Among the teleosts three basic modes of locomotion have been recognized; anguilli-form, carangiform and ostraciiform (Breder, 1926). During the past 50 years much attention has been paid to the anguilliform (Breder, 1926; Gray, 1933 a, b; Gadd, 1952; Taylor, 1952; Lighthill, 1960, 1969, 1970) and carangiform (Breder, 1926; Gray, 1933 c; Bainbridge, 1958, 1960, 1963; Lighthill, 1969, 1970) modes. In contrast little work has been done on the ostraciiform mode. Models have been made along mechanical (Breder, 1926; Gray, 1968, p. 35) and mathematical (Smith & Stone, 1961) lines. How-ever as Gray (1968) points out, ostraciiform locomotion has not been analysed in living fish.

The distribution and activities of animals and plants upon the sandy beach are largely influenced by the special physical factors operating in that environment. The paper is a contribution to the knowledge of these factors.

The tidal ebb and flow, and the resulting alternations of exposure, are the outstanding factors. The extent to which other factors may be operative upon the beach, during the period of ebb-tide, depends upon the vertical distance of the point in question above or below mean sea-level.

Thirty species of sponges (29 Demospongiae, 1 Hexactinellida) have been recorded in association with a white coral bank situated off Cape S. Maria di Leuca (southern Italy) at depths ranging from 430 to 1160 metres. Notwithstanding the occurrence of clearly eurybathic species, two depth-dependent sponge groups can be identified along the bathymetric gradient. Two species, Geodia nodastrella and Plocamiopsis signata, are reported for the first time from the Mediterranean Sea. The sponge assemblage shows a higher affinity with the fauna from the Boreal region, with very low number of Mediterranean endemic species. Systematic notes concerning the poorly known and intriguing species, studied using scanning electron microscopy analysis, are reported.

Like their counterparts at lower latitudes, many Antarctic midwater fish make extensive, diel vertical migrations. However, Antarctic species make these migrations in the absence of two of the three selective advantages generally ascribed to this behaviour. Because the water column is nearly isothermal, there is no metabolic bonus to be gained from thermal differences in habitat depth. Likewise, because their prey do not perform significant vertical migrations, the fish migrations act to diminish rather than enhance their feeding opportunities. For Antarctic midwater fish, the sole advantage of these migrations appears to be the avoidance of visually-cued predators in the upper part of the water column. An evaluation of the relative importance of the three selective factors supports the suggestion that predator avoidance may also be the principal driver of diel vertical migrations for midwater fish at lower latitudes.

A system of nerves (called for short NSV system), described previously in Eledone cirrosa, whose only task appears to be the formation of a fine neuropile in the vena cava, is present also in Sepia officinalis It has a similar disposition to that in Eledone but shows certain special features. It is composed of neurons the cell bodies of which are located in a layer (NSV layer) of the visceral lobe of the brain and in the paired ganglionic trunks, termed the lateral and medial NSV trunks, which emerge from the visceral lobe with the posterior infundibular and visceral nerves respectively. After accompanying these nerves for some distance these trunks take an independent course and give off some tapering branches ending blindly in the loose connective tissue.

Polydora ciliata is a spionid polychaete found below mid-tidal level burrowing in a variety of rocks all of which contain calcium carbonate. It can also penetrate some non-calcareous materials such as rotten wood. It excavates a U-shaped burrow which it lines with a tube composed of mucoprotein and sand grains. This tube has a smooth inner lining of mucoprotein. Both food and tube-building material is collected by the palps and it is suggested that discrimination is made chiefly on size of the particle. Selection is made between the limits of 003-0-05 mm, the smaller particles passing down the gut whilst the larger are used in construction of the tube. A particle selection mechanism is suggested. The function of the segmental mucus glands is to provide the inner lining of the tube.

The problem of chemical penetration of rocks by animals is discussed. P. ciliata uses both mechanical and chemical methods. No acid has been identified, and the use of a sequestering or chelating agent linked with the biochemistry of mucus is suggested.

The life-history of the larva of the prawn Palaemon serratus (Pennant) was studied in the laboratory and found to comprise a variable number of stages, dependent on feeding level and other factors. Larval moulting frequency was relatively constant at 3-day intervals, and could be followed in a population by daily examination for exuvia moult-casts. Length increase at each moult progressed arithmetically, and the highest mortalities occurred during metamorphosis. Consumption of Anemia nauplii by each larva rose from 30 to 400 per day. Populations of isolated animals (i.e. when cannibalism was excluded) were inspected daily and the exact number and duration of larval stages determined. Survival through metamorphosis was very high (over 85%) at both high and low feeding levels, although at the latter the larvae passed through more stages with more erratic duration times. At the end of the experiment, when all the larvae had metamorphosed, the mean dry weights at the high and low feeding levels were 7.7 and o.6 mg respectively. Larval stages could not be positively identified morphologically after stage III unless the history of the individual in question was known. It is suggested that the number of larval stages in the sea may also be very variable and difficult to determine.

Energy-conversion efficiency was calculated from food uptake measurements and larval growth estimations, and was found to be 50–60% during most of the larval life, falling to 35% when the early post-larvae were taken into account.

Measurements have been made of the quantity and type of food assimilated by adult female Calanus helgolandicus (Claus) during the summer months.

Animals kept in the dark at 10° C under a continuous flow of ‘outside’ Plymouth sea water (0·95–2·50 mg insoluble organic material/1.) removed 26·0–66·5 μg/day/Calanus, of which 74–91% was actually digested.

Volumes of sea water filtered daily varied between 10·0 and 36·0 ml./ animal, with an average of 21·5.

The animals preferentially selected a diet of high organic content from the particulate food available, digesting average daily quantities of 18·1 μg carbohydrate, 6·5 μg lipid and 2·7 μg protein.

The average amount of food digested daily accounted for 25·3% of the dry weight and was equivalent to an average respiration rate of 26·5 μl. O2/ animal/day, which adequately accounts for the highest values reported by others for C. finmarchicus (Gunnerus) kept under similar conditions of light and temperature.

These results, which provide direct evidence that Calanus obtains the bulk of its food from particulate material present in the sea, have been discussed with especial reference to Pütter's hypothesis.

The external features of Skeneopsis planorbis (Fabricius) are described and compared with those of Omalogyra atomus (Philippi), Rissoella diaphana (Alder) and R. opalina (Jeffreys).

The foot has a large posterior mucous gland (Figs. 1 and 4, Pm; PI. IV, figs. 1 and 2, Al, Pl), its secretion forming a thread on which the mollusc can climb from one level to another.

Correlated with their small size are modifications of the pallial organs. Skeneopsis, the largest and least specialized, has a bipectinate osphradium, but the gill is reduced to nine filaments; the anus lies well within the mantle cavity. In the other genera osphradium and ctenidium are lost, though the latter may be represented in Rissoella by a small tract of ciliated epithelium. In the absence of a ctenidium the animals depend entirely upon pallial respiration and the stream of water through the mantle cavity is maintained by other means: from the anus strips of ciliated epithelium pass forward to the mouth of the mantle cavity, causing a strong exhalant stream and carrying away the faecal pellets. There is a compensating inhalant flow. The kidney (PI. IV, figs. 1 and 2, K), with its rich vascular supply, has migrated into the tissues of the mantle, increasing its respiratory efficiency.

Plasma vitellogenin synthesis in adult female Scyliorhinus canicula L. continued throughout the year but the rate of synthesis was significantly lower between March and August than during the rest of the year. The hepatosomatic index (liver weight as percentage of body weight) underwent annual variation in both sexes but this variation was considerably more pronounced in the female. Increase in hepatosomatic index in the female was accompanied by increase in the percentage of lipid in the liver and was largely caused by increase in the total lipid content of the liver. Comparison of livers of males and females showed that the percentage of lipid was not significantly different while the percentage of solids insoluble in water and organic solvents was greater in the female. Oviposition, as indicated by the percentage of females with eggs in the oviducts, continued throughout the year, reaching a minimum in September-October. Between July and October, parameters associated with vitellogenesis began recovery from their respective annual minima in the following order: plasma oestradiol level, hepatosomatic index, rate of synthesis of plasma vitellogenin, gonosomatic index, plasma vitellogenin level, rate of oviposition.

Many warm-water (Lusitanian) species reach their limits in the central English Channel, failing to penetrate to the North Sea. We re-surveyed the eastern limits of the Lusitanian intertidal barnacles Chthamalus montagui and C. stellatus, from 1994 to 2004, a decade of exceptionally high sea temperatures, and found range extensions on both sides of the Channel compared to the 1950s and 1970s. Annual recruitment of Chthamalus on the English coast was monitored. There was a consistent gradient of low recruitment to the east of Portland Bill, with significant reductions coinciding with prominent headlands. Highest recruitment occurred during the warmest years. Cluster analysis showed a high degree of similarity of annual recruitment within coastal cells suggesting that local processes are also important. In 1999 we compared recruitment in the other common intertidal barnacles, the boreal Semibalanus balanoides and the non-native Elminius modestus, with Chthamalus spp. All species showed low recruitment between Selsey Bill and Portland Bill, suggesting habitat limitations and/or hydrographic mechanisms. Annual recruitment of Chthamalus at existing limits on the Isle of Wight was positively correlated with the number of days of westerly and south-westerly winds during the summer, coinciding with the pelagic larval phase. A ‘pulse’ of high Chthamalus recruitment on the Isle of Wight, measured during the summer of 2000, reversed population decline. Only a higher frequency of such pulses will maintain populations at existing limits and increase the rate of range extension towards the North Sea. Such extension will be limited by lack of hard substrata, but proliferation of coastal defence schemes in recent years is increasing suitable habitat for barnacles.

The spatial distribution and temporal variations of the Abra alba-Pectinaria koreni community from the eastern part of the Bay of Seine were investigated through four winter surveys (1986, 1987, 1988 and 1991). A grid of 40–67 stations was sampled each year using a Hamon grab (0·25 m-2) for macrofauna collection and sediment analysis. The fauna was dominated by polychaetes and in a lower part by molluscs and echinoderms. Although species richness with ~100 species collected during each survey was high, total density and biomass (±SE) resulted principally from about ten dominant species, and varied between 846·9 ±163·5 and 1135·3 ±186·7 ind m-2 and 23·52 ±4·41 and 27·48 ±4·45 g m-2respectively. The dominant species were patchily distributed and exhibited weak spatio-temporal fluctuations except the two bivalves A. alba and Cultellus pellucidus. Factorial correspondence analysis (FCA) of the distribution of main species among stations and automatic hierarchical classification identified five faunal assemblages which were relatively stable in space and time. The temporal stability of the community could be generated by processes of larval retention near parental population, and sediment stabilization induced by the low abundance of deposit feeders and the high densities of the tube-dwelling polychaete Owenia fusiformis. While the sediment variables were a poor indicator of the spatial structure of the community, the salinity gradient off the Seine Estuary and post-settlement processes (e.g. food limitation and postlarval drifting) have been proposed to explain it. Comparison with an earlier survey (i.e. 1971) suggested a degree of long-term persistence of the community structure in qualitative and quantitative terms.

The movements, abundance, age composition and growth of bass, Dicentrarchus labrax (L.), in the Severn Estuary and inner Bristol Channel have been described from regular samples offish taken from power-station intake screens between 1972 and 1977. Bass began to move into the estuary during late August or September and reached peak abundance between September and early November. The tendency for fish to move seawards in the late autumn and winter may be related to declining water temperatures in the estuary. Likewise, differences in abundance between years appear to be related to annual differences in temperature. Although the populations were dominated by the 0 + age class, successively decreasing numbers of the next four age classes and occasional 5 + fish were also present. Respective mean standard lengths of bass in the estuary at the end of their first to fifth years of life were approximately 65 mm (≡ 4·5 g), 130 mm (≡ 37·9 g), 190 mm (≡ 121·1 g), 250 mm (≡ 280·4 g) and 290 mm (≡ 441.5 g). Growth occurred predominantly between May and September, with the mean standard length of 1 + fish increasing from approximately 65 mm (≡ 4·5 g) to 130 mm (≡ 37·9 g).

Over a period of 10 years, 1964–74, primary production has been measured at three stations across the western English Channel using the 14C method. Results for carbon fixation, cell counts and mean seasonal production are illustrated. Statistical analyses show that, at two of the three stations, carbon fixation in 1966 was significantly greater than expected and that annual production differs significantly at each of the stations. The variations observed are discussed in relation to other changes recorded in the area during the same period. A deck incubator used for simulated in situ14C experiments is illustrated.

Knowledge about harbour porpoise and bottlenose dolphin occurrence in Cardigan Bay Special Area of Conservation (SAC), Wales, is limited to daylight hours during summer, when conditions are suitable for traditional visual surveys. T-PODs are autonomous instruments programmed to log time-cues of species-specific echolocation signals for long periods of time. Here we investigated bottlenose dolphin and harbour porpoise habitat use and partitioning by deploying ten calibrated T-PODs in Cardigan Bay SAC for one year. The T-PODs detected both species all year round with a peak of detections in April–October for dolphins and in October–March for porpoise, revealing a previously unknown importance of the place to harbour porpoise during winter. Though the two species are sympatric, simultaneous detections of both species were rare and indication of temporal habitat partitioning between the two species in some parts of the SAC was observed. The one location where simultaneous detections were not as rare was close to the stretch of shoreline where stranding of porpoises killed by dolphins are most common, suggesting that the observed spatiotemporal overlap leads to inter-specific interactions, in some cases fatal for the porpoise.

The retinae of three species of deep-sea shark, Centrophorus squamosus, Centroscymnus coelolepis and Deania calcea, have been studied. All had goldencoloured photosensitive pigments, similar to those of deep-sea teleosts. The absorption maxima for the unbleached pigments lay between 472 and 484 m/n. The retina of the hake (Merluccius merluccius) was studied for comparison; its retinal pigment absorbed maximally at 495-5 mix. Some observations on the retinae of the moray eel (Muraena helena) and the Atlantic salmon (Salmo salar) are also described.

The lipid class and fatty acid composition of eight geographically disperse isolates of Emiliania huxleyi, grown under 12 h L:D cycles and harvested during logarithmic and stationary growth phases, were examined. Cell size and chlorophyll content tended to decrease from logarithmic to stationary growth phase, Methyl and ethyl ketones were the dominant lipid classes, although proportions exhibited no clear pattern either between strains or growth phases. Neutral lipid hardly accumulated over the course of the growth experiments, and triacylglycerol was either absent or only present at low levels. In all strains with the exception of a South African isolate, levels of total fatty acid per cell decreased markedly between logarithmic and stationary phases, primarily attributable to reductions in the levels of saturated and monounsaturated fatty acids. Major fatty acids in all strains during both growth phases were 14:0,16:0,18:1 (n-9), 18:4 (n-3), 18:5 (n-3) and 22:6 (n-3). Although all strains were rich in polyunsaturated fatty acids (47–72% of total fatty acids) stationary phase cultures consistently contained the highest proportions. The polyunsaturated fatty acid docosahexanoic acid (22:6, n-3) was the most abundant fatty acid in all strains, comprising a maximum of 38·4% of total fatty acids in strain M 181 during stationary phase. Multivariate analysis (PCA) allowed logarithmic and stationary phase cultures to be distinguished although no obvious intra-isolate variability was apparent. The results are discussed in terms of the importance of lipids for the ecophysiology of E. huxleyi and the role of this dominant coccolithophore in the marine food chain.

Recruitment of Semibalanus balanoides at Robin Hood Bay, North Yorkshire, between 1969 and 1981 ranged from almost total failure to ca. 30 spat/cm2. A similar annual pattern over 100 km of adjacent coast appears to implicate climatic or hydrographic factors. Adult fecundity did not vary greatly, but as there was substantial variation in the number of cyprids reaching the shore, events during the planktonic phase (particularly wind-driven larval dispersion) appeared to be of prime importance.

Thereafter, settlement density was modified by cyprid behaviour, except when larvae were very abundant, by the availability of space and the temporal pattern of the settlement. Mortality during early shore life was highly variable, photographic studies in 1981 showing between 1% and 92% of settlers dying within ten days. Under highly desiccating conditions 70% of a single day's input to the upper shore died in the first 24h. Such severe mortality could be compensated for by later inputs as settlement extended over 4 weeks or more, primarily as a result of unexpectedly long and asynchronous release.

The growth of the octopus Eledone cirrhosa has been studied in a population from the North Sea off Aberdeen. Data are presented for the growth of individuals isolated in aquarium conditions; the growth of size classes in thefieldpopulation; and preliminary information on the growth relationships of gonad, somatic, cardiac and brain components of the body.

At 15 °C Eledone cirrhosa is capable of growing from 10 to 1000 g in 270 days. From octopuses which feed readily in captivity, weight specific growth rates of up to about 3–5 % day-1 for animals of 100 g body weight are recorded, falling to a maximum of about 1–5 % day-1 at body sizes above 500 g. Females stop growing when sexually mature, but in the sample captured they were consistently larger than males, a feature which may account for the 7:1 bias towards the incidence of females. On a wet-weight basis, the mean food incorporation into growth is 37 % of the food ingested, which is 49% of the gross weight of crabs killed. Field data for 1978/79 suggest that animals recruited to the population at the beginning of the year grew steadily until December, overwintered without growing, then grew rapidly for several months in the subsequent year before disappearing from the samples. The estimated average age of those animals and by implication, the life span, is 20 months.

A study of the effects of salinity on the distribution and abundance of the amphipod Corophium volutator (Pallas) on the estuary of the River Ythan, Aberdeenshire, indicates that 2‰ is a critical minimum salinity controlling its distribution. In areas with salinities between 2 and 5‰ C. volutator was present, but in reduced numbers. Breeding occurred only in salinities greater than 7·5‰. In areas with salinity greater than 5‰, the distribution and abundance of C. volutator were controlled by the nature of the substrate; however, in areas with suitable substrates, but where the salinity was below 5‰, the effects of salinity override the effects of the substrate. The annual life-cycle is discussed. The results of this study are compared with those of a recent experimental study.