Age and growth were estimated in the European squid, Loligo vulgaris, by examining growth increments in the statoliths of 203 specimens collected from off the French Mediterranean coast. Length and increment data were analyzed assuming that the increments were formed daily. The relationships between age and length showed that: growth rate varied considerably among individuals; growth was double exponential; the squids grew on average to 240 mm ML at 240 d from hatching, with a maximum of 350 mm at 240 d; the life span is probably about one year.

Samples of female lllex argentinus were taken from the catch of a Japanese squid jigging vessel on the Patagonian Shelf during March 1986. Morphometrics of the somatic and reproductive organ systems and the histological structure of the mantle in relation to maturation were examined. The data suggest that growth and maturation occur simultaneously during most of the time that lllex argentinus females are on the feeding grounds. In a squid of a ‘standard’ mantle length the whole body mass increases relative to mantle length during maturation and growth of the reproductive organs. This is accompanied by a small but significant decrease in the relative mass of the mantle, head and viscera whilst the mass of the digestive gland remains constant. Although mantle mass of a ‘standard’ female squid decreases relative to mantle length with maturity this is not associated with degeneration of the mantle muscles. Energy and nutrient resources for maturation are apparently derived from the squid's food, not from reserves, and during the course of maturation there is an increasing shift of emphasis from somatic growth to production of gonad and accessory reproductive organs.

Samples of male Illex argentinus were taken from the catch of a Japanese squid jigging vessel on the Patagonian Shelf during March 1986 and an analysis was carried out on the morphometrics of the somatic and reproductive organ systems in relation to maturation. The data show that growth and maturation occurred simultaneously during most of the time that Illex argentinus males were on the feeding grounds over the southern Patagonian Shelf. In a squid of a ‘standard’ mantle length the whole body mass increased relative to mantle length during maturation and this could be attributed to the increase in mass of the reproductive and accessory reproductive organs. During maturation the mantle and digestive gland mass showed no significant change relative to mantle length. The mass of the head increased and the mass of the viscera decreased relative to mantle length. In male Illex argentinus, as in the female, the energy and nutrient resources for maturation are derived from the squid's food and during the course of maturation there is an increasing shift of emphasis from somatic growth to production of gonad and accessory reproductive organs. The proportional investment of body mass in reproductive and accessory reproductive organs predicted for a fully mature male Illex argentinus was less than half that of the female.

The timing of spawning and recruitment in the squid Loligo forbesi in Scottish waters is described on the basis of data from three sources: monthly samples of squid caught by commercial trawls (1986–1988), egg masses found by fishermen (1987–1991), and statistical data on animals caught by research trawls (1978–1987).

Spawning females were present in samples from December to June, with peak spawning occurring in March. Most records of egg masses were from these months, but eggs were also found in August and September. These results suggest that there is an extended spawning season.

Small squid (≤100 mm dorsal mantle length) were rarely present in commercial samples, but were recorded in research samples almost all year round. Thus there appears to be more or less continuous recruitment into the catchable population.

The results of the present study are consistent with published data from other parts of the geographic range in that there is a regular seasonal peak in spawning, and spawning adults disappear from the population in summer. Further interpretation of the life-cycle of this species is not justified on the basis of current knowledge, and more information is needed on migrations, geographical variation, and lifespan in Loligo forbesi.

Nautilus can survive for long periods in water of very low oxygen content. Below a PO2 of around 25 mm Hg activity becomes intermittent, with brief periods of jet propulsion punctuating longer (typically 15–20 min) periods at rest. During these inactive periods ventilatory movements cease and the heartbeat slows to one or two cycles of very low amplitude per minute. The onset of an active period is heralded by an increase in heartbeat frequency and amplitude and a resumption of visible ventilatory movements. The large blood volume and very high oxygen affinity of the blood pigment apparently ensure that the animal accumulates sufficient oxygen during the resting intervals to fuel the brief active periods. Recovery, even after prolonged exposure to near anoxic conditions, is very rapid if the animal is exposed to well-aerated water. These capacities are not only related to a strategy of defence by withdrawal but would also allow Nautilus to exploit environments where the low oxygen content might limit competition from most fish and crustaceans. It is argued that a Nautilus-like physiology and behaviour could well have contributed to the success of extinct ectocochleate forms, living in oceans that were, by and large, less well oxygenated than now. The downward extension of oxygen-rich water and progressive elimination of hypoxic regions from the continental shelves during the Mesozoic may have contributed to the extinction of the ectocochleates by opening up the hitherto hypoxic environments, which they were adapted to exploit, to the more strictly aerobic high metabolic rate competitors and predators that eventually replaced them.

Cadmium uptake, storage and metabolism has been studied in the digestive gland and remaining tissues of the intertidal gastropod Littorina littorea (L). Accumulation of cadmium was linear with time in both of these compartments in individuals exposed to a range of cadmium concentrations (4, 40 and 400 μg Cd l−1).

The subcellular distribution of cadmium in the digestive gland and remaining tissues of Littorina littorea reveals that most of the metal is bound to metallothionein, even in controls, and that cadmium associated with metallothionein increases in proportion to cadmium concentrations in the surrounding water.

Measurements of metallothionein, made by differential pulse polarography showed that, in the digestive gland, concentrations of this metal-binding protein are not significantly affected by cadmium exposure, while in the remaining tissues they are dose-related.

The inherently high levels of metallothionein in the digestive gland of L. littorea explain the role of this tissue as a major site for cadmium storage. However, the lack of significant de novo synthesis of metallothionein in response to cadmium, together with polarographic interferences from high molecular weight thiolic proteins, reduces the value of this tissue preparation as a means of detecting sublethal responses to metals.

Alterations of the biochemical composition and survival of the rotifer Brachionus plicatilis have been investigated. During starvation the proportion of total protein increased from 45·3 to 62·7% while that of total lipid, carbohydrate and glycogen decreased from 20·1 to 6·9%, from 21·2 to 14·1% and from 17·3 to 4·9% dry weight, respectively. The proportion of polar lipids and free sterols in total lipids increased, from 8·3 to 32·0% and from 29·2 to 58·3% whereas triacylglycerol decreased from 54·7 to 4·2% dry weight. The most abrupt alteration in these fractions took place in the interval from 24 to 48 h. The proportion of monoacylglycerols, diacylglycerols, free fatty acids and esters of waxes and sterols in-creased from 1·2 to 3·0% (72 h), from 0·2 to 1·8 (48 h), from 0·7 to 2·4 (72 h) and from 5·7 to 12·1% (48 h) and then decreased to the level of 1·1, 0·9, 1·2 and 1·3%, respectively.

The bass Dicentrarchus labrax is found in the eastern Atlantic Ocean from Morocco (30°N) to southern Norway (60°N) and in the Mediterranean and Black Seas (Whitehead et al., 1986). Throughout its range the bass is an important commercial species and in the waters around the British Isles it is exploited both by commercial fishermen and by sport anglers.

Since the early 1970s the recorded landings of bass have increased considerably (Pickett & Pawson, 1991). The increased exploitation and the conflict of interest between sport fishermen and commercial bass fishermen have been the subject of a multitude of articles in the fishing press calling for greater stock management. Detailed knowledge of the stock structure was required to provide advice on the management of the UK bass fishery (Pawson & Pickett, 1987).

Prior to 1980, tagging studies were conducted off the southern coast of Ireland (Kennedy & Fitzmaurice, 1972), the south-west of England (Holden & Williams, 1974) and in the Irish Sea (Kelley, 1979).

The pattern of paragnaths in Nereis diversicolor differs markedly between 17 populations from eastern and south-west England. There is a substantial heritable component to these differences, and there is no evidence that sediment type during development has any influence on them. Comparisons with previous studies reveal no consistent relationships of paragnath pattern with either sediment type or salinity. Evidence from scanning electron micrographs and correlations between different groups indicates that the anterior and posterior bands of paragnaths have rather different roles in feeding and suggest that the inter-population differences may be adaptations to different diets. The orientation of the jaws confirms that they play an important role only during predation and the handling of large particles, but not during the more usual browsing of the sediment surface.

Early development in the north-west Atlantic awning clam, Solemya velum (Solemyoida: Solemyidae) was examined by light and scanning electron microscopy. Embryonic and pericalymma larval stages, typical of protobranch bivalves, developed within individual adhesive gelatinous egg capsules and offspring emerged at hatching as benthic crawl-away juveniles. Fertilized eggs were light orange in colour, spherical, and had a yolk-mass diameter of approximately 190 μm. Entirely ciliated cylindrical pericalymma larvae, with a length and width of 318 μm and 208 μn, respectively, were obtained within 24 h. These larvae lacked an apical ciliary tuft, possessed nine rows of calymma cells, and actively rotated within the egg capsule. During metamorphosis, which occurred within 48 h of fertilization, the transitory larval ectoderm was entirely ingested. The prodissoconch measured roughly 320 μm in length by 215 μm in height. The foot and ciliated gill buds were well developed by four days after fertilization and subsequent growth contributed to the dissoconch or adult shell. Hatching began at 13 d after fertilization when the shell measured approximately 402 μm in length by 251 μm in height. Actively crawling and burrowing juveniles were cultured for six months after fertilization and an ontogenetic sequence of encapsulated and juvenile shell morphology was obtained for identification purposes. Current contradictory hypotheses regarding the phylogeny of marine bivalve develop-mental types are reviewed in light of new information on the Order Solemyoida.

Littorina obtusata is an epiphytic gastropod which lives for three to four years on its host Ascophyllum nodosum, a long-lived brown alga. Most of the population consists of adults, present throughout the year in the size range 14 to 17 mm. Newly hatched individuals appear between April and October with a peak in July; the immature winkles grow to merge with the adult cohort in May.

In contrast Littorina mariae is an annual; newly hatched individuals grow to maturity by the winter of their first year. Those reaching maturity overwinter as adults but very few live beyond spring of their second year. The population dynamics of L. mariae are closely linked with changes in the biomass of the alga Fucus serratus on which it lives.

The upper bathyal sea-pen Kophobelemnon stelliferum extends to depths of about 1600 m in the Porcupine Seabight, to the south-west of Ireland, but is rare below about 1150 m. Photographic data suggest that the species attains numerical abundances of more than 2 m−2and a wet weight biomass of at least 4 g m−2. The highest densities, however, do not necessarily correspond to the highest biomass values since there is a clear depth-related change in population structure. The largest sea-pens are restricted to the deeper parts of the bathymetric range of the species. There is also a marked change in the growth form at a total colony length of about 250 mm, with larger colonies having relatively more polyps than smaller ones. The sexes are separate in Kophobelemnon stelliferum and the sex ratio of colonies is about 1:1. The maximum oocyte diameter is about 800 μm, but there is no evidence of seasonal reproduction by this pennatulid in the Porcupine Seabight.

The swimming and buoyancy of the gelatinous pteropod, Cymbulia peroni, was observed and recorded on videotape from a submersible in the western Mediterranean. When not swimming Cymbulia peroni hangs neutrally buoyant, with its parapodia outstretched and motionless. Two modes of swimming were observed, slow swimming and rapid or ‘escape’ swimming. Slow swimming predominated, at speeds between 2 and 11 cm s−1. Most slow swimming was directed vertically up or down. Slow swimming is probably used for vertical migration and the avoidance of turbulence. Turbulence frequently occurs both at epipelagic and mesopelagic depths in the Mediterranean. Escape swimming was more rapid, and speeds up to 40 cm s−1 were measured. Differences between slow and escape swimming appear to be quantitative rather than qualitative, in contrast to other cymbuliids. Cymbulia peroni is an active and vigorous swimmer, clearly capable of vertical migration, and probably attains speeds greater than the highest measured in this study. Its behaviour in the field differs dramatically from its behaviour in the laboratory.

Deep-sea holothurians of the genus Paroriza (Family Synallactidae) have often been observed or photographed in pairs or triplets. Observations of tracks on the sea floor suggest that pairs may remain together for some time. We explored the reasons for pairing in a study of reproductive condition and diet, using animals collected by trawl from the bathyal and abyssal north-east Atlantic and by manned submersible from the bathyal slope of the Bahamas. Both species of Paroriza studied were found to be simultaneous hermaphrodites producing yolky oocytes. Oocytes of Paroriza pollens were about 350μm in diameter, whereas those of P. prouhoi were up to 450μm. Examination of oocyte size-frequency distributions suggests that reproduction is continuous for both species. Neither mean oocyte size, nor shape of the oocyte size-frequency distribution differed significantly between paired and unpaired P. pallens collected during the same season. These deposit-feeding holothurians appear to take food from the nutrient-rich phytodetrital layers on the surface of the sediment. Because their food resources are probably not patchy on small scales, the observed pairs are not likely to be feeding aggregations. We hypothesize that pairing increases the likelihood of external fertilization and that spawning in these species may be induced at any time by the presence of a conspecific rather than by seasonal cues.

Enypniastes eximia (Echinodermata: Holothuroidea) is a prominent member of the benthic boundary layer community in deep Caribbean waters. Like most holothurians it feeds on benthic sediments. Feeding is episodic and after collecting food on the bottom it returns to the water column at altitudes within about 50 m of the sea floor. Direct observations from submersibles and laboratory studies of living specimens have shown how bioluminescence is produced. Light production in E. eximia is triggered mechanically, and is produced by hundreds of granular bodies within the gelatinous integument of the animal. Local stimulation yields a localized response which gradually spreads to the entire surface of the animal. Broad impact yields a whole-body luminescent response. The integument of E. eximia is quite fragile, and strong physical contact readily causes the skin to be sloughed off in a glowing cloud. The degree of luminous response is a function of the severity of contact. In the laboratory the skin of E. eximia, along with its luminescent capability, regenerated rapidly. The anti-predatory role of bioluminescence in this species is apparently a ‘burglar alarm’ strategy. In the dark, near-bottom habitat, physical contact by a predator elicits light production which reveals the presence of the attacker to its own visually-cued predators.

Phagocytes of the starfishes Asterias rubens L., and Marthasterias ghcialis (L.) (Echinodermata: Asteroidea) phagocytose allogeneic and xenogeneic phagocytes in vivo, but form non-reactive aggregates or syncytia in vitro. The coelomocytes of the sea urchins Echinus esculentus (Mortensen) and Psammechimts miliaris (Gmelin), (Echinodermata: Echinoidea) also form aggregates or syncytia with allogeneic and xenogeneic cells in vitro. Mutual cy totoxicity could not be demonstrated either by enzyme-release or by decrease in numbers of viable cells in cultures of mixed origin as compared with autogeneic controls. The factors which may govern cell recognition and behaviour are discussed.

Kidney and spleen tissues from flounder Platichthys flesus (L.) collected from Neal Point in the estuary of the river Tamar were examined by x-ray microanalysis for the presence of heavy metals within the melanomacrophage centres. Ultrastructurally these centres consisted of groups of pigment-containing macrophages in which melanin was the most prominent pigment, but lipofuscin and haemosiderin were also present. Some of the macrophages also contained irregular metal particles and minerals with associated metals. The metals identified within these inclusions were Ti, Cr, Fe, Co, Ni, Cu, Zn, Sr, Ag, Sn, Ba, La, Ce, Nd, W, Au, Pb, Th and U. The results are discussed in relation to the sediment chemistry of the River Tamar, and the possible routes of uptake by the fish.

It has been argued by Johannesson & Johannesson (1990b) that the pattern of common genetic variation in Littorina saxatilis (Olivi) and Littorina neglecta Bean indicates gene flow in sympatric populations of these ‘species’. They suggest that L. neglecta is not a good species. We report that a gene diversity analysis of polymorphism in Aat-1 suggests that L. saxatilis and Littorina arcana Hannaford Ellis also show common features in allele frequency distribution. This casts doubt on the argument of Johannesson & Johannesson (1990b) from enzyme polymorphism data on Aat-1 that L. neglecta may simply be an ecotype of L. saxatilis. It seems likely that the similarities are due to operation of the same selection factors on all these species.

The pericardial gland of the deep-sea hydrothermal mussel Bathymodiolus thermophilus (Mollusca: Bivalvia: Mytilidae) differs from other mytilids by (1) a narrow lumen and (2) conspicuous polyhedral inclusion bodies in large cytoplasmic vacuoles of the epithelial cells. These inclusions do not contain metals as revealed by microanalysis but are possibly made of proteins. The cells of this gland exhibit a fenestrated basal border which indicates a site of haemolymph ultrafiltration. The kidney is histologically comparable to that of the coastal mussel Mytilus edulis.

The capture of the short-beaked garfish,Belone svetovidovi Collette & Parin 1970, off the Cornish coast is of particular interest in that it represents an easterly extension to the known range of this species in the eastern North Atlantic, and the first record in British waters.

In August 1990 seven garfish were angled, on mackerel bait, in Mount's Bay, Cornwall. The captor, Mr A.C. Cass, believing the garfish to be different from the common garfish,Belone belone (L.), sent the largest one to the laboratory of the Marine Biological Association for identification. The specimen was provisionally identified as the short-beaked garfish B. svetovidovi and later verified by one of us (A.W.). The other six specimens were not available for examination.

Garfish, sometimes called needlefishes, have elongated bodies. Both upper and lower jaws are long and beak-like, with sharp teeth. They are epipelagic, feeding near the surface and are often observed leaping and skittering over the surface of the water. Only two species are recorded in the genus Belone in the north-eastern Atlantic.Belone belone (including subspecies) is commonly found off the European Atlantic coast as far north as Trondheim, Norway. It is also found in the North Sea, the southern Baltic seas, the Mediterranean and Black Sea where it is commercially exploited (Collette & Parin, 1986).Belone svetovidovi has only recently been distinguished from B. belone, and consequently its abundance and distribution are less well known. It was first identified in northern European waters by Dorman (1984,1987) from southern Ireland.