bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of the Adhesion of the Podia in the Asteroid Asterias Rubens (Echinodermata)
Authors: Flammang Patrick , Walker Graham 
Published: May 2009

The adhesion of single podia of Asterias rubens (Echinodermata) was tested under different conditions in order to determine those factors which have an effect on the adhesive forces. In common with many other marine organisms, the adhesion of the podia is sensitive to surface properties of the substratum. The effect of immersion and emersion on tenacity (force per unit area) has been tested. Working with the asteroids completely immersed in sea-water appears to be the best technique to measure the adhesive forces of the podia. The mean tenacity of the podia of A. rubens on glass underwater is 1·98×105 Nm−2.The measurement of the adhesion strength of marine invertebrates and of its variation under different conditions may give clues to how marine bioadhesives function. Adhesive forces have usually been measured in invertebrates using either permanent or transitory adhesion, but only rarely recorded in animals using temporary adhesion (for review see Walker, 1987).Of all macrobenthic organisms, echinoderms have exploited temporary adhesion most efficiently. In echinoderms, adhesive systems are usually associated with the podia and are involved in locomotion, attachment, feeding, or burrowing (Flammang, 1996). The paucity of information regarding the adhesive strength of echinoderm podia is due possibly to the fact that these animals possess a multitude of podia that are not all attached at the same time, making it difficult to evaluate the exact number of podia involved in adhesion at any precise instant in time. For example, maximum detachment forces involving many podia have been measured for several asteroid species. Feder (1955) measured up to 4 kg (39·64 N) in Pisaster ochraceus, Lavoie (1956) over 3 kg (29·43 N) in Asterias forbesi, and Christensen (1957) 5 kg (49·05 N) in Evasterias troscheli. Unfortunately, the number of podia adhering to the substratum was not estimated in any of these studies. It is not possible, therefore, to calculate tenacity (adhesive force per unit of surface area) which makes comparisons impossible either between these different asteroids or with other marine invertebrates (see Walker, 1987). Tenacity has been considered in only one study (Paine, 1926) where the mean adhesive force using single podia of the asteroid A. vulgaris was 17·2 g (0·17 N), giving, when divided by a mean measurement of the surface area of the podial discs, a tenacity of 1·25×105 N m2.
Structure of the Adhesive Surface of the Digital Tentacles ofNautilus Pompilius
Authors: Muntz W. R. A. , Wentworth S. L. 
Published: May 2009

The cirri of the digital tentacles ofNautilus pompiliusare covered by annular ridges, more pronounced on the oral (adhesive) than the aboral side. On the oral side the epithelium is thicker on the proximal and outer surfaces of the ridges than on their distal surfaces. Prominent electron-dense granules occur in the cells of the thick epithelium, but are absent from the thin epithelium and the epithelium of the aboral surface. These granules contain mucopolysaccharide and may be responsible for adhesion.The digital tentacles ofNautilusare used for attachment to, for example, prey, the substratum, or the partner's shell during mating. Their general structure and histology have been described by Owen (1832), Willey (1898), Barber & Wright (1969), Fukuda (1987) and Kier (1987). The mechanism of adhesion is still uncertain. Barber & Wright (1969) report epithelial cells of two types: pigmented cells containing pigment granules 0–5–1 µm in diameter, interspersed with a small number of mucus-producing cells which may help with the adhesive process.
Dry Weights, Carbon and Nitrogen Content of Decapod Larvae from the Plankton
Authors: Lindley J.A. 
Published: May 2009

The carapace lengths, dry weights, carbon content and nitrogen content of decapod larvae sorted from fresh plankton samples were measured. Regressions for the relationships between dry weight and carapace length were determined for each infraorder and for lower taxa. Regressions between carbon content, nitrogen content and C:N ratio and dry weight were calculated for the different taxa and were compared with published data on larvae reared in the laboratory.Decapod larvae often comprise a significant component of the zooplankton of estuaries and inshore waters (Lindley et al., 1994). Lindley (1988) has presented data on the relationship between dry weight and carapace length for brachyuran larvae from the plankton. Similar data for other groups of decapods and additional data and analyses for brachyurans are presented here with data on carbon and nitrogen content. Anger & Harms (1990) described the relationships between dry weight; carbon and nitrogen content for decapod larvae reared under controlled conditions in the laboratory. The results of measurements on specimens caught in the plankton in naturally varying conditions provide a comparison with laboratory reared larvae. Harms et al. (1994) compared dry weights and biochemical data for Carcinus maenas (Brachyura) larvae reared in the laboratory with specimens from the plankton off Helgoland. Dry weights of the last two zoea stages and the megalopa larvae from the plankton were higher. The percentage carbon, nitrogen and lipid content were higher in laboratory raised larvae which were fed on Artemia nauplii than in field specimens or in laboratory reared specimens fed on phytoplankton or starved.
The larval and post-larval hinge of some families of bivalve molluscs
Authors: Le Pennec Marcel 
Published: May 2009

Bivalve larvae constitute an important part of the plankton and there is a pressing need to be able to identify the various species.The study of the development of the larval and post-larval hinge by scanning electron microscopy of 18 bivalve species shows the importance of this structure, which represents the principal character in identification of the young larval stages. This paper presents the principal distinguishing characters of the hinge (denticles, teeth and ligament) in eight families of bivalves.
On the nutrition and metabolism of zooplankton. VIII. the grazing of Biddulphia cells by Calanus helgolandicus
Authors: Corner E. D. S. , Head R. N. , Kilvington C. C. 
Published: May 2009

The rations removed by adult and stage V Calanus helgolandicus (Claus) feeding on large cells of the diatom Biddulphia sinensis Grev. were measured using an apparatus especially designed to keep the plant cells in suspension and estimated to reach a maximum of 1800 cells/animal/day at a food concentrationof 11,300 cells/1. A continual flow method was used to study feeding at very low algal concentrations and it was found that the animals still captured Biddulphia at a food level of only 270 cells/1.The animals in the feeding experiments were used at a very low population density (6 copepods/1350 ml.) and the maximum value found for the volume of sea water swept clear – 700 ml./animal/day - was unusually high.The maximum daily rations consumed by each animal were also high, being equivalent to 47–5 % of the body nitrogen and 46–4 % of the body phosphorus. The number of faecal pellets released by the animals increased with the size of ration captured, but the percentage of the ration lost as faecal pellets was fairly constant. In terms of dietary nitrogen the average value was 65–9% and that for dietary phosphorus 59·6%.The percentage of the daily ration of nitrogen excreted in soluble form was 266% and that of phosphorus 41–2%, these values being significantly higher than those found using unfed animals. Nearly 90 % of the nitrogen excreted by the animals, whether feeding or unfed, was in the form of ammonia. The amounts of excreted ammonia and total soluble phosphorus increased significantly when the animals fed; but the small quantities of nitrogen released in forms other than ammonia did not change.
Volume changes shown by some littoral anomuran crustacea
Authors: Davenport John 
Published: May 2009

P. platycheleswas proved to be an osmoconformer, as expected. It is assumed that the other three species are conformers.Littoral specimens ofE. bernhardushave a similar salinity tolerance toP. platycheles,surviving from between 17 and 20·4‰ salinity to between 40·8 and 51‰ salinity if a median lethal time of above 500 h is taken to indicate survival.The stenohaline speciesG. squamiferaandP. longicornisswell rapidly and die in 60‰ s.w. (20·4‰ salinity). Their locomotion is rapidly impaired by swelling and the integument distorted.P. platycheles,a moderately euryhaline species, is capable of resisting swelling in 60‰ s.w., and eventually regains its original weight.LittoralE. bernhardusshowed an unusual pattern of volume change in 60‰ xs.w. Initial swelling of 15·4‰ in the first hour was great compared with decapods likeC. maenasorP. platycheles,yet did not cause much interference with movement, and was substantially reversed in a few hours.Increased urine production prevents swelling inP. platycheles.It is thought that increased antennary artery pressure and or a shift to a diuretic hormone balance cause increased nitration by the antennal gland.Increased urine production is delayed until substantial swelling has occurred inE. bernhardus.The abdomen ofE. bernhardusmakes up significantly more of the total animal weight in dilute media than in full sea water, confirming the idea that the abdomen is a ‘swelling reservoir’ protecting the rest of the animal from the mechanical effects of water inflow.Salt loss in the urine is more important than integumental loss in both E. bernhardus and P. platycheles when they are placed in 60 % s.w.
Seasonal variation in the strength of byssal attachment of the common mussel Mytilus edulis L.
Authors: Price Hilary Ann 
Published: May 2009

A seasonal cycle in byssal attachment strength of Mytilus edulis is described in a population of mussels on the South Wales coast. Attachment strength reaches a maximum in September with a minimum in May.INTRODUCTIONMany seasonal cycles of a physiological nature have been described in the common mussel Mytilus edulis L. (reviewed by Gabbott, 1976; also Pieters et al. 1978; Zurburg et al. 1978), some of which, for example the annual accumulation and subsequent utilization of energy substrates, appear to be linked to gametogenesis. Following spawning in the spring the gonads of Mytilus enter a resting phase; metabolic demands are low. Glycogen and protein are accumulated in the tissues at this time as phytoplankton is abundant. Gonadal development commences in autumn when phytoplankton density has declined and energy is supplied by the utilization of stored reserves. Pieters et al. (1978) have suggested that the resulting decline in reserves is accentuated by the need for greater byssus production at this time to secure the mussels against the rigours of autumn and winter storms. No accounts exist of field studies which might support this hypothesis.
Corophium sextonaein Scottish waters
Authors: Moore P. G. 
Published: May 2009

Recently, I wrote (Moore, 1978) that no substantiated records existed forCorophium sextonaeCrawford amend. Hurley (Amphipoda) north of Abereiddy Quarry, S. Wales. The records of the species for the West coast of Scotland given by Scarratt (1961, Ph.D. Thesis, University of Wales) have been regarded as suspect on the basis of wrongly labelled material from his type collection now (with his kind permission) in my possession. My own investigation of amphipods from kelp holdfasts in the Clyde Sea area and its environs, over many years have failed to produce this species.C. sextonaehas now, however, been identified with certainty from a collection (made on 6 September 1979) ofAscidia mentulaMuller taken from a rope suspended (on 26 April 1979) from the U.M.B.S. raft in Linne Mhuirich, a marine lake off Loch Sween, lat. 55° 59′ N, long 5° 39′ W, O.S. ref. NR732853. Both male and ovigerous femaleC. sextonaewere included in the material. They were living in silty tubes attached to the tests of the ascidians, together withJassa falcata(Montagu) andMicrodeutopus anomalus(Rathke).Personal collections of kelp holdfasts and other algae (Codium, ‘red algal turf’ mostlyBonnemaisonia) in the nearby rapids (ca. 3·2 km distant) at Linne Mhuirich in May 1969 (Moore, 1971, Ph.D. Thesis, University of Leeds) and in June 1974 (Shillaker & Moore, 1978) failed to disclose anyC. sextonae(allCorophiumwereC. bonnellii).C. sextonaemay be very localized within Linne Mhuirich, given Moore's (1978) observations on Lundy; the acknowledged unique hydrography of Linne Mhuirich (Kerr, 1912; Lewis & Powell, i960) and the sensitivity of the species to water movement gradients (Hughes, 1975).
Gill Morphometry of the Mudskipper,Boleophthalmus Boddarti
Authors: Hughes G. M. , Kadhomiy-Al N. K. 
Published: May 2009

Measurements of gill dimensions in relation to body weight have been carried out in a mudskipper,Boleophthalmus boddarti. The data was analysed with respect to body weight using logarithmic transformations (logY= loga + blogW). The slope(b)of the log/log regression lines for the gill area, total filament length, average number of secondary lamellae/mm, bilateral area of an average secondary lamella, and total gill area/g were 1·0496, 0·427, -0·229, 0·851 and 00496 respectively.These results indicate variations in growth patterns for the different dimensions of the gills. The analysis shows that the increase in gill surface area with the body size is mainly due to an increase in the area of individual secondary lamellae and, to a lesser extent, an increase in filament length and total number of lamellae.The average weight-specific area for 14 specimens measured (3·6–35·4 g) was 108–15 mm2/g. This value is consistent with results obtained with some other intertidal species.Marked differences were found in the thickness of the water/blood barrier, which is thinner around the marginal channels. Morphometric diffusing capacity taking this heterogeneity into account was estimated as 0·0208 ml O2min1mmHg−1kg−1.INTRODUCTIONMorphological studies on the gills of many fish have shown adaptations of the basic structure which can be related to the particular mode of life. Among these adaptations, air-breathing species show many remarkable structural modifications (Munshi, 1976), which extend to the gills forming air sacs in species such asHeteropneustes fossilis(Hughes & Munshi, 1979). Fish which inhabit the intertidal zone, like other seashore animals, are subjected to periodic exposure to air, which may produce problems of water loss and reduction in support for the gills, with consequent collapse and restriction of gas exchange surfaces.
Influence of 70 Watt Electric Lights on the Capture of Fish By Otter Trawl Off Plymouth
Authors: Clarke M. R. , Pascoe P. L. , Maddock L. 
Published: May 2009

The effect of two 70 W underwater electric lamps on the catch rate of a commercial bottom otter trawl was determined by comparative trials both at night and in daylight. It was found that, although the overall numbers and weights of fish caught did not differ, most of the species which were caught in large enough numbers for a judgement to be made showed a reaction to light. Three species, Trachurus trachurus, Merlangius merlangus and Trisopterus minutus were attracted and four species, Eutriglagurnardus, Micromesistius poutassou, Merluccius merluccius and Limanda limanda were scared off by light.The possible use of lights to further the development of selective commercial bottom trawling by attracting or scaring particular species is discussed.
The influence of heavy infestations of Polydora ciliata on the flesh content of Mytilus edulis
Authors: Kent R. M. L. 
Published: May 2009

The dry weight condition index and water content of two groups of mussels, one with heavy infestations and the other with mild infestations of Polydora ciliata, were determined over a period of 15 consecutive months. The results were seasonally variable, but for most months the heavily infested mussels had a condition index significantly lower, and a water content significantly higher, than the mildly infested mussels. This suggests that heavy infestations of P. ciliata are associated with reduced flesh content in mussels.Further analyses of the body components of the two groups of mussels, showed that the mantle tissue of heavily infested mussels was reduced much more than the nonmantle tissue. Since the mantle is the main repository of gametes, this suggests that heavy infestations of P. ciliata might lower the fecundity of mussels.
A laboratory study of predation by the dog-whelk Nucella lapillus on the barnacles Elminius modestus and Balanus balanoides
Authors: Barnett B. E. 
Published: May 2009

Predation of the barnacles Balanus balanoides and Elminius modestus by the common dog-whelk, Nucella lapillus was studied in the laboratory. Greater numbers of B. balanoides were taken as prey unless the whelks had been previously subjected to an extensive period of starvation.Selective predation is discussed in the light of similar studies on Nucella and related predatory species. The effects of prey selection on the competitive interactions of the prey species are also considered.The method of predatory attack involves either a drilling or a prizing technique. The latter is used predominantly when Nucella attacks E. modestus, whereas drilling is employed to a far greater extent when attacking B. balanoides. Attacks using the drilling technique are usually made at the occludent margins of the opercular valves.
The reproductive biology of Corophium volutator and C. arenarium (Crustacea: Amphipoda)
Authors: Fish J. D. , Mills A. 
Published: May 2009

The life-cycles of Corophium volutator (Pallas) and C. arenarium Crawford in the Dovey Estuary are based on two generations per year. Reproduction is well established by April and although the overwintering generation dies during the summer, reproduction continues until October as a result of the breeding of summer-generation animals. The mean brood size of C. volutator is greater than that of C. arenarium and both species show high levels of egg loss from the brood pouch. Hatching and moulting of the embryonic cuticle take place simultaneously and the initial rupture of the egg membranes is made by spines on the cuticle of the telson of the future free-living animal. These spines persist throughout post-embryonic life.Adult females of both species show a semi-lunar breeding rhythmicity and, associated with this, adult males show a rhythmic pattern of crawling behaviour. As the tide ebbs during the rising spring tide period, adult males emerge from the sediment and crawl across the mud surface in search of burrows occupied by adult females. It is concluded that copulation takes place in the burrow and not in the water column.
On the structure and behaviour ofFritillaria(Tunicata: Larvacea)
Authors: Bone Q. , Gorski G. , Pulsford A. L. 
Published: May 2009

INTRODUCTIONRather little is known of the behaviour of larvaceans, although they are of great importance in the sea as one of the few groups able to exploit the nanoplankton. Of the two larvacean groups, oikopleurids have received most attention: the behaviour ofOikopleura dioicahas been studied in detail by Gait (1972, Ph.D. Thesis, University of Washington, Seattle), and some notes on the electrical correlates of behaviour have been given by Gait & Mackie (1971) and by Bone & Mackie (1975) forO. dioicaandO. labradoriensis. Much less is known of fritillariid larvaceans and, apart from the brief notes on behaviour by Fol (1872) and by Lohmann (1899) in the course of their classical histological investigations, which were extended by Salensky (1904) and Martini (1909), the only recent investigation of living fritillariids is that of Fenaux (1961) who described the remarkable mode of action of the pyloric cilia.
Occurrence of nematode parasites in Calocaris macandreae (Crustacea: Decapoda) from an Irish Sea population
Authors: Perez-Calderon J. A. 
Published: May 2009

INTRODUCTIONA number of nematodes are known to develop in decapod crustaceans. These parasite nematodes are present in the coelom of the host either free or surrounded by different types of host cells. All belong to the order Ascaridida or Spirurida and most of them develop only to the third larval stage in the decapod host; further development takes place in a predator of the crustacean which is generally a teleost or elasmobranch (Berland, 1961; Ouspenskaia, 1960; Petter, 1970; Poinar & Kuris, 1975;Uspenskaja, 1953; Yamaguti, 1961). The life-cycle in most cases is not fully understood. Ouspenskaia (1960) and Uspenskaja (1953, 1963) deduced the life-cycle for Ascarophis morrhuae van Beneden and A. filiformis Poljanski in the Barents Sea by relating the larvae found in decapod crustaceans through affinity of characters to the adults present in cod (Gadus morhua L.) and haddock (Melanogrammus aeglefinus L.). Similarly, the life-cycle of the spirurid Proleptus obtusus was described by Lloyd (1928); the larvae occur in a decapod crustacean, usually the hermit crab Pagurus bernhardus L. and in some cases the shore crab Carcinus maenas L. and the adults are found in the lesser spotted dogfish (Scyliorhinus canicula L.). A more complex life-cycle has been proposed for some anisakids such as Anisakis, Contracaecum and Hysterothylacium (Berland, 1961; Norris & Overstreet, 1976; Wootten, 1978) in which more than one intermediate host is required.
On the genus Holophryxus (Isopoda: Epicaridea), with description of the male and redescription of the female of Holophryxus acanthephyrae
Authors: Jones M. B. , Smaldon G. 
Published: May 2009

INTRODUCTIONAdults of the isopod genus Holophryxus (Dajidae) occur as ectoparasites on natant decapod crustaceans, but little is known of the ecology and life-history of most species. Species of Holophryxus are thought to have a typical dajid life cycle involving an intermediate host (copepod), a definitive host (prawn) and three larval stages (epicaridium, microniscus, cryptoniscus), and the one species for which details are available fits this pattern (Coyle & Mueller, 1981). The final host is infected by the cryptoniscus, a stage superficially resembling a cirolanid isopod, and the first cryptoniscus to settle loses its isopod-like appearance and develops through a juvenile stage into a rather inflated, highly modified female (Coyle & Mueller, 1981). Any subsequent settler becomes a male, retains the small cryptoniscus body form and lives within the marsupium of the female.
Size data and stomach contents of common dolphins, Delphinus delphis, near Plymouth
Authors: Pascoe P. L. 
Published: May 2009

INTRODUCTIONThe laboratory at Plymouth was notified of the capture of five dolphins in a commercial trawl on 9 December 1982, three of the specimens were living and therefore immediately released. The remaining two were brought to the laboratory, identified as Delphinus delphis Linnaeus, 1758, their size and sex were recorded and the stomachs removed for examination of their contents. The exact location of capture was not recorded, but is known to be within 40 miles of Plymouth.Reports of strandings of D. delphis collected by the British Museum (Natural History), (Harmer, 1914–27; Fraser, 1934, 1946, 1953, 1974) and more recent recorded sightings (Evans, 1980) show that the common dolphin is clearly not rare in British waters. Although the species has been recorded off all British coasts, sightings and strandings are concentrated off the south and south-west coasts of Britain and Ireland. The variation in their numbers and distribution both during this century and on a seasonal basis each year has been accounted for mainly by the fluctuation and movement of their food supply (Evans, 1980; Sheldrick, 1976).