The growth of littoral and sublittoral barnacles has been studied in some detail using linear, surface or volumetric measurements (see Barnes & Barnes, 1959). The growth curve in terms of linear dimension generally included an extended straight section which implies, assuming a constant shape, that the volume is increasing with time in proportion to the area (Crisp, 1960). Hence a plot of basal diameter against time is the simplest characteristic of the growth during most of the life of an isolated specimen. In most studies the shells are measured at daily, weekly or monthly intervals and the effect of different factors on growth evaluated. Thus, it has been claimed experimentally that many factors influence directly the growth of barnacles. These factors and their effects are outlined in Table 1.

The development of the planktonic veliger larva of Mytilus edulis L. culminates in a swimming crawling stage during which the foot is of considerable importance in the selection of a settlement site. This stage has been described for many other bivalves (see Bayne, 1965) and has been given the term ‘pediveliger’ by Carriker (1961). The pediveliger of Mytilus edulis is negatively phototactic and positively geotactic during velar swimming (Bayne, 1964b) and is usually confined to water layers close to the substratum. The foot may be protruded during swimming and if it comes into contact with the substratum it adheres and a period of crawling commences. During crawling the larva progresses on the ventral or posterior surface of the foot by means of ciliary and muscular action. Crawling may result in attachment by secretion of the first byssus thread or alternatively the foot is withdrawn and velar swimming is continued until the next exploratory crawling phase. Mytilus larvae attach most readily to filamentous substrates in the field (Blok & Geelen, 1958; Bayne, 1964a).

Most work in tunicate heart physiology has been directed towards finding the actual physiological cause of heart reversal rather than the adaptive advantage of it to the animal (see reviews by Krijgsman, 1956; Kriebel, 1968; Goodbody, 1974). Krijgsman (1956) concludes: ‘We do not know whether there is any functional significance in the periodic reversal of beat. One can see no reason why a permanent one-way circulation should not be efficient. Presumably the cause of reversal is the periodic exhaustion of the pacemakers, which has no physiological significance.’ Because of the abundance of pacemaker systems in nature in which periodic exhaustion does not take place, this conclusion should be re-examined.

In an earlier study of the biochemical composition of barnacle cement, Walker (1972) found that the cements of two sessile barnacles, Balanus hameri and B. crenatus contained small amounts of lipid (< 1% of total dry wt.) and carbohydrate (♎ 2% of total dry wt.) but were mainly composed of protein ( > 85 % ° of total dry wt.). Lindner & Dooley (1973) similarly found that a large proportion of B. crenatus cement was protein (80%), but Cook (1970) found only 70% protein, lipid (27.4%) being the other major constituent. There is therefore general agreement that barnacle cement is mainly a proteinaceous secretion, but controversy still exists over the amount of lipid present.

An important factor in the seasonal cycle of phytoplankton growth is the establishment and breakdown of the seasonal thermocline (Sverdrup, Johnson & Fleming, 1946). When surface heating is sufficient, more buoyancy is produced than can be dissipated by wind and tide. The stabilization of the water column allows the phytoplankton sufficient time in the surface layer to utilize the light energy for increased net production and the spring bloom is triggered. At the end of the summer period the erosion of the thermocline may result in an increase of nutrients in the upper layers. If production has become limited by surface depletion of nutrients during the summer, then the thermocline breakdown may result in an autumnal bloom particularly if a period of calm sunny weather follows. The importance of the thermocline development and season length is clearly illustrated in plankton studies of the North Atlantic, for example Robinson (1970).

Recent improvements in gear and techniques have permitted much more detailed studies to be made of vertical distribution patterns of pelagic oceanic organisms (Vinogradov, 1970; Foxton, 1972). One such development is the RMT 1 + 8 opening-closing net system for sampling plankton and micronekton (Baker, Clarke & Harris, 1973) which can be acoustically monitored in situ for fishing depth, water temperature, flow and net operations. This sampler has been used to study the midwater communities in the N.E. Atlantic over the last 6 years during cruises by RRS ‘Discovery’. It has been successfully operated to depths of 4000 m.

The larval cement of Ostrea edulis is formed from material secreted by the settling larva from two types of pedal gland (Cranfield, 1973b). Light microscope observations suggested that there were fibrous regions in this cement. The histochemistry and ultrastructure of the cement were therefore examined to establish the nature of this fibrous structure and to determine the part each of the two secretions might play in its formation.

The quantitative zoogeography of pelagic zooplankton is a subject very much in its infancy. This is due to a number of causes; firstly, the taxonomy of a large number of animal groups has not been finalized and new species are still being regularly discovered. Secondly, many samples, especially from the earlier expeditions, were obtained from broad depth ranges and without accurate depth measurements or the use of opening-closing nets. This latter problem has been overcome by modern sampling devices (e.g. Baker, Clarke & Harris, 1973).

Underlying the thinking of a lot of previous workers has been the hypothesis that the water masses of the various oceans (usually delineated by means of temperature-salinity relationships (Sverdrup, Johnson & Fleming, 1942)) support a distinct fauna. This point of view has been summarized by Johnson & Brinton (1963), Banse (1964) and Beklemishev (1966, 1971). Examples of studies in which the relationship of species distributions to water masses have been studied are Pickford (1946; the cephalopod Vampyroteuthis infernalis), David (1958,1963; chaetognaths), Bieri (1959; Pacific chaetognaths), Brinton (1962; Pacific euphausiids), McGowan (i960; the worm Poebius meseres) and Haffner (1952; the fish genus Chauliodus). In the last case it was suggested that the oxygen content of the water was also an important factor.

The most comprehensive hydrographic work on the English Channel, even today, is that of Lumby (1935). Lumby used the surface observations of ships of opportunity (steamers on regular routes) that were gathered over a period of 25 years from 1903 to 1927. The number of observations gathered runs into tens of thousands and these were subdivided into convenient regions for the purpose of constructing an Atlas of sea surface temperature and salinity. The mean monthly values of temperature for each region from which the monthly contours were drawn can be considered as established to within ± 0.2 °C. Despite the fact that these data have been available for half a century no satisfactory explanation for these monthly temperature distributions has been offered. In this paper the role of horizontal turbulence in redistributing the net surface heating to produce these monthly temperature distributions is quantitatively examined.