bluuebunny/crossref_metadata_2025 huggingface dataset:
The Physiology of Maturation and Fertilization inPomatoceros Triqueter(L.) I. The Nature of the Material
Authors: Cragg J. B.
Published: May 2009

The description of the material used in the present investigation does not conform with that of Horstadius. Attention is drawn to this lack of agreement. A hypothesis based on viscosity changes within the egg has been advanced to explain the rounding off of eggs in sea water.

By means of what is called the transfer series the egg batch has been divided into a number of parts; the last liberated eggs being the ripest. The occurrence of large numbers of egg batches giving low maturity values has been attributed to maturity resulting from a series of changes whose rate after initiation gradually increases.

Attention is drawn to seasonal changes in the reactions of the germinal products. No definite lunar periodicity is shown in the ripening of the eggs.
The Biology ofChthamalus Stellatus(Poli)
Authors: Moore Hilary B. , Kitching J. A.
Published: May 2009

Chthamalus stellatus is a littoral barnacle very similar in habitat and general ecological relations to another littoral barnacle, Balanus balanoides. In those localities where both species flourish they compete considerably for space, and also possibly for food. The fact that B. balanoides settles sooner after the winter storms than does Chthamalus probably favours the former.

Chthamalus is characteristically a southern species and Balanus balanoides a northern one, but the north and south ranges of the two species overlap in the British Isles and in France. The determining factor is presumably temperature.

Chthamalus is an Atlantic species, and Balanus balanoides is more characteristically a North Sea species. The essential factor in Atlantic water remains unknown, although in respect of a need for Atlantic water Chthamalus resembles Sagitta elegans and intertidalEchinus esculent.
Observations on Flounders Pleuronectes Flesus L. Marked in the Esturaries of the Tamar and Lynher
Authors: Hartley P. H. T.
Published: May 2009

1039 flounders were marked with numbered vulcanite disks in the estuaries of the Tamar and Lynher.

148 flounders were recaptured and of these seven fish were recovered a second time after one recovery and release, and one fish was recaptured on three occasions after two previous recoveries and releases.

Only two fish were recovered at a distance from Plymouth. Both had moved eastward, up the English Channel.

There was little or no growth in the winter months.

Individual growth rates were found to vary greatly.

The flounders living in the last reach of the Tamar near Saltash tended to remain in one limited area during the winter months, save for a drift down-stream of some of the larger fish. In the spring there was an upstream movement of the smaller, immature fish.

Flounders which had gone down to the sea to spawn might return to the river in which they were marked, or to the other river of the two which join to form the Hamoaze, or they might move right away from the area where they were marked.
Some Notes on Parasitic Copepoda
Authors: Gurney Robert
Published: May 2009

The Lernaeopodidae are a highly specialized group of parasitic Copepoda presumably derived from a Caligoid stem, and some clue to their systematic position should be found in their development. Some stages are known in ten genera, but it is only in Achtheres, Salmincola, and Clavella that the whole, or nearly the whole, series of stages has been described. There is a very strong tendencyto suppress the nauplius as a free stage though, when so suppressed, there may be moults corresponding to nauplius and metanauplius (Zandt, 1935). In some species there is certainly a free nauplius, but it probably moults into the copepodid in a very short time.
The Portuguese Man-of-War, Physalia Physalis L., in British and Adjacent Seas
Authors: Wilson Douglas P.
Published: May 2009

The occurrence in the summer of 1945 of a swarm of Physalia physalis L. off the south-west coast of the British Isles has initiated a survey into records of its appearance on the Atlantic coasts of Europe during the past 100 years. Unpublished records for 1912, 1913, 1934 and 1935 were discovered and are listed with those already known. The 1945 strandings are considered in detail in conjunction with meteorological data for the period involved. It is concluded that winds, rather than water movements, are the main factor in transporting the swarms towards the British Isles and it is considered likely that the swarms come from the Azores-mid-Atlantic region rather than from the Canaries-Gibraltar district.

Associated with the Physalia were Lepas fascicularis and L. pectinata, some Velella, a few turtles (Caretta caretta), and possibly an Opah fish (Lampris luna), all of them, with some reservation respecting the last-named, surface organisms that would come under the same meteorological influences as the Physalia.

A living specimen of Physalia gave an opportunity to observe the method of feeding of which few previous first-hand accounts exist. The capture of the prey by the dactylozooids and its subsequent digestion by the gastrozooids is illustrated by photographs from life and is described in some detail. It is suggested that the rolling of the pneumatophore from side to side, dipping the crest in the water, is a calm-weather habit directed to keeping moist the upper surface exposed to the air.
New Observations on the Distribution and Morphology of the Amphipod,Gammarus ZaddachiSexton, With Notes on Related Species
Authors: Segerstråle Sven G.
Published: May 2009

As is well known, the speciesGammarus zaddachi, established by E. W. Sexton in 1912 on material from European brackish and fresh-water localities, has caused great confusion among zoologists, as the characteristics distinguishing it from various related species, particularlyGammarus locusta, G. duebeniandG. pulex, have been very frequently disregarded. This confusion still persists to-day—that is amply shown by the material received for the present investigations from various museums.
On the Biology and Relationships of the LamellibranchXylophaga Dorsalis(Turton)
Authors: Purchon R. Denison
Published: May 2009

The exhalant siphon ofXylophagais greatly reduced and its opening is situated within the burrow. Faeces accumulate in the posterior end of the burrow in a compact mass.

The ctenidia and labial palps ofTeredo, BankiaandXylophagaare modified and reduced, unlike those of the Pholadidae. The ctenidia are flat and homorhabdic and possess no ciliary sorting mechanisms; they consist of the outer demibranch only.

The ctenidia ofXylophagaare composed of a direct lamella; those ofTeredoandBankiaare divided into anterior and posterior portions connected by a branchial groove which is an extension of the marginal food groove of the gill. The number of filaments in the anterior portion of the gill varies according to the species, and is of assistance in identification.

The labial palps ofTeredo norvegicaare least reduced; inXylophaga dorsaltsreduction is greater, though selection of food material is still exercised. The greatest reduction has occurred inTeredo megotaraand inT. navaliswhere there is no selection.

The ciliated mantle tracts inTeredoand inXylophagaplay an important part in limiting the quantity of food particles passed from the ctenidia to the mouth.
The Biology and Trematode Parasites of the GastropodLittorina Neritoides(L.) on the Plymouth Breakwater
Authors: Lysaght Averil M.
Published: May 2009

An account is given of the distribution, life history and trematode parasites ofLittorina neritoideson the Plymouth Breakwater; a few observations from other localities are included.

The smaller snails are most abundant on the exposed southern slopes of the Breakwater. Many of the larger ones live more or less permanently in water in small cylindrical pits on the top of the Breakwater. This habitat is apparently very similar to that described by Fischer-Piette (1932) as occupied permanently by this species at Cap Martin; Lebour (1935) has sometimes found it in water in other places in the Plymouth area.

The conditions necessary for metamorphosis of the larvae, the need of the adults for shelter from the force of the waves, and the requirements for spawning appear to be of more importance in determining the choice of habitat than the negatively geotactic and varying phototactic responses found in this species by Fränkel (1927).

The breeding season lasts from September to April. The males are ripe about two months before most of the females. Experimental evidence is given which makes it most improbable that there is any downward migration for spawning. From the examination of plankton samples it appears that there is a fortnightly spawning rhythm coincident with high tides, and that even the snails living in water discharge their eggs only at these periods.

The distribution of the size groups is discussed. The proportion of males decreases significantly in the larger size groups and it is probable that there is a difference in the growth-rate of the sexes.
Observations on the Night Tidal Migrant Crustacea of Kames Bay
Authors: Watkin E. Emrys
Published: May 2009

The faunal analysis of forty-eight samples taken with a coarse tow-net across the intertidal waters of Kames Bay during 1936 shows that the night migrant crustacean population falls into two well-marked groups: (a) those species which live in the intertidal sand and perform simple vertical migrations at night-time into the intertidal waters, and (b) those which are carried in by the tide into the intertidal area from various habitats which lie beyond the low-water mark of spring tides. In the former group the species of the genera Bathyporeia and Pontocrates are dominant and they retain their zonation as migrants, the population consisting of individuals in all stages of maturity. This is in sharp contrast to the latter group, typified by Gammarus locusta and Idotea viridis, which occur over the whole tidal range with a population in which the young immature stages are dominant. The Haustoriids Urothoë brevicornis and Haustorius arenarius occur as inhabitants of the sand, the former appearing occasionally in the tow-net samples and the latter absent from them. The Cirolanid Eurydice pulchra performs both day and night migration for the purposes of feeding.

Discussion of the results indicates the lines along which further investigations may be carried out.
The Occurrence and Breeding of Sagitta Elegans Verrill and Sagitta Setosa J. Müller in Parts of the Irish Sea
Authors: Pierce E. Lowe
Published: May 2009

An investigation has been made of the species of Sagitta present in parts of the Irish Sea, their relative occurrence, and the annual number of reproductive cycles of each species. Three stages of maturity as described by Russell (1932a) have been used. To determine the maturity the Sagitta were transferred to a solution of 75% alcohol and stained with borax carmine.

S. elegans Verrill and S. setosa J. Müller were collected in Liverpool Bay and in Port Erin harbour, Isle of Man. The former species was predominant at Port Erin. The coasts of Liverpool Bay have been added to the permanent range of S. setosa.

At Port Erin there appears to be but one chief spawning period for S. elegans which extends generally from January through May. Following May the young forms appear in numbers and gradually mature through December to repeat the annual cycle.

There appear to be two main breeding seasons for S. setosa in the outer Mersey Channels. The first and most noticeable begins in April and extends into June. There is evidence for a second breeding period in August.

Both species were found in the samples taken from Morecambe Bay and Anglesey. The stage of maturity of these agreed with the Sagitta caught at the same time at Port Erin and Liverpool.

The total monthly catches of Sagitta from Port Erin and the outer Mersey Channels have been recorded.
The Larval Stages of Portumnus (Crustacea Brachyura) with Notes On Some Other Genera
Authors: Lebour Marie V.
Published: May 2009

Two species of Portumnus occur in the Plymouth area, P. biguttatus (Risso) and P. latipes (Pennant). P. biguttatus was the only species recorded when the old fauna list of Plymouth was published (1904), but since then it is known that P. latipes is very common in certain sandy areas (see Plymouth Marine Fauna, 1931), far commoner than P. biguttatus.

P. biguttatus is rare and has not been seen since 1906. It was first found by W. Garstang and R. Todd on Drake's Island in Plymouth Sound, burrowing in fine gravel (1905), and two specimens, and are recorded from a sandy patch from the north-east corner of Drake's Island. A female in berry was recorded from the same locality by R. Todd, and L. R. Crawshay dredged one in Cawsand Bay in 1906. Apparently the eggs were not hatched out and the zoea of this species is unknown. In August 1902 R. Gurney obtained a megalopa in the plankton and from it secured the first crab stage. He describes the megalopa as being intensely blue. The cast skin of the megalopa and the crab obtained from it (Fig. 3a-c), which he kindly handed to me, are described in my paper of 1928 (Lebour, 1928c, p. 518, pl. viii, figs. 1–3). There is no reason to doubt the accuracy of the determination, especially because, as shown below, corresponding stages of P. latipes as well as the zoeae are now known and are very distinct, differing considerably from those of P. biguttatus.
Structure and Function of the Gut inSpadella CephalopteraandSagitta Setosa
Authors: Parry D. A.
Published: May 2009

Spadella cephaloptera

1. The oesophageal epithelium is composed of granular and vacuolated cells. The former produce a glutinous secretion which appears to immobilize and lubricate the prey. The function of the vacuolated cells remains undetermined.

2. The intestinal epithelium is composed of gland cells and absorptive cells. The gland cells contain large vacuoles which disrupt when food is taken, restitution taking several hours. The absorptive cells accumulate large concretions of fat and other material as digestion proceeds; later this gradually disappears.

3. The absorptive cells in the intestine are ciliated. The cilia may be concerned with respiration and excretion; there is no evidence that they are concerned with osmoregulation.

4. The rectum has a ciliated columnar epithelium.

5. The general course of feeding and digestion,is discussed.

6. It is stated in a footnote that the reproductive system ofSpadellais similar to that ofSagitta.

Sagitta setosa

7. The oesophagus is divided histologically as follows: (i) a region of granular cells round the mouth; (ii) a region of vacuolated cells; (iii) a region of compound granular cells; (iv) a second region of granular cells. The granular cells produce a profuse secretion with probably the same function as the glutinous secretion inSpadella.

8. The intestinal epithelium is composed of compound granular cells and simple columnar cells. By comparison with the intestine ofSpadellathe former are regarded as enzyme-secreting cells and the latter as absorptive.
Methods of Surveying Laminaria Beds
Authors: Chapman V. J.
Published: May 2009

Previous methods of survey by American workers are described and the differences between the species of seaweed involved are emphasized. The small stature of the European kelps renders all methods of survey difficult and the results can only be described as the best approximations. The British survey was divided into (1) a preliminary survey in order to determine the regions with the biggest beds, and (2) a detailed survey, when some of these major beds were mapped in detail. The primary survey was a rapid affair and the results were based on information obtained from (a) use of boat and grapnel, (b) existence of cast weed, (c) lobster fishermen, (d) coastguards, fishery officers, borough surveyors, harbour-masters, (e) inspection from cliffs, (f) a study of Admiralty Charts.

In the section on the detailed survey the different types of grapnel employed and also the method of using the box sextant are described. The use of an echo-sounder to locate weed beds is discussed and the different types of record obtained over various types of bottom or weed are noted. The use of a viewbox and personal observation is also mentioned, and finally an account is given of aerial photography as a means of survey. The most suitable conditions for success are noted and also the technique of interpretation for both oblique and vertical photographs. The plotting of these two types of photograph is described in some detail.
Studies in the Physiology of Commensalism. IV. the Polynoid Genera Polynoë, Lepidasthenia and Harmothoe
Authors: Davenport Demorest
Published: May 2009

The host-response of the polynoid Polynoë scolopendrina Savigny, commensal with the terebellid Polymnia nebulosa (Montagu), is relatively specific within the family Terebellidae.

Evidence is presented that an unstable or closely bound attractant is present on the outside of the host and perhaps in tube material, but apparently absent in the mucus secreted by the host. Efforts to demonstrate its presence in ground-up whole host resulted in failure.

The polynoid Lepidasthenia argus Hodgson demonstrates a similar specificity of response to its host Amphitrite edwardsi Quatrefages.

The polynoid Harmothoë spinifera Ehlers, commensal with Amphitrite gracilis Grube, responds to the alternate host Polycirrus caliendrum Claparede as strongly as to its own host, and more strongly than to other species of Amphitrite. Likewise, Polynoë scolopendrina, commensal with Polymnia, responds with greater intensity to the alternate host, the eunicid Lysidice ninetta Audouin and Milne-Edwards, than to any non-host terebellid. This behaviour may be i terpreted as evidence that the specificity of at least some single commensal species for hosts which are not closely related to each other may depend upon the production of similar attractants by these hosts.

The responses of three commensal populations of Harmothoe lunulata (Delle Chiaje), commensal respectively with the ophiuroid Acrocnida brachiata (Montagu), the holothurian Leptosynapta inhaerens (O. F. Miiller), and the terebellid Amphitrite johnstoni Malmgren were tested against seven alternate hosts. Each gave maximum response to its own host. However, the population from Acrocnida responded as strongly to Leptosynapta as to its own host, while giving no responses at all to any of the other five.
Biometry of the Copepod Calanus Finmarchicus (Gunn.) in Stages V and VI
Authors: Barnes H. , Barnes Margaret
Published: May 2009

One hundred each of stage VI male and female and stage V Calanus finmarchicus were picked at random, and, by means of a projection microscope, measurements made on a number of segments in both metasome and urosome.

The stage VI female population was mixed containing 95% of a smallsized population and 5% of a larger size-group. The males constituted a single population.

At this time of the season the stage VI male and female metasomes are the same length, but there are differences in the sizes of the individual segments, the most striking of which is that of the head

The stage V animals in many of the measurements could be quite clearly separated into two size-groups of about 50% each and it is suggested that these are potential male and female populations. This separation at 50/50 has been noticed in numerous other collections of stage V, but it shouldbe emphasized that the differences are population differences in regard to those measurements considered.

Evidence is presented which shows that the state of the antennules after preservation in 5% neutral formalin is unlikely in stage V animals to be a reliable guide to their sex in the next stage.
Blood Perfusion of the Kidney of Lophius Piscatorius L.
Authors: Brull L. , Nizet E. , Verney E. B.
Published: May 2009

Lophius kidneys perfused with the heparinized blood (venous) of the fish secrete urine in which total non-protein nitrogen is concentrated, magnesium highly concentrated, and chloride only slightly so or not at all. Oxygenation of the blood, or lowering the temperature of the perfusate from c. 20° to c. 5° C. does not appear to influence secretion. The blood flow through the kidneys increases with the perfusion pressure, the increase often becoming disproportionately large. The urine flow, on the other hand, above a certain critical level is largely independent of changes in perfusion pressure.
Chlorocruoroporphyrin: a Simple Method of Preparation
Authors: Kennedy Gilbert Y.
Published: May 2009

Munro Fox (1926, Addendum, p. 219) described a method of preparation of chlorocruoroporphyrin from the blood of the marine polychaete worm Spirographis. This was based upon the very troublesome method of Nencki & Zaleski (1900), which is time-consuming and wasteful. Furthermore, Spirographis is not easily obtainable in this country. Lemberg & Parker (1952) started with protoporphyrin, and by careful oxidation with potassium permanganate in acetone obtained a solution which gaVe mixed crystals of chlorocruoroporphyrin and diformyldeuteroporphyrin esters. Purification was by fractional chromatography. The procedure to be described here is simple and rapid, and could easily be carried out in one day by a biologist requiring a small sample of the porphyrin. The two methods mentioned above would not come into this category.

This work was done at the Plymouth Laboratory, and I am very grateful to Mr T. R. Tozer of that laboratory for so kindly obtaining the animals for me and extracting the blood.

The polychaete worms Myxicola infundibulum, Sabella pavonina and Branchiomma vesiculosum are all readily obtained from the muddy shores of the Salcombe estuary, especially on the Salstone. Blood was taken directly from the vessels of about 100 assorted worms by syringe, and squirted as it was removed from the worms into a mixture of peroxide-free ether (3 parts) and ‘Analar’ glacial acetic acid (1 part). After all the blood had been added, the mixture was well shaken and allowed to stand in the ice-chest for 30 min. The acetic acid was then washed out with distilled water, the first few washings containing a little sodium acetate to avoid washing out of the pigment, and the remaining solution of chlorocruorohaematin dried roughly by filtering through ether-soaked paper into a distilling flask and evaporated to dryness. 100 ml. of a 50% solution of hydrazine hydrate in glacial acetic acid were then added, and the mixture heated on a water-bath at 90° C. for 10 min.
Sea Temperatures in Plymouth Sound
Authors: Cooper L. H. N.
Published: May 2009

Monthly mean sea-water temperatures in Plymouth Sound, prepared by the Plymouth City Meteorologist, are presented as data for ecological studies in
this laboratory. In the last 40 years there has been a rise in mean temperature of about 0·3°C.
Note on the Temperature Tolerances of some Intertidal animals in Relation to Environmental Temperatures and Geographical Distribution
Authors: Southward A. J.
Published: May 2009

In experiments on four species of barnacles and four species of top-shells, the barnacles were found to be more resistant to high or low temperatures than the top-shells. Among each group of animals the degree of tolerance was related to the geographical distribution of the species and their zonation on the shore. Thus most tolerance of high temperature was shown by species of southern distribution, especially by those occurring at the upper limit of the midlittoral zone, and most tolerance of low temperature by species of northern distribution. Least tolerance of high and low temperatures was shown by species found only in the infralittoral fringe or below low water.

Field measurements of the body temperatures of barnacles and limpets while exposed to the air were made with thermocouples. Under many weather conditions the body temperatures were higher than would be expected from local meteorological values of air temperature. This difference was due to retention of sea temperature by the animals and the rocks and to the heating effects of sunlight.

The results of the laboratory experiments and of the field measurements are discussed together in relation to weather and geographical distribution. It is clear that the temperatures experienced on the shore are well within the tolerance limits of most of the animals, and even exceptional extremes of temperature may have little direct influence on the distribution of adult intertidal animals. Evidence for a causal relation between temperature and distribution must be sought in non-lethal terms such as debilitating effects, or indirectly through competition between species, or in combination with other factors.
The Adhesive Mechanisms of Monogenetic Trematodes: the Attachment of Species of the Diclidophoridae to the Gills of Gadoid Fishes
Authors: Llewellyn J.
Published: May 2009

An investigation of the adhesive mechanisms in all nine species of the genusDiclidophorahas shown that there is a common structure consisting of a pair of hinged jaws operated by intrinsic muscles and also by a more powerful extrinsic muscle which acts on a diaphragm to produce a suction pressure that is converted into a clamping action. This investigation has revealed errors in Cerfontaine's and other descriptions of the anatomy ofDiclidophoraadhesive organs, but substantiates Cerfontaine account of the adhesive mechanism, and therefore disagrees completely with the more recent account given by Sproston.
Eudactylina Rachelae N.Sp., a Copepod Parasitic on the Electric Ray, Torpedo Nobiliana Bonaparte
Authors: Green J.
Published: May 2009

Eudactylina rachelae n.sp. is described and figured. This copepod was found among the gill filaments of Torpedo nobiliana Bonaparte caught off Plymouth in July 1957.
Nematodes Parasitic on Sea Weeds of the Genera Ascophyllum and Fucus
Authors: Coles John W.
Published: May 2009

The nematode Halenchus fucicola (de Man), causing galls on the thallus of the sea weed yAscophyllum nodosum, has been found in the Plymouth area (Wembury Bay) and at Croyde Bay on the north Devon coast, and a redescription of the worm is given. A new species of Halenchus (H. dumnonicus) causing similar growths on the sea weeds Fucus vesiculosus and F. serratus is described. This latter form is also found at Wembury Bay; at Looe, Cornwall, and at Lyme Regis, Dorset.
The Distribution of Intertidal Organisms Along the Coasts of the English Channel
Authors: Crisp D. J. , Southward A. J.
Published: May 2009

The English Channel may conveniently be divided into a western basin and an eastern basin separated by a line drawn approximately between the Cherbourg peninsula and the Isle of Wight. In these basins, the environmental factors are very different. Thus the water of the western basin is on average warmer and slightly more saline than that of the eastern basin and its temperature variation is less extreme. The French side of the Channel is warmer than the English coast only in the western basin. The tidal oscillations in the two basins are out of phase with each other and the strongest tidal currents occur where the two basins join. The main residual flow is up-Channel with minor coastal eddies.

The shores at the western end of the Channel are generally rocky, they are close to deep water, and so are exposed to frequent heavy swells. The shores of the eastern basin are generally erodible, and accumulations of sand and shingle tend to reduce the force of the waves. The water of the eastern basin generally contains more suspended matter and the shores are usually scoured by sand and shingle.

The distribution of the following animals is given in some detail and compared with earlier records:Ammonia sulcata, Actinia equina, Chthamalus stellatus, Balanus balanoides, B. perforatus, B. crenatus, B. improvisus, Elminius modestus, Verruca stroemia, Hemioniscus balani, Patella vulgata, P. depressa, P. aspera, Monodonta lineata, Gibbula umbilicalis, G. pennanti, G. cineraria, Littorina saxatilis, L. littoralis, L. littorea, L. neritoides, Paracentrotus lividus. The distribution of certain other species is also discussed:Balanus balanus, Haliotis tuberculata, Gibbula magusandCalliostoma zizyphinum.
Studies on Marine Flagellates IV. Morphology and Microanatomy of a new Species of Chrysochromulina
Authors: Parke Mary , Manton Irene , Clarke B.
Published: May 2009

The description of a new species of the genus Chrysochromulina, C. chiton, includes for the first time some evidence from the electron microscopy of sections in addition to the techniques previously used. Important diagnostic characters are the exceptionally large scales, which are shown to be of two kinds, the larger being saucer-shaped, and the smaller plate-like with a narrow rim flexed towards the upper surface; the structure and arrangement of the two types of scale on the body are described. Anatomical facts are given for the first time for the internal structure of the haptonema; in this species this organ consists of three concentric membranes surrounding a ring of seven fibres or tubes, the centre of the haptonema being hollow; this combination of characters distinguishes the organ fundamentally from a flagellum. Microanatomical facts are also given for the following major cell organs: the nucleus, the chromatophores including the pyrenoids, mitochondria, putative golgi material, muciferous bodies, the flagellar bases (preliminary observations only). Other distinguishable cytoplasmic components include the surface membrane, unsaturated fat bodies, vesicles of various kinds and granular protoplasm in the interstices.
An Experimental Analysis of the Behaviour ofLittorina Littorea(L.) Under Natural Conditions and in the Laboratory
Authors: Newell G. E.
Published: May 2009

Winkles dwelling on horizontal surfaces orientate by means of a lightcompass reaction. As the tide recedes, most of the tracks in the sand are towards the sun but after a time each animal reverses its direction of crawling, so tracing out a roughly U-shaped path which leads it back, approximately, to its starting-point.

When kept in an aquarium winkles tend to settle on the sides above the waterline and to become inactive. When stimulated, as by immersion, they crawl downwards, then horizontally and then upwards before settling above the waterline.

Winkles collected from horizontal surfaces at first show no tendency to climb vertical surfaces in an aquarium. After a period which varies from a few hours up to 10 days they do climb the sides of the tank. Animals collected from vertical surfaces climb the sides of the aquarium at their first opportunity and then settle. It can be concluded that winkles have an inherent tendency to climb and settle in the head-up position on vertical or steeply sloping surfaces but that if this opportunity is denied them they become habituated to horizontal surfaces.

The minimum angle to which winkles can react by gravitational responses is of the order of 10–20 degrees.

In an aquarium starved winkles prolong their excursions below water when presented with suitable food but fully fed animals respond less strongly to the stimulus of immersion.

Dark-adapted winkles from horizontal surfaces are at first positively phototactic, but after a time varying from 15 to 20 min, they become negatively phototactic. Tested with the ‘two-light’ experiment most animals disregard the second light (telotaxis).
A Comparative Study of the Reproductive Cycles of the Cockles Cerastoderma Edule and C. Glaucum
Authors: Boyden C. R.
Published: May 2009

The reproductive cycles of the two cockles Cerastoderma edule (L.) and C.glaucum (Poiret) (= Cardium lamarcki Reeve) from a mixed population in the Crouch estuary, Essex, have been investigated. Reproductive maturity was estimated by assessment of gonad condition. A difference in maturity related to shore level was noted. The reproductive cycles of the two cockles were found to be essentially similar. Rapid gametogenesis occurred in both cockles in spring, C. edule then spawned in May, whereas C. glaucum did not spawn until July. The difference in time of spawning appears to be responsible for the maintenance of the two genotypes in a sympatric association, as hybridization experiments showed an absence of isolation at the gamete level. The relationship between C. edule and C. glaucum is discussed.
On the Postlarva of the Goby Lebetus
Authors: Neclâ Demir  , Russell F. S.
Published: May 2009

An examination of the postlarvae of the goby Lebetus Winther collected in the neighbourhood of Plymouth shows that there are two forms, separable on degree of development of the fins, meristic characters and body proportions. The differences are sufficient to indicate that there must be two species whose identity can only be made certain by rearing, since the original two species L. orca (Collett) and L. scorpioides (Collett) have recently been regarded as one species showing sexual dimorphism.
The Distribution and Abundance of Larval Sand-Eels [Ammodytidae] in Scottish Waters
Authors: Langham N. P. E.
Published: May 2009

The distribution of the larvae of four of the five species of Ammodytidae occurring in Scottish waters is examined. The two most abundant species, Ammodytes marinus Raitt and Gymnammodytes semisquamatus (Jourdain) are described in detail and their abundance recorded. A. marinus larvae were found throughout the survey area, but were most abundant in the Moray Firth and around Orkney. G. semisquamatus larvae were most abundant along the north and west coasts, although they were recorded in a few areas off the east coast of Scotland. A. lanceolatus Lesauvage larvae occurred generally in Scottish waters, although few larvae were caught. A. immaculatus Corbin larvae, which have not previously been recorded in the Scottish area, were also rare and were restricted to areas off the north and west coasts. The material was not suitable for demonstrating the distribution of larvae of A. lancea Raitt. The occurrence of larvae is related to the spawning season of each species.
Some Effects of Salinity on the Mysid Praunus Flexuosus
Authors: Mclusky D. S. , Heard V. E. J.
Published: May 2009

The population dynamics of the mysid crustacean Praunus flexuosus have been studied at Ardmaddy Bay, Loch Etive. A salinity tolerance range of 2–33‰ has been demonstrated, over which the body tissues experience the range 11–28‰. Comparison is made between the osmoregulatory capacity of Praunus flexuosus and the closely related Neomysis integer.
Holkham Salts Hole, an Isolated Salt-Water pond with Relict Features. An Account Based on Studies by the late C. F. A. Pantin
Authors: Hunt O. D.
Published: May 2009

A saline pond known as the ‘Salts Hole’ at Holkham on the north coast of Norfolk is situated between the pine-covered sand-hills and the fields that have been reclaimed for agriculture from pre-existing salt-marshes. It has a salinity of about 75% of that of sea water and supports a peculiar relict marine fauna. Except for the rare occurrence of flooding for a short period, as in the great storm of 1953, the pond has probably been cut off from the sea for about 250 years. It presents three problems: how it got its fauna and flora; how its marine character is maintained; and how the pond originated geographically. The fauna and flora, as described, show the pond as a refuge where various marine and brackish species have managed to maintain themselves and co-exist in water outside their normal and differing ranges of salinity. The main character of the pond is kept remarkably constant with respect to salinity, alkalinity, temperature and oxygenation. The pond is a study in ‘natural engineering’, constituting a natural marine aquarium with natural controls. It is fed near the level of high-water neap tide by continuous flow from a salt spring of very constant salinity supplied from water contained in the extensive coastal sands. Its only apparent artificial feature is the outlet controlled by a dam through a culvert into a ditch that conveys its water through the fields to the sea at Wells nearly two miles away. Search in the muniment room at Holkham Hall brought to light maps dating back to Elizabethan days which show the history of the Salts Hole.
Orientation and Migration in the Sea
Authors: Williamson R.
Published: May 2009

INTRODUCTION

Orientation is crucial for almost all organisms, from bacteria to mammals, for selecting habitat or feeding grounds, deciding up from down, or just keeping track of your position, or your neighbour's. The marine environment is an especially rich source of material, particularly for the study of migration, where many animals cover enormous distances, and appear do this with reference to very few sensory cues. The mechanisms underlying these processes, and the benefits they bring to the organism, are only now beginning to be understood.
The Kinematical Principles Governing Horizontal Transport Induced by Vertical Migration in Tidal Flows
Authors: Hill A.E.
Published: May 2009

Vertical migration interacts with oscillatory tidal flows to produce horizontal transport. When the vertical migration period is an exact multiple of the tidal period then net uni-directional horizontal transport can occur. This happens most effectively in ‘selective tidal-stream transport’ for which vertical migration into the flow is specifically synchronized with the dominant (usually M2) tidal constituent. When migration and tide are not synchronized there is no net transport and, instead, a horizontal displacement oscillation of the organism takes place at the beat period between the vertical migration and tidal periods. The most common form of vertical migration is synchronized, not with the tide, but with the day-night cycle. Diel migration in M2-period tidal currents induces no net transport, but can produce excursions of several tens of kilometres over just a few days. Diel vertical migration can, however, interact with the sun-generated part of the semi-diurnal tide to produce net horizontal transport, the direction of which is controlled by the phase of the S2 tidal currents. The spatial distribution of phase implies that regions of horizontal convergence and divergence will result from diel migration. Diel migration in diurnal-period tides causes the preferred direction of transport to reverse at six-monthly intervals.
The Propulsion Jet ofEuphausia Superba(Antarctic Krill) as a Potential Communication Signal among Conspecifics
Authors: Wiese K. , Ebina Y.
Published: May 2009

INTRODUCTION

Individuals of the Antarctic krillEuphausia superbaDana assemble in spring into dense formations (estimated 20,000 m3) which swim for long distances and at considerable speed (estimated 20 cm s−1) to search for patches of phytoplankton (Hamner, 1984). Recruitment to schools and maintenance of a defined position in a travelling formation, a remarkable social behaviour, requires some kind of communication system between individuals.

Vision, as a sophisticated image-processing system, habituating strongly with time, appears inappropriate for the task of continuously monitoring position in the formation. This is not in contradiction of the fact that the prominent eyes ofEuphausiaorient the shrimp with respect to the axis of light coming from above, and direct the photophores 180° away from light (Land, 1980). The function of the photophores is only partially explained (e.g. predator avoidance by counter-shading, Grinnell et al., 1988), their role in formation swimming being doubtful because they are reportedly active only during dawn and dusk. Of course the eyes helpEuphausiato assemble in schools and to evade predators (Strand & Hamner, 1990) as well as fishing nets (Everson & Bone, 1986a,b), but a simple mechanical reflex seems more suitable to control individual position in the formation.
The Orientation of Tail-Flip Escape Swimming in Decapod and Mysid Crustaceans
Authors: Neil Douglas M. , Ansell Alan D.
Published: May 2009

The orientation of tail-flip escape swimming in a range of adult decapod and mysid crustaceans is reviewed. In mechanical terms, tail-flip swimming constitutes unsteady locomotion in which a single ‘appendage’, the abdomen, produces thrust by a combination of a rowing action and a final ‘squeeze’ force when the abdomen presses against the cephalothorax. In small crustaceans, a symmetrical ‘jack-knife’ tail-flip is more typical. Tail-flip flexion is controlled by two giant-fibre pathways, and also by a non-giant-neuronal network. The direction of thrust in the sagittal plane, and hence the elevation, translation and rotation of the tail-flip are dependent upon the point of stimulation and on the giant-fibre pathway activated. The laterality of the stimulus also affects the orientation of swimming, which is directed away from the point of stimulation. In large decapods such as the lobstersNephrops norvegicusandJasus lalandiisteering is produced by asym-metrical movements of various abdominal appendages, and by rotation of the abdomen about the cephalothorax. In slipper lobsters the flattened antennae provide steering surfaces. In smaller decapods, such as the brown shrimpCrangon crangon, and in mysids, such asPraunus flexuosus, steering is effected by a rapid rotation of the whole body about its longitudinal axis during the initial stages of tail-flip flexion. The effectiveness of tail-flip swimming is considered in the context of predator-prey interactions under natural conditions and in relation to artificial threats from fishing gear.
Movement of Sole (Solea Solea) in the Bay of Biscay: Coastal Environment and Spawning Migration
Authors: Koutsikopoulos Constantin , Dorel Didier , Desaunay Yves
Published: May 2009

During the studies on sole recruitment in the Bay of Biscay, transport process attracted considerable attention and led to important research on migration and dispersal. The last step to complete the study of the spatial component of the life cycle of sole in the northern part of the Bay of Biscay is the offshore migration of young adults towards the spawning grounds. the present study deals with this pre-spawning migration. the main question concerns the kind of linkage between nurseries and spawning grounds. The principal results are based on extensive tagging experiments carried out in autumn 1992 in two distinct nursery grounds, Bay of Vilaine and Pertuis (4620 soles of 2-group and older). One year later (January 1994) catches of tagged individuals reached 18.1% and 11.9% of the initial samples, respectively. From September to February a 50-km net displacement of the centre of the population was observed towards the offshore deeper area. A small trend to move onshore appeared in spring. In parallel with these net movements individuals were dispersed around the centre of gravity of the population. This dispersion was higher in a direction parallel to the coast. Individuals from different nurseries were mixed over the same spawning areas of the Bay of Biscay, and some individuals were also captured in and close to the English Channel. Changes in distribution were in phase with environmental changes and some elements concerning topographic preferences also appeared. Some evidence for orientation was observed but random dispersal seemed more important. No particular link between a given nursery and a spawning ground in the vicinity appeared.
Homing Ability and Home Range of Yellow-Phase American Eels in a Tidally Dominated Estuary
Authors: Parker S.J.
Published: May 2009

Yellow-phase American eels,Anguilla rostrata, were displaced 10–17 km between tidal fresh water and salinity-stratified water and followed to determine the degree of home site fidelity, swiftness of homing and whether environmental factors affect orientation or homing behaviour. Twenty-one eels were tracked continuously (eight eels displaced up the estuary, eight down the estuary and five controls) in the Penobscot Estuary, Maine, USA for 4–80 h each, while recording position every 20 min. Nine of the 16 displaced eels (56%) returned to their capture site either during the track or shortly afterwards. Three of the remaining seven eels made substantial progress towards their capture site within the time observed. Eels homed with equal frequency whether displaced up or down the estuary in an average of 220 h ±87 (SE). After release, no eel moved farther away from its capture site. The eels were active mostly at night but used only the appropriate tidal currents rather than directed swimming to move about their home range and to home. Control tracks provided a home-range estimate in this habitat of 6.7 ±1.6 km of estuary or 325 ±64 ha. Lunar phase or position of the moon did not appear to influence either homing behaviour or activity patterns. This study shows that orientation and homing to a specific site in eels occurs relatively quickly and with no initial errors in orientation.
Evidence ForDe NovoBiosynthesis of Coelenterazine in the Bioluminescent Midwater Shrimp,Systellaspis DebilisC
Authors: Thomson Catherine M. , Herring Peter J. , Campbell Anthony K.
Published: May 2009

Coelenterazine chemiluminescence is now established as the most common chemistry responsible for bioluminescence in the sea, being found in seven phyla. However, the organisms which synthesize coelenterazine have yet to be identified. In order to deter-mine whether the luminous midwater shrimpSystellaspis debilis(A. Milne Edwards) (Arthropoda: Decapoda) is capable of luciferin biosynthesis, a developmental series of eggs was assayed for its luciferin, coelenterazine. The advantages of this system are thatS. debiliseggs are autonomous and therefore have no external nutrient supply, the embryos can be ranked for developmental stage and the large egg size allows clutch numbers to be determined accurately. Recombinant apo-aequorin, which requires coelenterazine for luminescence, was used to quantify coelenterazine during the developmental sequence. An increase of almost two orders of magnitude was detected in coelenterazine content per egg between the first and final stage of development (mean values of 1 pmol and 71 pmol). This demonstratesde novobiosynthesis of coelenterazine for the first time.
Deep-Water Mysids of the Catalan Sea: Species Composition, Bathymetric and Near-Bottom Distribution
Authors: Cartes J.E. , Sorbe J.C.
Published: May 2009

Deep-water suprabenthic species of Mysidacea were studied in the Catalan Sea (western Mediterranean). Twenty-one samples were taken at depths from 385 to 1859 m, using a Macer-Giroq type sledge. Sixteen mysid species have been collected.Boreomysis arcticawas the commonest species andParapseudomma calloplura, Paramblyops rostrataandErythrops neapolitanawere also notable for their high occurrence. The genusDactylamblyops, Mysidella biscayensisandPseudomma affinewere recorded for the first time in the Mediterranean. The greatest total abundance of mysids was found over the middle slope. On the upper slopeP. callopluraandE. neapolitanaformed the dominant species, and deeperB. arcticadominated. Species richness and diversity (H’) declined with increasing depth. The decrease in H’ was attributable to the growing dominance ofB. arcticaover the middle and lower slopes. Swimming coefficients near the bottom showed intraspecific differences. In general, the species collected inhabit the water column between 0.1 and 0.5 m above the bottom. The bathypelagic speciesEucopia hansenihad high swimming coefficients. Amongst the suprabenthic species,B. arcticashowed the highest swimming coefficients, and rose from the near-bottom during night on the upper and middle slope stations.