Ontogenesis of the eyestalk structures in Palaemon serratus has been studied during the larval and postlarval life by means of scanning electron microscopy (SEM) and light microscopy (LM). At hatching, a larval sensory pore is observed in the zoea. The organ of Bellonci is present with its typical onion bodies. During larval life, this organ grows and differentiates. Vacuolization in the organ of Bellonci starts in stage 4. At the same time, the giant neuron appears, but the sinus gland cannot be recognized before stage 5.

During larval life, vesicular cells are present in the optic medullae with an increase during stages 4 and 5. The differentiation of the neurosecretory cells of MEX (medulla externa X-organ) and MTGX (medulla terminalis ganglionaris X-organ) occurs with metamorphosis. The main sensory pore appears with metamorphosis and becomes clearly visible in postlarval life.

The movements of the structures, which occupy different positions in larvae and adults, are described in relation to the longitudinal axis of the eyestalk. A schematic representation explains the torsion of the eyestalk and the dynamics and growth during the formation of the eyestalk structures.

While examining collections of young fish taken with a 2 m stramin net on the west coast of Scotland in 1975 for the unstaffnage Marine Research Laboratory of the Scottish Marine Biological Association I found two postlarvae unlike any I have seen before.

These two specimens, both about 6.2 mm long, were taken on 31 July 1975 from the Tiree Passage between the Islands of Mull and Tiree, and from Bloody Bay on the south-west coast of Mull.

The distributions of Corophium insidiosum and C. bonnellii on the shores of Northumberland and Tyne and Wear suggest the former species to be common in areas of high turbidity, and the latter species in relatively clean conditions. In C. insidiosum breeding takes place throughout the year except during the months of November and December when mature females enter a ‘resting’ stage and immature females delay the onset of maturity. There are two main generations per year. Egg production is linked to a semi-lunar rhythm with peaks around the times of spring tides. Fecundity, brood mortality and feeding activity each vary seasonally.

Collections of bottom-living animals from the continental slope of the northern Bay of Biscay contain a new species of Oligobrachia; this increases the number of species of Oligobrachia known from the North Atlantic to five. Oligobrachiids are quite frequently found incubating embryos and five individuals of the new species carry embryos. Oligobrachia embryos have been studied morphologically already (Ivanov, 1957, 1975; Southward & Southward, 1963; Brattegard, 1966; Ivanov & Gureeva, 1976) and should prove useful material for experimental studies in future. Incubation is also known in the family Siboglinidae, but neither embryos nor larvae have been seen in any other pogonophoran families. The Biscay collections also contain additional specimens of Oligobrachia ivanovi and these have been useful in revising the description of this rather rare species.

The bivalve mollusc Scrobicularia plana (da Costa) is very common in the estuaries of South-West England and lives in permanent burrows in intertidal sediments ranging from soft mud to fairly hard sand and sometimes gravel. Although it obtains some of its food by filtering the overlying water, Scrobicularia is mainly a deposit feeder (Hughes, 1969). In addition to its widespread distribution, Scrobicularia has several features which make it attractive as a possible indicator organism for metallic contamination. It is more tolerant of low salinities than most common estuarine bivalves, usually penetrating farther upstream than Macoma balthica, Mytilus edulis and Cerastoderma edule (Percival, 1929; Spooner & Moore, 1940; Bryan & Hummerstone, 1977). Also, it lives for over ten years, usually attaining a length of 4–5 cm, and its rate of growth can be estimated from rings on the shell (Green, 1957; Hughes, 1970).

The Crustacea play an important economic role in the marine and aquatic environments not only as a food source but also in the productivity of the fisheries. Exploitation of these resources has led to a need for intensive culture methods which impose physiological stress on the animals and consequently increase the incidence of disease. The need to reduce the lethal and debilitating effects of pathogens has stimulated a renewed interest in the defence mechanisms of the Crustacea.

A steroid that binds with mammalian oestradiol-17β antibody has been detected in Calanus helgolandicus Claus, collected from Plymouth Sound, and in Calanus finmarchicus Gunnerus captured off the coast of Norway. The specificity of the antibody, together with the chromatographic behaviour of the steroid on Sephadex LH-20, supports the view that the compound is the sex hormone oestradiol-17β (E2). The antibody has been used in measuring the amounts of E2 in the animals by radioimmunoassay, a technique not previously employed in studies with zooplankton and therefore described in detail.

Specimens of Pagurus bernhardus (with and without shells) were exposed to both gradual (sinusoidal) and abrupt (square-wave) salinity fluctuations and changes in haemolymph osmolality, tissue water content and oxygen consumption monitored. Oxygen consumption was also monitored under steady-state conditions; under these conditions there was no significant difference between the rate of oxygen consumption by animals with shells and animals without shells. Oxygen consumption was found to vary with body weight according to the equation O2 consumption = 0·292 W0·668. During exposure to fluctuating salinities the crabs with shells were seen to increase loco-motory activity when the external medium declined to approximately 75% sea water. Haemolymph osmolality values followed the same pattern of change as the external medium; the haemolymph of crabs without shells became significantly more dilute during exposure to low salinity than did that of crabs with shells. P. bernhardus showed significant increases and decreases in hydration level as salinities fell and rose respectively. Crabs with shells showed a marked temporary increase in oxygen consumption when the external medium declined to approximately 75% sea water; crabs without shells showed no such response. The importance of the shell as a means of protection against dilute media is discussed.

The ecology and feeding behaviour of Antedon bifida bifida (Pennant) were studied in situ at five sites on the east and west coasts of Ireland. These encompassed a range of different habitats and hydrographic conditions, including currents of varying intensity, oscillations due to wave action, and multidirectional water movements.

Unlike other comatulids hitherto studied, this species was found to be relatively unspecialized in its choice of habitat and to display great flexibility of movement in its arms and pinnules which enable it to adapt to and feed in each of the different types of water movements described. Neither diurnal nor tidal feeding rhythms were observed, the animals being found to feed almost continuously. The relatively unspecialized nature of this species is discussed in relation to the almost cosmopolitan distribution of the genus Antedon.

Rainbow & Walker (1977) have described the histology, histochemistry and ultrastructure of the barnacle alimentary tract and this study continues the overall investigation into barnacle digestive physiology. Possible sites of alimentary absorption in the barnacle tract have been proposed from histological (see Törnävä, 1948) and histochemical and ultrastructural evidence (Rainbow & Walker, 1977) but no direct studies on sites of absorption have previously been made. Similarly, although it has long been known that barnacles produce discrete faecal pellets (Darwin, 1851), the time interval between ingestion and defaecation has not been determined.

In spite of a specialized shell structure and an obligate coral-inhabiting mode of life, B. anglicum retains a generalized balanoid operculum, cirri and mouthparts. These are used to capture and ingest live planktonic prey such as nauplii. Prolonged cirral extension is a preliminary to prey capture but the capture process itself involves the beating down of the prey by a series of up to six contractions and extensions of the cirri in 7–10 s. The prey is then grasped by the extended third maxillipeds (cirrus III) and drawn into the mantle cavity. An antenniform exopod of cirrus I is extended and detects the prey at the beginning of the capture sequence. The exopods of cirrus I are also used in the rejection of any unwanted particles grasped and taken in by the third maxillipeds.

The majority of studies of the physiological ecology of organisms have been concerned with changing a single environmental variable at a time, but more information on the relationships between biological responses and environmental factors would be provided by experimental techniques that emulate the multi-dimensional character of the natural environment.

During surveys of rocky shores in Shetland, the Australasian barnacle Elminius modestus was found at 3 out of 42 transect sites and at 6 out of 11 shores searched for its presence. Large populations were present only in Vidlin Voe with a few individuals present at other sites including Lerwick Harbour. These observations extend the northern recorded limit of distribution of E. modestus by approximately 450 km.

The spread of the Australasian barnacle Elminius modestus Darwin along the coasts of the British Isles has been followed with interest by marine biologists since the animal was first found in the region of Portsmouth in 1946. Crisp (1958) describes the spread of Elminius up to 1957 and reviews the factors which are important in encouraging or restricting the spread of the species. On the west coast of Scotland, Elminius is common in the Clyde and a few individuals have been recorded on settling panels in Dunstaffnage Bay near Oban (Barnes & Stone, 1972). On the east coast of Scotland, Elminius is known to be common in the Firth of Forth and a few individuals have been recorded from the Tay Estuary (Jones, 1961). Thus, the previous recorded northern limit of distribution of Elminius modestus lies at about 56° 30′ N. Our brief report describes how Elminius has now been found in the northernmost part of the British Isles.

As a part of the programme designed to monitor the effects of the oil terminal now being built at Sullom Voe on the north-east coast of the Shetland mainland, we have been concerned with the survey of plant and animal populations on rocky shores.

Nassarius reticulatus, like most other members of the Nassariidae and Buccinidae, is a scavenger. It apparently relies on the rapid detection and location of a food supply which is intermittently and unpredictably available. The olfactory reactions of Nassarius species are well-adapted for finding dead or damaged animals (Copeland, 1918). Stimuli indicating the presence of food provoke an impressive increase in activity of most starved Nassarius (Dimon, 1905; Copeland, 1918). Recently-fed whelks, however, often fail to respond to the same stimuli (Crisp, in preparation).

In nature, organisms are subjected to a variety of environmental factors acting together and they respond to the total resulting stimulus rather than to single environmental variables. In addition, the animal's response is not in terms of individual physiological rates but rather as a whole organism. Therefore an experimental approach to an animal's response to a complex environment could usefully include (a) multivariate experiments and (b) integration of individual physiological processes to provide a greater under-standing of the ‘whole organism’ response. In this paper, non-linear multiple regression equations and response surfaces are used to describe and illustrate the combined effects on the common mussel, Mytilus edulis L., of body size, ration and season on physio-logical integrations such as the scope for growth, growth efficiency and the oxygen: nitrogen ratio (reviewed by Bayne, 1975; Bayne, Widdows & Thompson, 1976). The data used to compute these physiological integrations are derived from a series of multivariate experiments described in a preceding paper (Widdows, 1978).

Of nine northern European species of the Gadidae examined in the aquarium, or in cages in the sea, four produced sounds. The vocal species were the haddock, Melanogrammus aeglefinus (L.); the cod, Gadus morhua L.; the lythe, Pollachius pollachius (L.); and the tadpole-fish, Raniceps raninns (L.). The main differences between the calls of the vocal species lay in their temporal structure, all the calls being divisible into brief pulses of low frequency sound, repeated at different rates and in different groupings. Calls with this structure yielded spectra with a series of spaced harmonics, the frequency spacing depending upon the pulse repetition rate.

Sixteen additional species were dissected, and seven of these showed well developed muscles attached to the swimbladder, similar to those found in the four vocal species. The remaining nine species, together with the five non-vocal species examined in the aquarium, lacked the muscles.

The behavioural significance of the calls and the operation of the sound producing mechanism are discussed.

Analysis of the deposit-feeding bivalve Scrobicularia plana (da Costa) has been proposed as a method of assessing the biological availability of heavy metals in estuarine sediments (Bryan & Hummerstone, 1977; Bryan & Uysal, 1978). Scrobicularia has a number of attributes which are useful in this type of indicator: (i) it is common in many British estuaries, particularly in the south, and often penetrates much farther upstream than other common bivalves such as Mytilus edulis; (ii) it is a convenient size for analysis and, during its life span of perhaps 10 years, reaches a shell length of 40-50 mm (Green, 1957; Hughes, 1970); (iii) it is a good accumulator of metals and appears to reflect changes in their biological availability.

The bryozoan benthos of the European continental slope is attracting attention after a long period of neglect. Expedition reports, such as those of the ‘Challenger’ (Busk, 1881, 1884, 1886; Waters, 1889), ‘Travailleur’ and ‘Talisman’ (Jullien, 1882; Calvet, 1906), and ‘Hirondelle’ (Jullien & Calvet, 1903) made important contributions to our knowledge. Such monographs have been supplemented by shorter papers dealing with the Bryozoa of offshore banks and island groups (Guérin-Ganivet, 1911; Norman, 1909) or of limited areas within the European region (Duerden, 1893; Nichols, 1911). Following the recent increase of interest in offshore benthos generally, the papers of d'Hondt (1970, 1973a, b, 1974, 1975) provide much new information on the slope and outer shelf bryozoan fauna. However, many of the often enigmatic species of earlier authors have yet to be redis-covered, and d'Hondt has shown that a high proportion of the Bryozoa collected comprises species new to the area or new to science. Clearly, the study of many more collections will be necessary before any comprehensive account can be given.

The structure of the fifth pair of pleopods, modified as secondary sexual characters, in male Euchaeta norvegica is described in detail. The pleopods are biramous. The right pleopod, of relatively simple structure, is used solely to grasp the urosome of the female during transfer and placement of the spermatophore. The left pleopod is complex in form and is used to grasp the spermatophore as it is extruded from the ductus ejaculatorius. The method of grasping the spermatophore is described. The optimal mating position is deduced from the structure and functioning of the pleopods.

The compositions of the lipids of egg yolk, blood plasma and liver of Scyliorhinus canicula from the Irish Sea were examined by column chromatography and by various other methods. Considerable differences in composition were found between these three tissues. Phospholipid and triacylglycerols were the major components of lipids of yolk and liver respectively. Cholesterol, free fatty acid and phospholipid were present in all three tissues. Squalene and alkyldiacylglycerols were present only in traces, if at all. In this paucity or absence of squalene, this population differs from Mediterranean S. canicula. The compositions of the lipids of the livers of six shark species (Scyliorhinus canicula, Scyliorhinus stellaris, Squatina squatina, Galeorhinus galeus, Mustelus asterias and Squalus acanthias) were compared by thin-layer chromatography. In all cases, triacylglycerols were the major components, while hydrocarbons were not detected by this method in any of the species. Alkyldiacylglycerols were present as a major component only in Squalus. Qualitatively, the other five species showed only minor differences from each other; these five species are largely confined to shallow coastal waters. The results follow previous work in showing that low-density lipids, such as squalene and alkyldiacylglycerols, are major components of hepatic lipid in shark species from deeper waters, although not necessarily from great depths. An attempt is made to explain the prevalence of such lipids in pelagic sharks in evolutionary terms. It is suggested that they may serve as an analogue of the swimbladder of teleosts.