantic region. Using a net adapted to sample gelatinous zooplankton quantitatively, cnidarians and ctenophores were collected from the epipelagic layer during spring–summer 2010–2013, in inshore and offshore waters between lat 59 and 68° N and long 62° W and 5° E. Jellyfish were also identified and counted in samples opportunistically collected by other sampling equipment in the same region and at two coastal stations in the Bay of Biscay and in the Gulf of Cádiz. Continuous Plankton Recorder (CPR) samples collected in 2009–2012 were re-analysed with the aim of identifying the time and location of cnidarian blooms across the North Atlantic Basin. Overall the data show high variability in jellyfish abundance and diversity, mainly in relation to different water masses and bathymetry. Higher densities were generally recorded on the shelves, where the communities tend to be more diverse due to the presence of meropelagic medusae. Comparison of net records from the G.O. Sars transatlantic cruise shows that information on jellyfish diversity differs significantly depending on the sampling gear utilised. Indeed, the big trawls mostly collect relatively large scyphozoan and hydrozoan species, while small hydrozoans and early stages of Ctenophora are only caught by smaller nets. Based on CPR data from 2009 to 2012, blooms of cnidarians occurred in all seasons across the whole North Atlantic Basin. Molecular analysis revealed that, contrary to previous hypotheses, the CPR is able to detect blooms of meroplanktonic and holoplanktonic hydrozoans and scyphozoans. Through combination of different types of data, key jellyfish taxa for the spring–summer period were identified in the northern North Atlantic regions. Key species for the central and southern North Atlantic could be inferred based on the blooms identified by the CPR survey, although this should be confirmed further by comparison with quantitative data. The identification by DNA barcoding of 23 jellyfish specimens collected during the EURO-BASIN cruises contributes to increasing the still very limited number of jellyfish sequences available on GenBank. All observations presented here can be downloaded from PANGAEA (http://doi.pangaea.de/10.1594/PANGAEA.835732).

A unified assessment of marine Mediterranean assemblages: a lesson from benthic hydroids

Hydroids are important components of the communities of rocky bottom shallow coastal areas. The hydrozoan fauna of the Mediterranean Sea is probably one of most investigated in the world, with lots of faunistic and biogeographical studies. However, quantitative studies using the same sampling methodology and controlled sampling effort have been restricted to areas in the Western and Central Mediterranean. We compared hydroid assemblages in four areas of the Mediterranean Sea, from the Gulf of Cádiz to the South Adriatic Sea, following the same sampling and quantification methodology. Our analysis showed the dominant Atlantic character of the assemblages of the Gulf of Cádiz and the South Alboran Sea because of the influence of the inflowing Atlantic waters. Conversely, the hydroid assemblages of the North Alboran Sea were more similar to the assemblages in the Ligurian and in the South Adriatic, and with a number of species ranking between the observed in these two Mediterranean zones. Fourteen species were identified as making the most significant contributions to characterizing the Mediterranean hydroid species pool from a quantitative point of view. These taxa include species previously named as typical components of the Mediterranean hydroid fauna as well as those only recently recorded in the region (Eudendrium moulouyensis) and invaders such as Clytia hummelincki.

Review of some little-known benthic hydroids (Cnidaria, Hydrozoa) from the Southern Ocean.

A number of benthic hydroid species inhabiting the Southern Ocean are insufficiently characterized. A revision of eight little-known Antarctic species of the order Anthoathecata was made, based on the study of type material. Some of the species have not been recorded since their original description a century ago. Four species (Bimeria corynopsis, Bougainvillia macloviana, ?Koellikerina belgicae and Rhizorhagium antarcticum) belong to the family Bougainvilliidae, two species (Hydractinia angusta and H. dendritica) to the family Hydractiniidae, Perarella clavata to the family Cytaeididae and, finally, Rhysia halecii to the family Rhysiidae. For each species a list of synonyms, a description, a discussion on its relationship with other species and its systematic position, and an account of its autecological data are given. All records found in the literature have been checked.

The hydrozoan fauna (Cnidaria: Hydrozoa) from the peaks of the Ormonde and Gettysburg seamounts (Gorringe Bank, NE Atlantic).

Twenty-seven species of hydroids were collected from the peaks (35-42 meters depth) of the Gorringe Bank (NE Atlantic) during the oceanographic campaign 'LusoExpedição Olympus 2008'. Twenty-one of these species are new for the Gorringe Bank that now has published records for a total of 37 hydroid species. Lafoeina tenuis, Sertularella ellisii and Clytia hemisphaerica were the most abundant hydroid species collected. Results revealed spatial differences in the composition of species assemblages along the summits of the Gorringe, as only 14 of the species sampled were found both in the Ormonde and Gettysburg seamounts. The large density of algae at the peaks of the seamounts sustain a considerable hydrozoan diversity (23 species), but visibly inhibits the establishment of hydroids to the rocky substrates (only 2 species found). All the known hydrozoan species from the peaks of the Gorringe were exclusively collected during summer, thus sampling in other seasons may reveal further hydrozoan diversity due to seasonal patterns of growth of algae and hydroids. Nevertheless, the reasonably high levels of hydrozoan biodiversity demonstrated only from a small portion the summits of the Gorringe, corroborate its seamounts as 'biodiversity hotspots'. In agreement with previous investigations with shallow-water molluscs and sponges, the shallow-water hydroid fauna of the Gorringe revealed greater biogeographical affinities with the Mediterranean and mainland Portugal. This is the first report of Eudendrium armatum outside of the Mediterranean.

New records of jellyfish species in the Marmara Sea

This manuscript reports the first observations of three species of Hydrozoa (Podocorynoides minima, Koellikerina fasciculata and Gastroblasta raffaelei) and one species of Scyphozoa (Discomedusa lobata) in the Marmara Sea that were sampled in 2006–2011. Their possible introduction pathways, some ecological and distributional details are briefly discussed here.

Hydroid gardens of Nemertesia ramosa (Lamarck, 1816) in the central North Atlantic

Nemertesia ramosa (Lamarck, 1816) is a large eurybathic hydrozoan species. Its habitat and spatial distribution in the Azores archipelago (central North Atlantic) are described based on 22 new records collected in situ by scuba diving and by observations using a drop-down camera and remote operated vehicles (ROVs) between 2004 and 2011. N. ramosa grows on hard substrates in mono and multi-specific assemblages. In the Azores it is well known in the sublittoral at 15–158 m depth in the central group of islands, but historical records exist from seamounts down to bathyal grounds of nearly 1000 m. Scuba diving surveys generally reveal N. ramosa as an occasionally occurring and rare species in the infralittoral (1–9 colonies 10−3 m−2), although it may also be common and even abundant at some sites. A circalittoral aggregation was assessed in detail exhibiting densities of up to 2.82 colonies m−2 on rocky substrate and one order of magnitude lower on mixed bottom (0.25–0.55 colonies m−2). An aggregated spatial distribution is described, with aggregations being considered hydroid gardens (>1–9 10−1 m−2). Colonies measured on ROV imagery averaged 23.5 cm in height (STD = 4.1). Taller colonies (max = 36.7 cm) were registered on rocky outcrops protruding more than 15 cm. N. ramosa co-occurred mainly with brown and red algae, bryozoans, polychaetes, and other hydroids. A diverse ichthyofauna was associated to these habitats. Circalittoral communities of N. ramosa included hydrozoans, sponges, and fish.

Hydroids of the genus Sertularella (Cnidaria: Hydrozoa: Sertulariidae)from the Pacific coast of Canada in the collection of the Royal Ontario Museum, with descriptions of four new species.

Examination of the hydroid fauna of the Canadian Pacific coast in the collections of the Royal Ontario Museum collected between 1934 and 1985 indicates that the genus Sertularella Gray, 1848 from the infralittoral zone in the region remains poorly enumerated. The present study shows that several European or northeast Atlantic hydroid species, Sertularella conica Allman, 1877, Sertularella rugosa (Linnaeus, 1758), Sertularella tenella Alder, 1856, Sertularella polyzonias (Linnaeus, 1758), and Sertularella fusiformis (Hincks, 1861) have been incorrectly reported from the west coast of North America and suggests that assumptions of cosmopolitanism of some species require verification by continuing refinement of regional species-level taxonomy. Four new species, Sertularella cervicula, S. coronata, S. sacciformis, and S. pacifica are recognized and described in this paper. Sertularella gigantea Hincks, 1874 is recognized for the first time from the Pacific coast of North America.

On the benthic hydroids from the Scotia Arc (Southern Ocean): new insights into their biodiversity, ecology and biogeography

The Scotia Arc, located between the Antarctic Peninsula and the southern tip of South America, is an important zone from the biogeographic point of view. Its benthic biodiversity has been extensively documented with a few exceptions, among others, the hydroid fauna, which constitutes one of the major components of the benthic Antarctic communities. With the aim of increasing the data in three different but complementary fields of knowledge (namely biodiversity, ecology and biogeography), an unpublished collection obtained during the German Antarctic expedition ANTARKTIS XIX/5 (LAMPOS) with the RV Polarstern in 2002 has been studied. A total of 45 species of benthic hydroids, belonging to 9 families and 20 genera, was found. Forty of them, including Halecium stoloniferum sp. nov. and Schizotricha discovery sp. nov., were identified to the species level. Leptothecata was by far the most dominant order with 42 species, while Anthoathecata was only represented by 3 species. Fifteen species (38 %) are endemic to the Antarctic region and 31 (78 %) restricted to Antarctic and/or sub-Antarctic waters. Schizotricha southgeorgiae, Halecium elegantulum and Sertularella argentinica are reported for the second time, whereas Schizotricha jaederholmi, Antarctoscyphus gruzovi and Sertularella jorgensis for the third time. New original autoecological data concerning the use of the substrate, reproductive phenology and bathymetric range of the inventoried species are provided.

The non-Siphonophoran Hydrozoa (Cnidaria) of Salento, Italy with notes on their life-cycles: an illustrated guide.

The majority of Hydrozoa is represented by not readily noticeable, small species. In recent decades, however, taxonomic knowledge of the group has increased worldwide, with a significant number of investigations focused on the Mediterranean Sea. Over more than two decades, 115 species of hydrozoans were recorded from coastal waters along nearly 300 km of the Salento Peninsula (Apulia, Italy). For each species, records from different collections were merged into single sheets of a general database. For each species, the following information is reported: description, cnidome, biology, occurrence in Salento, worldwide distribution, and bibliography. Descriptions refer to the benthic hydroid stage and, when present, also to the planktonic medusa stage. The 115 species of Hydrozoa, recorded along the Salento coastline, represent 25% of the Mediterranean Hydrozoa fauna (totaling 461 species), and nearly 3% of 3,702 world's known species covered in a recent monograph. Four species are non-indigenous, three of them with invasive behavior (Clytia hummelincki, Clytia linearis, and Eudendrium carneum), and one species now very common (Eudendrium merulum) in Salento. The complete life cycle of Clytia paulensis (Vanhöffen, 1910) is described for the first time.

Similiclava nivea (Cnidaria: Hydrozoa: Similiclavidae): a new family, genus and species of athecate hydroid from the Pacific coast of North America

The hydroid Similiclava nivea, gen. nov., sp. nov., is described from colonies collected in nearshore waters of southern British Columbia, Canada. It has been observed by divers, and recorded as Clava sp., several hundred times at locations between southeast Alaska and southern Oregon, USA. While resembling the hydractiniid Clava multicornis, tentacles of S. nivea are arranged in two close whorls in extended hydranths rather than being scattered over the distal end of the hydranth. Moreover, the hypostome is dome-shaped to flattened instead of being proboscidiform. Similiclava nivea also resembles species of the hydractiniid genera Stylactaria, Hydractinia and Podocoryna, but differs in being monomorphic, in lacking spines on the hydrorhiza and in having numerous (as many as 50 or more) sporosacs borne in a broad whorl below the tentacles on normal hydranths. Molecular analysis using the mitochondrial 16S gene sequences reveals that S. nivea is closer to Clathrozoellidae than to Hydractiniidae, although it is clearly distinct from both. A new family, Similiclavidae, is established to accommodate the species. Hydroids of S. nivea were observed at relatively shallow depths (10–30 m) on rocks and epibiota attached to rocky substrates. Colonies are conspicuous because of the relatively large surface area they occupy (up to 20 cm across, and in aggregations often exceeding 100 or more hydranths) together with the height (about 15 mm high when extended) and striking white colour of living hydranths. The cnidome consists of desmonemes, microbasic euryteles and microbasic mastigophores. A substrate generalist observed on rocks, algae, sponges, barnacles, bryozoans and other hydroids in cold-temperate waters, S. nivea is most prevalent in shallow subtidal areas swept by tidal currents.http://zoobank.org/urn:lsid:zoobank.org:pub:2691E02E-7E14-4820-8D91-41D9E7E8BF62

The nerve ring in cnidarians: its presence and structure in hydrozoan medusae

In our previous studies of the Hydra nerve ring, we proposed the following hypothesis: “The nerve ring in the hypostome of Hydra is a central nervous system (CNS)-like neuronal structure.” Related to this hypothesis, we have started to survey the nerve ring immunocytochemically using antibodies against neuropeptides throughout the whole phylum of cnidarians. In the present study, we describe nerve rings in hydrozoan medusae. We examined the medusae of five hydrozoan species belonging to three orders: Eirene sp. (order Leptomedusae), Craspedacusta sowerbyi (order Limnomedusae), Sarsia tubulosa, Turritopsis nutricula, and Cladonema radiatum (order Anthomedusae). We observed a well-developed nerve ring in all species. The nerve ring runs circumferentially around the margin of the bell. In all cases, the nerve ring was visualized by plural antibodies, suggesting that it contains different neural subpopulations. In C. radiatum, antibodies against four different neuropeptides labeled the nerve ring. We established clear (without undesirable cross-reactions) double-staining procedures with two rabbit primary antibodies. Using the double-staining method, three neural subsets visualized by three antibodies revealed completely separate neural populations. The results show that the nerve ring is a common feature in hydrozoan medusae and has a complex heterogeneous structure composed of different neural subsets.

Feeding preferences of lumpfish (Cyclopterus lumpus L.) maintained in open net-pens with Atlantic salmon (Salmo salar L.)

Abstract Feeding preferences of juvenile lumpfish reared together with Atlantic salmon in sea pens were assessed. Juvenile lumpfish, initial mean (± SE) weight of 54.0 ± 0.9 g, were reared in small sea cages (125 m3, 5 × 5 × 5 m) together with Atlantic salmon with an initial mean (± SE) weight of 619 ± 2.5 g. Lumpfish were stocked at 10 and 15% density (12 and 18 lumpfish vs. 120 salmon, respectively) in replicate sea pens. To determine the feeding preferences of lumpfish in the cages gastric lavage was performed every two weeks and the feeding items were identified and categorized as: a) consumed sea lice, b) formulated feed fragments, c) crustacean species, d) hydrozoan species, e) Mytilus edulis, f) unidentified material or no contents found. The most common food item identified in the stomachs of lumpfish throughout the study period was fragments of salmon pellets. Results indicate that lumpfish in sea pens can be classified as strongly opportunistic and the fish do not restrict themselves or rely on a single food source if others are present. Lumpfish seemed to switch their preference towards which ever food item that was most readily available to them within their environment. The present data shows temporal changes in feed choice throughout the period, seemingly linked to food availability.