In 1971 and 1972 during the course of short cruises to the South Biscay area on R.V. ‘Sarsia’ several hauls were made with a 100 hook long-line on the Continental Slope at depths ranging from 800 to 3600 m. The hooks used were of two different patterns (Fig. 1) arranged alternately. The hooks were mounted on wire snoods of about 1 m length which were attached to the line at 10 m intervals by stainless-steel snap-on connectors. The object of this arrangement was to find out if the incurving hook pattern based on a traditional South Pacific type of wooden hook showed any advantage over a normal type of hook.

Three new examples of cleaning symbiosis are recorded among the British labridae, Crenilabrus melops, Ctenolabrus rupestris and Centrolabrus exoletus. The first two have only been seen in aquaria although parasites in the stomach of C. melops caught offshore suggests cleaning activity occurs in their natural environment. C. melops has been observed in the public aquarium taking parasites from the bodies of a number of host fish most commonly the pink bream (Pagellus centrodontus). Most cleaning activity occurs after the lights are first turned on when the hosts remain stationary to be cleaned. At this time the incidence of parasites on their bodies is most obvious. Certain areas of the body are cleaned in preference to others. Details are given of cleaning symbiosis by the pipe fish Enterlurus aequoreus, Syngnathus typhle and S. acus.

This investigation of the ultrastructure of the cells of laminarian haptera is part of a more detailed study of the growth of marine macroalgae and their inter-action with the environment. A major section of the programme is an attempt to establish the relationships between physiological, biochemical and structural (including ultrastructural) changes which occur during cell growth in brown algae and to compare such observations with those recorded for higher plant cells.

The choice of haptera (PI. IA) for much of this work on brown algal cell growth is based on their suitability for the interpretation of enzymological data on a cellular basis. Hapteron growth shows several convenient similarities to that in primary meristems of higher plants. Although lamina growth is from an intercalary meristem at the base of the lamina (transition zone), hapteron growth is essentially apical (Reinke, 1876), and differentiating cells are arranged in rows leading backwards from the apex (PI. IB, c). Thus, progressive sections cut from the tip backwards will contain an increasing percentage of vacuolate, elongating cells, as in the flowering plant root.

Vertical and horizontal hauls were taken at approximately fortnightly intervals from April 1969 to April 1970 at L 3 (lat. 40° 17.7′ N, long. 4° 11.2′ W) and L 4 (lat. 50° 15′ N, long. 4° 12.5 W). Thirty-two species of prosobranch veliger were present at L 35 these larvae were not as numerous at L 4 and only 26 species were recorded. The number of species was highest in the summer: the number of veligers was highest in February. After mid October both the number of species and the abundance of veligers decreased rapidly and remained low until early February. Veligers of some species occurred later at L 3 and L 4 than in more inshore waters and these were probably individuals carried beyond tidal influences which would normally lead to settlement on the shore. They included Lacuna vincta, Littorina littorea and L. neritoides.

Veligers of all ages were found at all depths. At their time of greatest abundance veligers of many species occurred maximally at 5 or 10 m, with a variable decrease towards greater depths and a sudden one towards the surface. This distribution later changed giving a proportionally greater number at greater depth. When numbers were low the larvae scattered through the water column with little or no indication of a preferred depth. An examination of the age composition of veligers of rissoids, Natica alderi, Nassarius reticulatus and Philbertia linearis from certain catches showed that the surface accumulation at the time of abundance was composed of a high percentage of young veligers: in an ageing population there was a higher percentage of larvae, especially the older ones, at greater depths, except for Nassarius reticulatus which consistently showed maximal numbers above 10 m until the larvae became scarce.

L. pallidula is more or less confined to Fucus serratus. L. vincta is common on F. serratus but is also found on Halidrys, Laminaria and various Rhodophyceae. Neither species occurs in the absence of these weeds on which they both feed and spawn. Lacuna species are the dominant gastropods on weed at M.L.W.S. at Whitburn, County Durham.

Both species are annuals. In L. pallidula the growth rates of females and males are markedly different, the former growing both faster and over a longer period. Females attain a mean maximum size of 8–4 mm compared with 45 mm for males. L. vincta males and females grow at approximately the same rate, though females usually attain a greater size.

Males predominate in L. pallidula at all times of the year, comprising between 55% and 75% of the population with a mean of 68–6%. Males die slightly sooner than females but there is no more than 4 weeks difference in longevity. Copulation in L. pallidula begins in November and continues to April, with two peaks in January and March.

Spawning commences in January in both species and reaches its peak by April in L. pallidula and by June in L. vincta. Hatching occurs in L. pallidula from April to July. The time of first hatching in L. vincta is not certain but is probably about March. Larval settlement occurs from June to October with a maximum in September.

Density is high following hatching in L. pallidula (> 2000/m2) and settlement in L. vincta (> 300/m2). Dispersion is similar in the two species, being aggregated at high density and more or less random at low density.

The ratio of the concentrations of κ- to λ-carrageenan is shown to be related to the nuclear phase in Chondrus crispus both in culture and in nature. This ratio is low in tetrasporic plants and relatively high in the gametophytes. It was found to vary somewhat amongst samples analysed, but was always less than unity in tetrasporophytes and greater than unity in gametophytic plants. The κ/λ ratio in Gigartina stellata was high in gametophytes as in C. crispus; the tetrasporophytic phase of this species is unknown. It is suggested that the commercial quality of carrageenan can be correlated with the biological status of the harvested plants.

Stromateoid fishes form a small group among the Perciformes, characterized by remarkable toothed saccular outgrowths in the gullet just behind the last gill arch (Haedrich, 1967). Most are associated with medusae when young but are poorly known as adults. In addition to the diagnostic oesophageal teeth, a striking feature of many stromateoids is the curious subdermal canal system, whose function is unknown and whose structure has not been described in detail. The present note describes observations upon the biology of Schedophilus medusophagus Cocco, and upon the structure of its integument.

Competition for space between sessile animals on the seashore and sublittorally is an important factor in their ecology. This is partly because of their density, but also because competition for space between sessile animals is of a more severe kind than occurs between free-living ones, for they cannot move away from their competitors.

The ‘mucous’ tube of Platynereis dumerilii is made up of successive layers of fine threads held together by an adhesive secretion. Tube construction involves a regular sequence of behaviour which can be modified if algae or other objects are available for incorporation into the tube wall. Anterior parapodia are specialized for tube construction and gland cells producing tube components occupy most of the coelom in these segments. Several types of gland cell can be recognized histologically and those which form the threadsdischarge into a complex spiral organ below the cuticle.

Although the anatomy of the coelacanth muscles has been examined very thoroughly, their protein composition has, until recently, not been investigated. Thanks, however, to the 1972 British–French–American expedition to the Comores, frozen material has been made available and some results on myoglobin and four glycolytic enzymes have already been published. We have carried out a comparison of the sarcoplasmic proteins of red and white muscle by starch-gel electrophoresis. The ninhydrin-positive dialysable constituents and the myofibrillar proteins of white muscle have also been examined.

A few puzzling results obtained with the white muscle extracts have been related to the occurrence of o.1 M ammonia, due presumably to the splitting of urea by a bacterial urease, and to an alteration of the active thiol groups of GAPDH and PK. If due account is taken of these unusual post-mortem changes, the extractability of the proteins and their properties are strikingly similar to those of teleosteans. The comparison of the sarcoplasmic proteins of white and red muscle by starch-gel electrophoresis revealed also that the differentiation observed in the coelacanth was similar to that occurring in the carp. A study of the low-molecular-weight proteins, or parvalbumins, of white muscle and of the myofibrillar proteins also shows the expected differences between the two muscle types.

The only abnormal features observed in this study were the high concentration of parvalbumins, 1.5–2 times that found in other species examined, and the occurrence of an unusual globulin fraction which was easily extracted at ionic strength 0.5 and insoluble at ionic strength 0.35 and neutral pH.

Occasional reference to the sporadic appearances of silicoflagellates (commonly Dictyocha spp.) are to be found in a number of seasonal studies of phytoplankton in the coastal waters of the British Isles. The silicoflagellates are rarely described in any detail since they usually form a small component of the annual phytoplankton. The autumnal occurrence of silicoflagellates in the Firth of Clyde was briefly described by Marshall (1924) in an account of the food of Calanus, and further seasonal observations on silicoflagellates in European coastal waters are to be found in the works of Margalef (1965), Nival (1965), Travers & Travers (1968) and Ignatiades (1970). Numerous studies on silicoflagellates have been concerned with their taxonomy, particularly the plasticity of form shown by their tubular siliceous skeletal structures and the many taxa (fossil and living) so far described. The confusion which has arisen through the differing views of palaeontologists studying fossil material, and botanists working with live populations and their seasonal abundances, has been highlighted recently in a culture study of Dictyocha fibula, in which skeletal variations in a single clone were matched with a number of other entities, fossil and living (Van Valkenburg & Norris, 1970).

The locomotor roles of the myotomal muscles of fish are dependent on swimming speed. The mean maximum sustained swimming speed for coalfish (Gadus virens L.) during a 6-h period in an experimental exercise chamber was determined using a fixedvelocity technique and found to be 4 bodylengths/s. Biochemical measurements were made on the concentration of glycogen and lactate in the red muscle and white muscle at a series of known swimming speeds. Evidence is provided that red muscle alone is used at speeds below 2 bodylengths/s. The fall in concentration of red muscle glycogen was directly proportional to increased swimming speed. At speeds in excess of 2 bodylengths/s a statistically significant increase in lactate concentration occurred in the white muscle fibres. A reduction in glycogen content of the white muscle was also noted at speeds at and above the estimated mean sustained swimming speed. These results are discussed in the light of the current ideas pertaining to the division of labour between myotomal muscles in fish.

A nocturnal larval hatching rhythm is described for the lobster Homarus gammarus. In natural illumination cycles, hatching takes place shortly after darkness with the hatching process lasting for about 1 min or less. One female lobster can release batches of larvae each successive night for periods of from 2 to 6 weeks, depending on size and water temperature during the period of hatching. The hatching rhythm persists, though slightly out of phase, when lobsters that have been releasing larvae for some time are kept in constant darkness, but in constant illumination hatching may be delayed for 2 or 3 days and when it does occur it is erratic and non-rhythmic. Larvae that do hatch in constant illumination appear to do so without parental assistance. Onset of darkness synchronizes the rhythm but an endogenous component is involved in controlling it.

In a previous paper Bayne & Thompson (1970) showed that temperature and nutritive stress resulted in a decline in body condition of mussels, Mytilus edulis, when kept in the laboratory. Both carbohydrate and protein were lost from the body tissues but the losses (as a percentage of the initial values) were greater from the germinal (mantle) than from the somatic (non-mantle) tissues. In spite of the loss of body reserves, M. edulis was able to continue maturation of the gonad during the autumn to spring period. In the early summer, however, when the gametes were fully ripe, stress resulted in a recession of the gonad and a rapid loss of protein from the mantle tissues. A similar decline in condition index and loss of glycogen and protein has been reported for adult oysters, Ostrea edulis, when maintained under hatchery conditions (Gabbott & Walker, 1971).

The results of decapod lipid analyses have shown that females and gravid females generally contain high levels of monounsaturated acids and that the eggs of some of these decapods are composed mainly of phospholipid and triglyceride. These are probably present mainly as energy reserves. The percentages of saturated fatty acids are not found to vary with either maturity or sex, whereas the composition of the polyunsaturated acids are affected by both sex and maturity differences. Females are generally much lower in their content of polyunsaturated acids than juveniles and males, the males showing a greater requirement for 20:5 acid compared to the females.

For the euphausiids there is a slightly different picture, the monounsaturated acids appear as the stable fraction and for Euphausia krohnii the juveniles are similar to the females in their content of the polyunsaturated acids.

Neomysis integer is quite unlike the oceanic crustaceans showing a very specific difference in fatty acid composition between the males and females, the juveniles being rather intermediate in composition.

Growth of the littoral harpacticoid copepod Tigriopus brevicornis O. 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.

Analysis of the carotenoid pigments of decapod crustaceans has indicated that the visible differences in the appearance of species from different depth horizons are largely due to the disposition of pigments and not to differences in total amount of pigment relative to body size. Species from the upper mesopelagic zone have relatively few large chromatophores, and their chitin is either unpigmented or feebly pigmented. Species from deeper zones have very many small chromatophores and chitin heavily pigmented by unesterified astaxanthin. The major carotenoid pigments of almost all species are astaxanthin and its esters.

Lipid analyses have shown that several species of Caridea have very high levels of lipid in the body, and that in many deep-water species wax esters comprise a large proportion of the total lipid. Specific patterns of distribution of the various lipid classes are found in different tissues, with wax esters particularly dominating the hepatopancreas lipids of deep-living species.

The patterns of pigment and lipid distribution are discussed in relation to the depth distribution, light environment, and metabolic requirements of the different species.

All species of the Mysidacea (Crustacea) lay their eggs into a marsupium, thus allowing direct counts of brood sizes to be made. The different forms of the young stages in the marsupium are closely similar in all species. The most detailed embryological studies are those of Manton (1928) on Hemimysis lamornae (Couch), Wagner (1896) and Needham (1937) on Neomysis integer (Leach), and Nair (1939) on the tropical species Mesopodopsis orientalis (W. M. Tattersall). Kinne (1955) describes and figures the general body forms of the different stages of development of the larvae in the marsupium of Neomysis integer; Vannini (1930) examines the larvae of Leptomysis lingvura (G. O. Sars), while Kane (1904) illustrates the most advanced larval stage of Mysis relicta Lovén. The larvae of several non-British species have been described -Boreomysis arctica (Kröyer) by Jepsen (1965), Mysidium columbiae (Zimmer) by Davis (1966) and Neomysis intermedia Czerniavsky by Murano (1964b).

Although a great deal is known about methods for the culture of commercially important bivalve larvae (see, for example, Loosanoff & Davis, 1963; Walne, 1964, 1966) little information is available on the biochemical changes that take place during larval development.

Collyer (1957) determined the glycogen content of several batches of newly released larvae of Ostrea edulis and found that viability was not related to the initial glycogen content. Millar & Scott (1967) showed that lipid was the major energy reserve used during starvation by newly released O. edulis larvae. Recently Helm, Holland & Stevenson (1973) have shown that the initial growth rate of newly released O. edulis can be positively correlated with the lipid content of the larvae on liberation.

The present paper describes the biochemical changes that occur during larval development, metamorphosis and early spat growth of O. edulis. In addition, short-term starvation experiments were carried out to determine whether protein, lipid or carbohydrate serves as the main energy reserve during each phase of development.

Three levels of oxygen consumption rate are identified, viz. standard, routine and active. Animals fed above the maintenance energy requirement adjust their oxygen consumption rate to a routine level. Animals fed below the maintenance requirement reduce their oxygen consumption rate to a standard level within 35–40 days. The routine rate is seasonally variable, with high values in the winter and low values in the summer. The standard rate also varies seasonally. The exponent that relates routine oxygen consumption to body size varies from a high value in the summer to a lower value in the winter.