bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mitotic E- and Secretory F-Cells in the Hepatopancreas of the Shrimp Penaeus Semisulcatus (Crustacea: Decapoda)
Authors: Al-Mohanna S. Y. , Nott J. A. , Lane D. J. W. 
Published: May 2009

INTRODUCTIONIt is apparent, in a review on the decapod hepatopancreas (Gibson & Barker, 1979) that there is some consensus of opinion that the epithelium consists of E-, R-, F- and B-cells and M-cells (Al-Mohanna, Nott & Lane, 1985). Also, it is agreed that the gland produces enzymes and absorbs, digests and stores nutrients and excretes waste material. However, the apportionment of these functions to the different cells and the descriptions of the cytological processes involved are variously explained. Thus, the activity of proteases and amylases has been demonstrated in the secretion produced by the gland but the source of these enzymes is attributed to different cells and various modes of secretion are proposed. Also, no secretion granules of the zymogen type have been seen.There are probably two main reasons for the inconsistent interpretation of the activities of the cells. First, the different stages of the feeding and moult cycles are not taken into account and both these affect the cytology of the gland. Second, some of the functions have been deduced from observations of the fine structure without any experimental treatments to demonstrate more directly the processes involved. In the present work all the animals are taken at the same moult stage and observations are made throughout the feeding cycle. Also, aspects of the function are studied with markers which are administered in the diet and injected into the blood. The activities of hydrolytic enzymes associated with the different epithelial cells have been studied but these will be the subject of a separate publication dealing with the cytochemistry of the digestive processes.
Vascular and Pericardiac Pressures inAscidiella Aspersa(Urochordata: Ascidiacea)
Authors: Jones H. D. 
Published: May 2009

INTRODUCTIONThe heart of tunicates is of physiological interest for several reasons: it is a simple peristaltic tube; it lacks valves; and the direction of the contractions changes periodically thus reversing the direction of blood flow. The phylogenetic importance of tunicates, being invertebrate chordates, also make physiological details of interest.
Calorific Values and Elemental Analysis of Eleven Species of Oceanic Squids (Mollusca:Cephalopoda)
Authors: Clarke A. , Clarke M. R. , Holmes Lesley J. , Waters T. D. 
Published: May 2009

INTRODUCTIONCephalopods may be divided into five types according to their buoyancy. Members of several families such as the Octopodidae, Loliginidae and Ommastrephidae are negatively buoyant and must swim to stay in midwater and are therefore highly muscular animals. Others have mechanisms to make them neutrally buoyant so they can remain suspended in midwater without effort. Nautilus, Spirula and cuttlefishes have low pressure gas-filled chambers and their flesh is muscular and non-buoyant (Denton & Gilpin-Brown, 1973). Squids of one family, the Gonatidae, have a low density oil in their livers to give buoyancy but most of their body is muscular. Some oceanic octopods have very watery tissues in which lighter chloride ions replace sulphate ions (Denton & Shaw, 1961). In 12 of the 26 teuthoid families the buoyancy is provided by low-density ammonia-rich solution in their body and head tissues or in an expanded coelomic cavity (Clarke, Denton & Gilpin-Brown, 1979). These ammoniacal squids are extremely abundant in the oceans of the world and form a large part of the diet of birds, cetaceans, seals and fish (Clarke, 1977). When their biomass is estimated from their utilization by predators it is important to know their properties as food and, in particular, their calorific values. As pointed out by Croxall & Prince in a review of the calorific values of cephalopods (1982), all the known values are of muscular, negatively buoyant species because they are of value as food for humans but no measurements have been made on the ammoniacal or oily species which are probably as important, or even more important, in the economy of the ocean (Clarke, 1983).
Faunas Associated with Longitudinal Furrows and Sand Ribbons in a Tide-Swept Area in the English Channel
Authors: Holme N. A. , Wilson J. B. 
Published: May 2009

INTRODUCTIONIn the central regions of the English Channel surface tidal streams are strong, often exceeding 160 cm s−1 at peak springs, with maximum values of over 250 cm s−1 off the headlands of Portland Bill and Cap de la Hague (Sager & Sammler, 1975). Correspondingly high values for bottom stress (Pingree & Griffiths, 1979) result in a scoured sea-bed covered with a minimum of sediment, the underlying bedrock being exposed in places. Study of current-generated bedforms in relation to the prevailing tidal currents has indicated the presence of a bed-load parting zone across the Channel from the Isle of Wight to Cap de la Hague (Stride, 1963; Johnson et al. 1982).
Direct Observation of Sex Change in the Patellacean Limpet Lottia Gigantea
Authors: Wright William G. , Lindberg David R. 
Published: May 2009

Protandric hermaphroditism, the sequential change from male to female, has been reported in several superfamilies of prosobranch gastropods including the Fissurellacea, Patellacea, Calyptraeacea, and Eulimacea (Webber, 1977). It is most common in members of the Calyptraeacea and the Patellacea. In the Calyptraeacea changes in sex are readily followed by observing copulative structures (Coe, 1944). Because patellacean limpets are predominantly broadcast spawners with external fertilization, external characters that can be used to determine the sex of individuals are rare. Hence, previous to this report the occurrence of protandry in most patellacean limpets has been based primarily on sexual dimorphism in size; the smaller size classes being made up of male individuals and the larger size classes of female individuals (Willcox, 1898; Orton, 1920, 1928; Orton, Southward & Dodd, 1956; Dodd, 1956; Branch, 1974). However, given this type of data it is often difficult to assess whether the observed sexual dimorphism is indicative of protandry or merely a result of differential growth and/or survival. The presence of simultaneous hermaphrodites in the intermediate size classes, as evidence of protandry is of limited value because simultaneous hermaphrodites occur sporadically in patellaceans that do not show a sexual dimorphism in size (Dodd, 1956; Branch, 1974). The only unambiguous way of proving the existance of protandry in patellacean limpets is the direct monitoring of gonadal changes in individuals through time. We report here the first direct observations of protandric hermaphroditism in a patellacean limpet.Lottia gigantea Sowerby, 1834 is a large (100 + mm), territorial, intertidal limpet that ranges from northern California to central Baja California, Mexico (Stimson, 1970).
The Reproductive Biology ofOphiacantha Bidentata(Echinodermata: Ophiuroidea) From The Rockall Trough
Authors: Tyler P. A. , Gage J. D. 
Published: May 2009

INTRODUCTIONOphiacantha bidentata(Retzius) is a widespread arctic-boreal ophiuroid with a circumpolar distribution in the shallow waters of the Arctic seas and penetrating into the deep sea of the.North Atlantic and North Pacific (Mortensen, 1927, 1933a; D'yakonov, 1954). Early observations of this species were confined to defining zoogeo-graphical and taxonomic criteria including the separation of deep water specimens as the varietyfraterna(Farran, 1912; Grieg, 1921; Mortensen, 1933a). Mortensen (1910) and Thorson (1936, pp. 18–26) noted the large eggs (o.8 mm diameter) in specimens from Greenland and Thorson (1936) proposed that this species had ‘big eggs rich in yolk, shed directly into the sea. Much reduced larval stage or direct development’. This evidence is supported by observations ofO. bidentatafrom the White and Barents Seas (Semenova, Mileikovsky & Nesis, 1964; Kaufman, 1974)..
Taxonomic Studies on British and Irish Amphipoda. the Genus Gammaropsis
Authors: Myers A. A. , Mcgrath D. 
Published: May 2009

INTRODUCTIONLincoln (1979) stated that ‘four species (of Gammaropsis Liljeborg) are reported from the British Isles, Gammaropsis maculata (Johnston), G. palmata (Stebbing & Robertson), G. nitida (Stimpson) and G. sophiae (Boeck)’. In fact, six species of Gammaropsis have been reported from the British Isles in the literature, the records of G. lobatus (Chevreux) (Spooner, i960) and G. melanops (Sars) (Jones, 1948) having apparently been overlooked by Lincoln (1979). Spooner's (1960) material is apparently no longer extant, but the material attributed to G. melanops by Jones (1948) has been re-examined by us and found to be referable to G. lobata. Recent collections of G. lobata from the west coast of Ireland confirm a rather wide distribution of this species in the southwest of these islands.Five species of Gammaropsis are therefore now known from these islands, and G. melanops can, at least for the present, be deleted from the British and Irish list of species.Lincoln (1979) was unable to examine any British material of G. sophiae, everything labelled as such, in the material examined by him (including the Norman collection at the B.M.N.H.)* being referable to G. nitida. He therefore figured the species from West African material. G. sophiae is quite widespread along the southwest coast of Ireland and since it differs somewhat from the material described by Lincoln (1979) it is figured herein from the Celtic Sea.Krapp-Schickel & Myers (1979) reviewed the Mediterranean species of Gammaropsis and segregated the species into two groups, group ‘A’ species characterized by the possession of a toothed urosome, toothed coxa 1 and long acute epistome, and group ‘B ‘ species characterized by having a smooth urosome, smooth coxa 1 and short epistome.
The Role of the outer Conducting Epithelium in the Behaviour of Salp Oozooids
Authors: Bone Q. 
Published: May 2009

INTRODUCTIONBoth the inner and outer epithelia of salps propagate action potentials (Mackie & Bone, 1977). Skin pulses in the outer epithelium underlying the test (OSPs) evoked by mechanical or electrical stimulation of the epithelium ‘enter’ the brain and may alter the regular rhythmic locomotor activity (Mackie & Bone, 1977; Andersonet al.1979). The route of'entry’ has not been determined, but has been assumed to be via the axons of the scattered mechanoreceptor sensory cells lying in the outer epithelium. The OSP system would thus operate to extend the sensory field of such cells, as in the appendicularianOikopleura(Bone & Mackie, 1975; Bone & Ryan, 1979) where two sensory cells are coupled to a conducting epithelium.Salps alternate generations between the solitary asexual oozooid, and the aggregated sexual blastozooids (budded from the stolon of the oozooid). The linked blastozooids form chains, along which OSPs pass to regulate the locomotor behaviour of individual zooids in the chain. The zooids are not linked by gap junctions, and OSPs pass along the chain in a complex.manner, involving alternating epithelioneural and neuroepithelial synapses (Bone, Anderson & Pulsford, 1980; Anderson & Bone, 1980). The OSP system of the oozooid generation is less well understood, although it is known that OSPs in the outer epithelium of the oozooid propagate into the stolon, where they have been studied by Anderson (1979). This paper shows that oozooids possess a similar system of neuroepithelial synapses to that of blastozooids, and that these ‘ drive’ OSPs in the same way as occurs during the regenerative transmission of OSPs along the blastozooid chain.
An Analysis of Factors Determining Seasonal Variation in the Byssal Attachment Strength of Mytilus Edulis
Authors: Price H. A. 
Published: May 2009

INTRODUCTIONThe common mussel Mytilus edulis L. is one of the most successful shore molluscs. It is widely distributed in the northern hemisphere and is abundant not only in the most sheltered bays and loughs but also in conditions of extreme exposure (Lewis, 1964; Seed, 1976). Attachment to the substratum is by means of the proteinaceous byssus complex, the strength of which has been shown to vary seasonally (Price, 1980b). This variation could be a response to seasonal fluctuations in wave action, as suggested by Pieters et al. (1978), or may result from the seasonality of other environmental variables. Some of these, e.g. salinity and sea temperature, have been shown to influence byssus production (Glaus, 1968; Van Winkle, 1970; Allen et al. 1976), Phytoplankton density, spawning and the reduced ‘scope for growth’ during winter months (Bayne & Widdows, 1978) may also play a role in determining byssus strength.In the present study, the relationships between byssal attachment strength and environmental and other variables are examined in a population of mussels on the South Wales coast.
Growth of the Queen Scallop Chlamys Opercularis in Suspended Cages in the Firth of Clyde
Authors: Richardson C. A. , Taylor A. C. , Venn T. J. 
Published: May 2009

INTRODUCTIONEstimations of the growth of bivalves have traditionally been determined from measurements of animals collected on a regular basis from natural populations. Generally size frequency distributions have been analysed or growth rates estimated from measurements of the distances separating the annual rings (Hughes, 1970; Seed & Brown, 1978; Taylor & Venn, 1978). While both methods provide valuable information on shell growth, a more direct approach is to investigate experimentally the growth of individual animals held in cages and to follow the seasonal changes in the dimensions of their shells.The queen scallop Chlamys opercularis (L.) is found in large numbers in areas around Great Cumbrae Island in the Firth of Clyde where they form the basis for a small local fishery. In 1979 the British Steel Corporation started operating a deep-water terminal at Hunterston unloading and loading iron ore and coal. It was envisaged that accidental spillage of material during transfer from the vessels to the shore might affect the queen scallop populations in the area.
Speed Sensing in a Harbour Seal
Authors: Renouf Deane , Gaborko Linda 
Published: May 2009

Many pinnipeds travel long distances between breeding and feeding grounds in some cases showing remarkable homing abilities (James & Dykes, 1978). Very little is known about the methods they use to plot their course but if they were aware of their rate of movement, this ability could conceivably assist them. The following procedure which was undertaken with a captive male harbour seal (Phoca vitulina Linnaeus) demonstrated that the animal was able to determine his swimming speed.The seal was first trained to swim at any speed through ten hoops 48 cm in diameter submerged at equal intervals around the periphery of an 8 m oval tank filled with sea water to a depth of 1.2 m. Each trial consisted of one circuit of the tank, and always began at the same hoop. A screen preventing the seal from going through this start hoop was removed to indicate the onset of each trial. The seal was then trained to swim the 17 m course maintaining a speed of 6 km/h. The experimenter observed from a bridge suspended over the tank, and measured the animal's speed by listening to a series of tones. These tones were audible only to the experimenter and were timed such that if the seal were swimming at 6 km/h, he would reach each hoop at the same moment the experimenter heard the tone. A buzzer was sounded whenever the animal swam at less than the required speed, and a whistle was blown if he were moving too quickly.
Two Species of Algal Symbiont in Naturally Occurrin G Populations of Convoluta Roscoffensis
Authors: Mcfarlane A. E. 
Published: May 2009

Convoluta roscoffensis (Graff) has long been known for its symbiosis with a green flagellate definitively described from French stock as Platymonas convolutae by Parke and Manton (Parke & Manton, 1967). Provasoli subsequently discovered a species of Prasinocladus in a culture isolated from C. roscoffensis, but concluded that it was a surface contaminant of the animal (Provasoli, Yamasu & Manton, 1968).Populations of C. roscoffensis from Aberthaw, South Wales (Mettam, 1979), and eighteen sites on Guernsey have been studied. In most patches of the Aberthaw colony, and in two of the Guernsey sites, two algal symbionts have been found. One of the Guernsey, and one of the Aberthaw symbionts appear identical to Platymonas convolutae.They can be distinguished at the ultrastructural level by the presence of canaliculi which penetrate the pyrenoid, and are lined with the double-layered plastid envelope. In both cases the second flagellate shows the nucleus-pyrenoid complex typical of the genus Prasinocladus, where the nucleus penetrates the pyrenoid, and a pair of thylakoid membranes separate the pyrenoid from the starch shell (Parke & Manton, 1965). Neither symbiont has been identified specifically.It is also possible to distinguish the two symbionts in the living animals, since the cup-shaped pyrenoid of the Prasinocladus type is easily distinguished from the spherical condition in Platymonas using the light microscope. A mixed population of symbionts has never been found in an individual worm. For each patch of animals in a colony it was possible to establish the percentage of animals containing each symbiont. This ratio varies from patch to patch in the colony, but has remained remarkably constant within each patch over the six months it has been studied. The Prasinocladus type always predominates at Aberthaw, the Platymonas type being absent in places.
The microanatomy ofHymenomonas lacunasp.nov. (Haptophyceae)
Authors: Pienaar Richard N. 
Published: May 2009

A new species ofHymenomonasStein,Hymenomonas lacunasp.nov. from San Juan Island, Washington, U.S.A. is described using light and electron microscope techniques. The cells normally occur in non-motile clumps growing on the sides of the culture vessel. Each cell has a body covering composed of a single layer of coccoliths of unusual construction and several layers of circular unmineralized rimless scales. Occasional small elliptical scales are sometimes found.The general cytology of the cells is discussed with special attention paid to the unusual pyrenoid and the role of the Golgi body in scale and coccolith production.The relationship of this species toH. roseolaStein is discussed.
An assessment of the basis of mercury tolerance inDunaliella tertiolecta
Authors: Davies Anthony G. 
Published: May 2009

The specific growth rate ofDunaliella tertiolectawas unaffected by mercury II concentrations of at least 2.03 μg at/1. At 10 μg at/1, it was eventually reduced by 84% but growth continued, giving a final level of cell material only 13% below that in a mercuryfree control. At this concentration, however, growth was largely uncoupled from division and giant cells were produced, probably due to the effect of mercury upon the production of methionine which is known to be implicated in the process of cell division.The basis of the mercury tolerance was investigated in terms of (1) mercury detoxication in the culture medium by complex or compound formation between the metal and metabolites produced by the cells, (2) the concentration of sulphydryl groups both within the cells as possible sequestration sites and in the cell membrane where any molecular disruption and permeability changes produced by the metal first occur, (3) the absence of cellular potassium leakage and (4) the resistance of the cell membrane to the uptake of mercury II ions. Where possible, the results were compared with those from determinations of the same properties of the mercury-sensitive speciesIsochrysis galbana. The experiments indicated that the mercury tolerance ofD. tertiolectais partly related to the slower rate of mercury accumulation by this species, but is largely due to the detoxication of the mercury within the cell possibly by the precipitation of a highly insoluble mercury compound
Defensive behaviour of sea anemones in response to predation by the opisthobranch molluscAeolidia papillosa(L.)
Authors: Edmunds M. , Potts G. W. , Swinfen R. C. , Waters V. L. 
Published: May 2009

The defensive behaviour of 11 species of sea anemone when attacked by the nudibranchAeolidia papillosais described. An attempt is made to correlate their defensive responses with the habitat, and with the food preferences ofAeolidia. Actinia equinaresponds first by tentacle and column retraction, and then by inflation of the column, pedal locomotion, and detachment from the substrate.Anthopleura elegantissimaresponds in similar ways, butAnemonia sulcata, which has much longer tentacles, uses these in active defence against the eolid.Anemoniaalso crawls away but it does not detach.Actinia, AnthopleuraandAnemoniaare the preferred foods ofAeolidia. They commonly live in dense colonies where locomotion and detachment are likely to result in escape.Tealia felinais less preferred and is much less responsive when attacked byAeolidia.Anemones which possess acontia normally eject these when they are attacked byAeolidia. AlthoughAeolidiadoes occasionally eat acontian anemones, evidence is presented which suggests that acontia have some deterrent effect on this predator. Although most acontian anemones are probably able to move by pedal locomotion and to detach from the substrate, these responses are much less frequently given than byActinia equina.
Salinity preference in gammarid amphipods with special reference toMarinogammarus marinus(Leach)
Authors: Bettison Jane C. , Davenport John 
Published: May 2009

The salinity preferences of the amphipods studied were found to correlate with distribution.Marinogammarus marinus, a marine species, showed a strong preference for higher salinity levels, the estuarineGammarus duebenishowed little avoidance of any particular sea water concentration, and the freshwaterGammarus pulexdisplayed strong preference for dilute mediaTolerance experiments showed that the preference behaviour ofM. marinuswas not caused by lethal effects of salinity.Observations onM. marinussuggested that the behaviour involved components of both preference and avoidance.InM. marinusthe choice is made on the basis of total osmolarity of the medium, not on its organic or ionic content alone.Ablation of the upper and/or lower antennae had no effect on salinity choice inM. marinus, and acclimation to 50% sea water did not alter the preference for full sea water.It is suggested that behavioural responses which confine animals to areas well within their physiological salinity limits promote survival in aquatic environments which may undergo fluctuations in salt concentration.
Notes on the flagellar apparatus and taxonomy of Pavlova mesolychnon Van der Veer, and on the status of Pavlova Butcher and related genera within the Haptophyceae
Authors: Green J. C. 
Published: May 2009

INTRODUCTIONPavlova gyrans Butcher, the type species of the genus, was described at the light microscope level in 1952 (Butcher, 1952). Since then this species has been re-investigated with the electron microscope (Green & Manton, 1970), a number of other species described from marine, brackish and freshwater habitats (for literature, see p. 600) and at least two new genera erected which appear to be closely related to Pavlova (Corcontochrysis Kalina, 1970;Exanthemachrysis Lepailleur, 1970).
Feeding, growth and reproduction of the marine planktonic copepod Temora longicornis Müller
Authors: Harris R.P. , Paffenhöfer G.-A. 
Published: May 2009

INTRODUCTIONThe copepod Temora longicornis Miiller is one of the common zooplankton species in the North Sea and adjacent waters. All developmental stages have been recorded throughout the year off the west coast of Sweden, Temora being considered more common in offshore than inshore waters (Eriksson, 1973). In Loch Striven on the west coast of Scotland it was abundant only in summer, living mainly near the surface (Marshall, 1949). Similarly in the English Channel off Plymouth Temora is present mainly during the summer months (Digby, 1950). T. longicornis was found throughout the year in the Northfrisian Waddensea with temperatures ranging from ca. 1–20 °C (K¨nne, 1952).