bluuebunny/crossref_metadata_2025_split huggingface dataset:
On seahorse locomotion
Authors: Blake R. W. 
Published: May 2009

There are few teleosts which depart from the ‘classical’ ichthyan body form to such an extent as the seahorse,Hippocampus. In this genus the caudal fin is absent and the tail has become prehensile, the usual function of the caudal fin is taken over by the dorsal and pectoral fins. The dorsal and pectoral fins both have a sculling action, the small anal fin moves ‘bodily’ through the water from side to side.In the past, interest has generally centred on fast moving fish, which have evolved a limited number of body forms, as few variations are possible without a sacrifice of speed. The evolution of the swimming mechanisms of these fish has favoured an increase in the maximum speed and acceleration. In relinquishing the demands of speed the seahorse has released itself from restrictions which would limit its possible range of form.
A Diver-Monitored Dredge for Sampling Motile Epibenthos
Authors: Kritzler Henry , Eidemiller Anne 
Published: May 2009

A dredge equipped with a gate which may be opened by a diver-monitor when it is passing over bottom selected for study and closed elsewhere is described. A meter wheel which activates an electric switch, connected with a battery and counter in the boat, is in contact with the bottom when the gate is open and raised from the bottom when it is closed. This permits the taking of sampling units of uniform predetermined size. Field trials demonstrated that the dredge efficiently captured all categories of animals large enough to be retained by its meshes.The difficulty of obtaining unbiased, representative samples of single populations is compounded by the complexities of aggregates of populations, such as biotic communities, and even more by discontinuities in the dispersion of the constituent species and the habitats in which they live. The probability of taking such unbiased, representative samples of marine communities decreases with the depth of water from which they are obtained. Sampling confidence at a level which may be taken for granted in terrestrial habitats is possible only in the littoral and shallow sublittoral. And this is true only if the investigator is able to assure himself that each sampling unit is excised only from the kind of habitat whose biota he wishes to study. He may achieve this specificity in sampling benthos, for example, by using grabs and discarding material brought up from bottom types not under investigation. Another approach is to engage in a comprehensive, preliminary, systematic exploration so that when he samples for parametric estimates he can place his grab exactly where he knows that the desired habitat exists.
The Significance of Squid, Whale and Other Remains From the Stomachs of Bottom-Living Deep-Sea Fish
Authors: Clarke Malcolm R. , Merrett Nigel 
Published: May 2009

Twenty-four out of 240 fishes caught by bottom lines at 366–3333 m had something in their stomachs. Stomach contents included parts of cephalopods, fish, cetaceans and bottom-living invertebrates, thin rubber sheet and terrestrial mammal bones. The material provides evidence that four species of cephalopod are at least partially demersal and suggests a means by which the tapeworm Phyllobothrium could pass from its secondary to its primary host.During the five biological cruises of R.R.S. ‘Discovery’ between 1967 and 1971 a total of 31 bottom lines with 1483 hooks were fished in depths of water between 366 and 3333 m. The stomachs of the 240 fish caught were examined and 216 (90%) proved to be empty. The high incidence of empty stomachs is thought to be due to frequent loss of food during the ascent from great depths and accounts for our poor knowledge of the feeding habits of demersal fish living at depths exceeding 400 m.The present collection of food from 25 stomachs (24 from ‘Discovery’ collections and one from a fish caught by Mr G. R. Forster from R. V. ‘Sarsia’) of fish belonging to 11 species (Table 1) probably gives little indication of the usual diet of the fish concerned, but its nature prompts some useful speculation and the rarity of such observations justifies placing them on record (Bigelow & Schroeder, 1948; Marshall, 1954).All the fish were caught on lines which lay on the bottom for several hours and it is our firm belief that they were hooked while on or very near the bottom.
Some Aspects of the Biology of the Sandeel,Ammodytes TobianusL., in Langstone Harbour, Hampshire
Authors: Reay P. J. 
Published: May 2009

This paper is concerned with the biology of the sandeel,Ammodytes tobianusL., in Langstone Harbour, Hampshire; this was the main area studied in a survey of sandeel populations which are exploited for bait along the south coast of England. Aspects considered are the relative occurrence of the spawning groups; spawning seasons; population structure in terms of length, sex, age and maturity; mortality; annual growth; seasonal growth; and condition. The seasonal pattern of otolith growth and its application to the back-calculation technique, has been described elsewhere (Reay, 1972).A. tobianusforms over 95% of the total sandeel catch in Langstone Harbour.Hyperoplus lanceolatus(Le Sauvage) is the only other species to occur regularly, but individuals of the three other British species,A. marinusRaitt,H. immaculatus(Corbin), andGymnammodytes semisquamatus(Jourdain), have also been recorded. This pattern of species composition is also found in the other inshore areas studied along the south coast.
A Specialized Predator-Prey Relationship Between the Copepod Sapphirina Angusta and the Pelagic Tunicate Thalia Democratica
Authors: Heron A. C. 
Published: May 2009

It is usually very difficult to obtain knowledge of predator-prey relationships in the marine plankton. However, because of the very specialized nature of this relationship, where the copepod spends part of its life as a parasite and part of its life as a predator, detailed understanding of the relationship has been obtained from both laboratory and field observations.The usual concept of predation involves a predator which is the same size or larger than its prey. This prompted Foxton (1966), in discussion of the large salp Salpa thompsoni, to consider only the gut contents offish, sea birds, seals, etc., when analysing data on predation. He noted that considerable mortality occurred between the embryos and the adult stages which did not appear to be explained by the data on predators which he considered. He concluded that ‘further study is necessary before (the salp's) true role can be defined’.Copepods and amphipods are often associated with salps in distribution (Hardy, 1936), usually being regarded as parasites (Furuhashi, 1966; Wolfenden, 1911). Amphipods which lay their eggs directly into the living tissue of salps have been described (Haruhiko, 1967), while the use of the salp test as a protective house by the amphipod Phronema is well known (Hardy, 1956).Dense swarms of Thalia democratica occurring in S.E. Australian waters are often associated with high densities of Sapphirina copepods (Dakin & Colefax, 1940; Thompson, 1948; Sheard, 1965). Observations of these swarms underwater, by the author, show the presence of many Sapphirina copepods inside salps in the undisturbed state, as in Plate I (A).
Feeding, Growth, Reproduction and Nitrogen Utilization by the Harpacticoid Copepod,Tigriopus Brevicornis
Authors: Harris R. P. 
Published: May 2009

Growth of the littoral harpacticoid copepodTigriopus brevicornisO. F. Müller was measured in an intertidal rock pool. The generation time at the field temperature of 15°C was 31 days, and growth during this period resulted in an increase of 1.1829 μg body nitrogen.Measurements of nitrogen excreted by developmental stages were made on animals removed from the natural population. Ammonia comprised on average 89.7% of the total nitrogen excreted by adults. Some measurements of phosphorus excretion indicated a nitrogen: phosphorus ratio in excretory products of 4.86. Adult females excreted 27.2 μg N/mg dry wt/day, representing a release of about 30% of body nitrogen daily. Excretory rates of earlier copepodite and naupliar stages were higher.The efficiency with which ingested food was assimilated was measured for animals feeding on natural suspended matter obtained from the pool. Assimilation efficiencies averaged 75.4%.Egg production was measured at a range of temperatures in the laboratory, enabling an estimate to be made of total production by an individual female. At 15°C females produced an average of ten egg sacs in 30 days.Measurement of nitrogen lost during moulting suggested a value of 6% of total body nitrogen.The data obtained have been used to estimate growth efficiency in terms of nitrogen during the entire life-history of a female in the pool. Gross growth efficiency calculated for the period of growth from egg to adult is 13.0% and the net efficiency 17.2%. Efficiencies of egg production by the adult female are higher, the gross efficiency being 22.1% and the net 29.3%. During the entire life-span 72.9% of assimilated nitrogen is expended in metabolism, 3.9% in growth, 0.4% as moults, and 26.6% in egg production.
An Experimental Assessment of the Status of the Species Enteromorpha Intestinalis (L.) Link and Enteromorpha Compressa (L.) Grev.
Authors: De Silva M. W. R. N. , Burrows Elsie M. 
Published: May 2009

Many workers have experienced difficulties in trying to identify species within the genus Enteromorpha. The difficulties arise from our lack of knowledge of the range of variation for the characters used to delimit the taxa and of the sources of the variation shown.Enteromorpha intestinalis (L.) Link was originally described by Linnaeus (1753) under the name Ulva intestinalis as ‘Ulva tubulosa simplex’ and Enteromorpha compressa (L.) Grev., also by Linnaeus (1753) under the name Ulva compressa as ‘Ulva tubulosa ramosa compressa’. In their interpretations by later authors, the two species differ only in that the former is unbranched and the latter branched. In their cell size, in the unordered arrangement of the cells and in the single pyrenoid in the chloroplast, they seem to belong together. Whether or not a plant is branched would seem to be a straightforward character to use in practice, but for an alga of this kind this is not necessarily so. In its development the unbranched tube of the thallus begins life as a zoospore or zygote which at first divides transversely to form a short uniseriate filament and later by radial longitudinal divisions, the subsequent expansion of which leads to the formation of the hollow tube. In the formation of branches, individual cells, usually towards the base of the frond, divide by a single periclinal division. The outer cell of the pair thus formed then divides transversely forming a single-celled filament, later dividing by radial longitudinal divisions and repeating the structure of the main axis.
The Vitamin B12Requirement Of The Marine RotiferBrachionus Plicatilis
Authors: Scott J. M. 
Published: May 2009

The nutrient requirements of many algae are well documented, with most algae being found to need only one or two vitamins. In the case of their predators, only a handful of microinvertebrates have had their diets and even fewer their vitamin requirements denned. Thus, any progress in this field together with the mode of nutrient uptake, must lead to a better understanding of the component-transfer in the food chain.Brachionus plicatilisMüller has been reported to require vitamin B12(Droop & Scott, 1978). The work described in this paper sought first, to confirm this and then to establish the mode of uptake. The algaBrachiomonas submarinavar.pulsiferaDroop was used to investigate the first of these questions as the writer had previous experience with it in steady-state energetics work. The algaDunaliellaSMBA Strain 246 was used to examine the mode of uptake by the rotifer since this had also been found to be a good food organism. The possibilities considered were uptake: (a) via the algal cell; (b) directly from solution; (c) a combination of both. Mode of vitamin B12uptake is of particular interest as it may be representative of the pathway of many of the rotifer's water soluble micronutrients.Before considering the influence of the vitamin onBrachionusinvestigations were made into the relationship between the vitamin and the two food-algae. It has already been established thatBrachiomonashas a definite requirement (Droop, 1961) andDunaliellano requirement for vitamin B12(Turner, 1979). It was of interest to see if they took-up the vitamin in the manner shown byMonochrysts, a B12requirer, andPhaeodactyluma non-requirer (Droop, 1968).
Certain Effects of Agitation Upon the Release of Phosphate from Mud
Authors: Stephenson William 
Published: May 2009

When sea water is stirred with mud and then filtered, its phosphate concentration may either increase or decrease. When the filtrate is ultrafiltered, the concentration increases.Similar increases occur when the filtrate is stored in glassware, and these obscure any effects of the presence of colloidal material. On storage concentrations rise for about 2 hr., and then fall to as low as 2 mg./m.3 P2O5 in 18 hr.Rise and fall are both prevented by the addition of formalin, chloroform or toluene, and are more noticeable in small containing vessels. Both occur during either day or night, and when temperatures are either rising or falling.
British Folliculinidae (Ciliata, Heterotricha)
Authors: Das S. M. 
Published: May 2009

A brief résumé is given of the work done on British Folliculinidae up to the present time.Descriptions follow of eight British species, many of which are revised accounts based on personal observations.A new species, Folliculinopsis elongata, is described.A revised key for the identification of British Folliculinidae is given.
The Structure and Mode of Life of the Pyramidellidae, Parasitic Opisthobranchs
Authors: Fretter V. , Graham A. 
Published: May 2009

The family Pyramidellidae contains a number of species of gastropod molluscs of similar structure and mode of life.The shell is calcareous and spirally wound and may be closed by an operculum. The foot bears a transverse fold anteriorly, the mentum (Fig. 1, MT), separating the opening of the penial sheath (PO) below from the mouth (M) above. It has a lateral glandular streak on each side (Fig. 2), presumably sensory.The head has ear-shaped tentacles (Fig. 1, T), richly innervated and with cilia setting up a strong water current, so that they constitute a powerful sensory mechanism. The eyes (E) lie between the tentacles.
Observations on the Absorption of Radioactive Strontium and Yttrium by Marine Algae
Authors: Spooner G. M. 
Published: May 2009

Certain marine algae were treated with sea water containing carrier-free radioactive strontium (mixture of Sr89 and Sr90), to test whether these ions were taken up by the weeds.At the same time the behaviour of radioactive yttrium (Y90), which occurred as a short-lived daughter-product of Sr90, was investigated by the expedient of studying the ‘decay’ characteristics of specimens of water and weed.Promising possibilities of this technique, by which an isotope is made available for study by applying its parent substance, are pointed out.Radioactive strontium is extracted from sea water by the brown sea-weeds, in particular by Fucus serratus.It is held that this effect is simply a result of ionic exchange, and that the algae regularly contain many times as much strontium in their cell fluids as exists in sea water.
On the Volume Measurement of Water Filtered by a Plankton Pump, with Some Observations on the Distribution of Planktonic Animals
Authors: Barnes H. 
Published: May 2009

The accuracy of volume estimation in filling a marked tank by means of a plankton pump has been determined. The method even in its simplest form is satisfactory under good conditions. Further refinements, in which the plankton was filtered off, after filling a modified tank (for example with an overflow device) would no doubt increase the accuracy.A device is described by which, using an ex-N.F.S. pump, a constant (but variable by selection) volume of water can be taken without the use of large tanks.A small number of sets of samples taken with adequate volume control indicate the same order of variability as net hauls. Comparison of the distribution of x2 for paired samples with nets and pumps also indicates variation of a similar type.These results suggest that the variability of net hauls is not entirely due to the variations in the volume of water filtered. Further work is in hand to elucidate this question.
An Apparatus for Producing Artificial Tides
Authors: Aleem Anwar Abdel 
Published: May 2009

It is often desired to grow animals and plants of the intertidal zone in the laboratory, under conditions as far as possible simulating those in nature and with the least trouble and expense. This need was felt by the writer during an ecological study of the diatoms inhabiting the mud-flats at Whitstable, Kent. It was found necessary to maintain such diatoms in the laboratory in London in a healthy condition for several days so as to study the effect of light and tides on their movements. The apparatus described in this paper was therefore devised. It has an advantage over other tidal systems (Bracher, 1919; Martin & Reid, 1935) in that the substratum could be automatically alternately flooded and drained at regular intervals by a much simpler mechanism. Besides, it is more handy and can be operated with only a small supply of sea water, a matter of some importance in localities remote from the sea.It consists of a tidal chamber, T, and a reservoir, R (Fig. I). The former is an inverted bell-jar fitted with a rubber bung through which passes a long glass tube, g, which extends to the base of the reservoir. At the upper end of the tube is a small funnel by which sea water enters the apparatus. A ⋯tube, t, serves to connect the tidal chamber and reservoir, its horizontal arm being connected to the siphon S.The wide-mouthed bottle constituting the reservoir is fitted with a stopcock, v, which is useful for expelling air when setting up the apparatus.
Cascading Over the Continental Slope of Water from the Celtic Sea
Authors: Cooper L. H. N. , Vaux David 
Published: May 2009

In the Celtic Sea, to the south of Ireland, water in some winters becomes sufficiently cooled and heavy to flow to the edge of the continental shelf and to run down the continental slope to a depth of several hundred metres. A theory of the phenomenon, termed ‘cascading’, has been developed. Three winters have been examined in detail.In February 1927 much water, heavy enough to cascade, was present in the Celtic Sea and also in the English Channel. A probable course and speed of the cascading water over the shelf has been established. Since there were few observations of salinity and temperature over or beyond the slope, and none of oxygen anywhere, the theory cannot be completely established on the basis of the 1927 observations, full though they were.
Biological Differences Between Sea Waters: Experiments in 1954 and 1955
Authors: Wilson Douglas P. , Armstrong F. A. J. 
Published: May 2009

In 1954 and 1955 various natural, artificial and treated sea waters were tested with developing eggs of Echinus esculentus. The following are the main observations:1. Sea waters filtered through Doulton candles at the time of collection and proved bacteriologically sterile until use were very little different from sea waters collected at the same time in the ordinary way and not sterile. (Expts. 1, 3, 8 and, with qualifications, 6.)2. Undiluted Celtic sea bottom water and undiluted Celtic mud ‘extract’ were harmful to the eggs, but small volumes of both added to natural sea waters and to artificial sea water had a stimulating effect. (Expt. 1.)3. In water from near the bottom at E1 eggs did worse, in 1954, than in surface water from the same locality. In 1955 they did slightly better in the deeper water. (Expts. 3, 4 and 7.)4. Eggs placed immediately after fertilization in water from near the bottom at E1 (and from near the bottom at the Echinus ground) and transferred at first cleavage to surface waters were affected unfavourably. (Expts. 3, 4 and 7.) Artificial sea water had no such effect. (Expt. 5.)5. The addition to natural and to artificial sea waters of filtrates from culture medium (‘erdschreiber’) and from thick cultures of diatoms and flagellates had no significant effects on the eggs developing in those waters. (Expt. 6.)6. In 1955 surface water from the Clyde was a better medium for development than surface water from E1. The difference was similar to that frequently observed several years previously. (Expt. 7.)7. Extracts of natural sea waters made by a new process were non-poisonous, but the experiment in which they were added to artificial sea water was inconclusive owing to the eggs proving to be of poor quality. (Expt. 8.)
Some Observations onEvadne NordmanniLovén
Authors: Bainbridge V. 
Published: May 2009

During 1951Evadne nordmanniwas present in the Clyde plankton from late February to the end of October and was most abundant during May and early June. The bulk of the population was always found in the top 30 m. Reproduction is mainly parthenogenetic; sexual individuals first appeared in May and sexual reproduction was most intense during October.The relation between maternal size and stage of embryonic development is described. Sexual females showing the formation of a resting egg are large and have previously produced at least one brood by parthenogenesis.Of the females with embryos at an early stage of development the primiparae have smaller broods than larger and older individuals. During the development of embryos some may be resorbed and in the primiparae this results in a decrease of embryo number with increase of size. Larger individuals tend to produce larger broods of young.There was a considerable decrease of size from June to July and a partial recovery in August. These fluctuations follow similar fluctuations in embryo production.The reproductive capacity of the parthenogenetic females and the intensity of sexual reproduction did not show any clear relationship, though there are indications that the latter is favoured by moderate rather than severe depression.Food organisms are captured only during the hours of daylight.Evadneappears to be a selective feeder the diet of which consists mainly of tintinnids and peridinians.Several aspects of the biology of the species are discussed with reference to the findings on the food and feeding habits.
Further Observations on Proprioceptors in Crustacea and a Hypothesis About Their Function
Authors: Alexandrowicz J. S. 
Published: May 2009

In the coxal region ofEupagurus bernardusthe following receptor organs have been found: (1) a muscular receptor spanning the thoracico-coxal articulation, its innervation, in which several neurons take part, being arranged on a similar pattern as inCarcinus; (2) two innervated elastic strands running along the bundles of mm. levator and depressor basipoditis respectively and inserting into the tendons of these muscles; (3) a coxo-basipodite receptor consisting of connective tissue strand with numerous bipolar nerve cells ending on it. With the exception of the coxo-basipodite receptor, all sensory neurons of these organs have their cell bodies located in the central nervous system.It is suggested that these receptors convey impulses elicited by the movements of the legs and some hypotheses concerning the role of each of them are put forward.