Vital staining with Janus Green, phase contrast and scanning electron microscopy were used to map the distribution of free neuromast organs from first hatching, 10 mm long larvae to 100 mm long juveniles of herring (Clupea harengus L.), with some further observations on juvenile sprat (Sprattus sprattus (L.)). Neuromasts are sparsely distributed on the head and trunk at hatching but soon proliferate on the trunk where, by a length of 13–15 mm, they occur one to every segment. Near metamorphosis there are at least three rows of neuromasts on the anterior trunk region, 6–9 single neuromasts on the caudal fin and as many as 50 on the head. The scales develop at about 40–50 mm and the neuromasts are then found singly or in groups of 2 or 3 on the surface of the scales of the anterior trunk.

The lateral line develops at 22–24 mm and appears to incorporate existing free neuromasts on the side of the head. Unlike the cupulae of the free neuromasts, which are cylindrical, the lateral-line cupulae are thin erect plates lying along the axis of the canals. They are probably continually growing and being shed, followed by renewed growth.

All neuromasts contain hair cells of opposing polarities; most free neuromasts are arranged with these polarities arranged fore-and-aft, but a few are dorsoventral.

Measurements were made of the strength of temporary attachment of the cypris larvae of Balanus balanoides using a sensitive micro-balance. The strength of adhesion on arthropodin treated slate panels exceeded that on clean panels and the measured forces increased as the season progressed. The observed maximum cyprid attachment strength reached 3·8 × 105 N m−2, considerably less than the bond strength of a commercial epoxy adhesive (107 N m−2) but of the same order as the force required to remove limpets (Patella) from a slate substrate. The results are discussed in the context of substrate recognition by barnacle cyprids and the possible mechanisms of adhesion involved.

Profound cyclical changes were observed in the epidermal thickness and in the concentrations of goblet cells and epidermal melanophores in an inshore population of winter flounder, Pseudopleuronectes americanus Walbaum. There is sexual dimorphism which is particularly prominent in the thickness of the epidermis during the pre-spawning period in the spring. At this time the male develops a significantly thicker lower epidermis. During and shortly after the spawning period (lower skin), or somewhat earlier (upper skin), there is a significant thinning of the epidermis in both sexes. Significant increases occur in goblet cell frequency, those of females being greater than males, during autumn and early winter and the April/May pre-spawning period. Goblet cell frequencies decrease in mid-winter (January–March) when general activity is low, and in the thin summer epidermis. These observations are compared with data from other teleosts and discussed in relation to hormones possibly affecting the epidermal structure of teleosts and in relation to known hormonal cycles in winter flounder.

The analysis under a scanning electron microscope of young larval and postlarval shells of Mytilus edulis and Margaritifera margaritifera reveals some primitive characters. Among these features, the most important are the ligamental formations which are described in detail during ontogenesis. In M. edulis a primitive ligament appears in a pit under the cardinal plateau immediately following metamorphosis. A second ligament later develops on the posterior edge of the shell, and becomes the only ligament present in the adult. In M. margaritifera a provisional internal structure acts as a ligament in the young glochidia fish parasites. A definitive external ligament only develops following metamorphosis of the glochidia.

The similar pattern of development of these ligaments in both species may represent the development of the ligament in the first bivalves.

The results of detailed sterol analyses on the livers of seven species of sharks are presented. The sharks appear to have a very specific requirement for cholesterol as their sole component sterol (> 99 % total sterols), which several species of bony fish do not. In fact, from their sterol composition, sharks appear more similar to terrestrial vertebrate classes than bony fish. If, as has been suggested, sterol composition is a measure of evolutionary advancement, then this work presents biochemical evidence that sharks are not as primitive as has sometimes been assumed.

Suspension-feeding in the holothurian Neopentadactyla mixta (Östergren), 1898 is accomplished by an adhesive secretion synthesized in modified retractable discs of epithelial cells located on the terminal tentacular nodes. Besides secretory cells, each disc epithelium is composed of three other cell types: ciliated, granular and nerve cells. The fine structure and possible functions of the epithelium are described with reference to the behaviour of tentacles during feeding and the observations are compared with existing information on holothuroid feeding mechanisms.

Analyses of the cirratulid polychaete Tharyx marioni have shown that this species contains a high concentration of arsenic, its whole-body concentration usually exceeding 2000 μg/g dry weight, even when living under low ambient arsenic conditions. Similar levels of arsenic are present in both juvenile and adult worms. Other cirratulid species, such as Cirriformia tentaculata and Caulleriella caputesocis, from the same habitat contain low arsenic concentrations (< 100 μg/g dry weight).

Much of the arsenic in T. marioni (ca. 20 %) is contained in the palps which comprise about 4% of the body dry weight; in these organs, concentrations of 6000–13 000 μg/g dry weight have been measured. Some of the arsenic in the palps is bound with copper in granules but the bulk appears to be organically associated; extraction data indicate about 65% of the total arsenic is linked to the lipid pool with a further 25% being proteinbound arsenite (cysteine-extractable). The results of experiments using 74As suggest that most of the arsenic is derived from the sediments rather than the water but the mechanisms and functions of this arsenic accumulation by T. marioni remain to be investigated.

Preliminary determinations of heavy metals in winkles Littorina littorea along a concentration gradient in the Fal Estuary suggested that whole body concentrations might be related to those of the water. When animals were transplanted to this heavily contaminated estuary, changes in tissue concentrations of As, Co, Cu and Zn were largely complete after 2 months.

Relations between the winkle and water concentrations may be indirect since its algal diet is thought to be the main source for most heavy metals. Data from a large number of United Kingdom estuaries were used to compare concentrations of 12 metals in L. littorea with those of the brown seaweed Fucus vesiculosus which forms part of its diet. Very significant relations were found for Ag, As, Cd and Pb, suggesting that since concentrations in the seaweed probably reflect those of the surrounding water, so also do those of the winkle. However, concentrations of Ag in the animal also appeared to be influenced by dietary Cu levels. In addition, significant relations between the two species were found for Cu, Fe, Hg and Zn, but the slopes were shallow, perhaps indicating regulation by the winkle. For Cr and Mn relations were not very significant and, for Co and Ni, concentrations in the winkle appeared to be influenced by those of Cu and Zn.

Compared with concentrations in L. littorea, those of L. littoralis from the same site were generally higher whilst in L. saxatilis they were usually of the same order or lower.

In assessing the winkle as an indicator of metal contamination the present results have been combined with those of other workers to produce comparisons between most estuaries in England and Wales. It is concluded that whilst the winkle is a useful indicator for Cd and a few other metals, it is certainly not a perfect indicator organism.

A new species of Listriella is described and figured from maerl deposits in Kilkieran Bay, Co. Galway. The holotype of the only other British species is figured for comparison. The amphipod fauna of Kilkieran Bay (Co. Galway) maerl is compared with that of Eddystone shell gravels.

Various neurotransmitters were injected into the blood supplying the brain of Octopus vulgaris and the effects, particularly on the chromatophores, were observed. l-glutamate, GABA, dopamine, noradrenaline and octopamine caused expansion of the chromatophores and darkening of the skin; ACh caused retraction of the chromatophores and paling; 5HT caused differential expansion and retraction: mottling. These responses, which are neurally mediated, were particularly well defined for ACh and 5HT and the effects of these drugs were studied in more detail. The paling effect of ACh was mimicked by nicotine but not muscarine and was partially antagonized by tubocurarine. The mottling induced by 5HT was transiently antagonized by methysergide maleate, as was ink-ejection and defaecation. Brain lesions to localize the sites of action of ACh and 5HT suggest that they act at the level of the sub-oesophageal lobes to control the chromatophores, but that 5 HT may act at the level of the optic lobe to control inking and defaecation. These results are related to the pharmacology and histochemistry of the cephalopod brain and to the organization of the chromatophore control system.

The development of the persistent suture tag has permitted the study of long-term migrations of large decapods like the European edible crab (Cancer pagurus L.). A tagging study of the growth and migrations of C. pagurus was part of a research project undertaken to provide advice on the effective management of the English Channel crab fishery. During the years 1968–74 a total of 15296 suture-tagged crabs was released; the majority in the main fishery off south Devon and Cornwall, but releases were also made in the eastern half of the Channel. The early releases were mainly inshore, within 22 km (12 nautical miles), but as the fishery expanded offshore releases were made in mid-Channel.

Most of the recaptures occurred within two years of release, with the highest recapture rates being in the most intensively fished areas during the main fishing season. From the total of 2714 crabs recaptured, 2255 had reliable recapture information. In the inshore release areas 90 % of the males and 76 % of the females were recaptured within 18 km (10 nautical miles) of their release position. Offshore the corresponding proportions were considerably lower at 76 % and 59%, with 11 % of the males and 21 % of the females having moved > 90 km (49 nautical miles).

When males did move > 18 km they were mainly the larger males and their mean displacements were 14–31 km in several directions. The offshore releases of males in the middle and eastern Channel showed more extensive movements, which appeared to be directed, most of them being in a westerly direction, with mean displacements of 41–114 km. With only one exception, the female inshore releases had a mean direction of movement of between south and west, with mean displacements of 12–84 km. Overall, those females making the more extensive movements were larger than those caught in the vicinity of the release positions. The last inshore release at Portland Bill gave the first indication of extensive westerly movements from the eastern part of the English Channel.

Movements of females released on the offshore Devon and Cornwall grounds were mainly in a westwards direction, although several inshore movements and longer distance movements of up to 302 km towards the French coast were recorded. The recaptured females from the middle and eastern Channel releases showed greater mean displacements (110–158 km), all in a westerly direction. Only 10% of the mid-Channel recaptures were made within 18 km, with 73% being caught > 90 km from their release position. The highest mean velocity was 23 km/week, with an individual maximum of 183 km/week.

Most of the recaptures of male C. pagurus released inshore were made near the release position, and those movements which were observed would appear to be the result of nomadism. Offshore males seemed to be more mobile, but a nomadic existence for larger male C. pagurus seems more likely than migration. Female C. pagurus in the English Channel are more mobile than males. Large, mature, female crabs leave the eastern Channel and congregate in the autumn off south Devon. During the winter and spring there may be some nomadic movements. These migratory movements are reflected in the size composition and sex ratio. The migrations seem to be related to the breeding behaviour, ensuring a suitable sea-bed substrate for berried crabs and/or allowing distribution of the larval phase on the easterly residual currents in the English Channel.

From works on the anatomy and ecology of dorid nudibranchs it has been assumed that they were capable of cutaneous respiration through their dorsal mantle. The present work has shown how the oxygen uptake is depressed when the dorids Onchidoris bilamellata and Archidoris pseudoargus are exposed to air and the gills collapsed into the body surface. The effect of ligaturing the gills of A. pseudoargus into the branchial pocket has enabled direct measurements to be made of the mantle respiration.

The effect of temperature on respiration was examined.

A humoral immune response was elicited in adult dogfish by intramuscular injection of keyhole limpet haemocyanin (KLH). The antibody raised to this antigen was measured by an agglutination technique. The antibody-containing fraction of the serum was isolated in a two-step procedure utilizing gel nitration on Sepharose 6B and slab gel electrophoresis. A rabbit antiserum was then raised to the purified immunoglobulin. Further gel filtration studies revealed that the anti-KLH agglutinating activity was restricted to a highmolecular-weight serum fraction (approximately 800000) in fish immunized for up to 18 months. No anti-KLH precipitating activity was detected in fish at any stage of immunization; however immunodiffusion studies with the rabbit antiserum raised against dogfish antibody confirmed the existence of an 800000 molecular weight form and also a lighter species weighing 160000 daltons in both normal and immunized fish. The antigenic specificity of this latter molecule was not demonstrated. Immunoelectrophoretic analysis of the antibody revealed a neutral/slight anodic mobility, and after reduction and alkylation the presence of two polypeptide chains weighing 18200 and 75 860 daltons was demonstrated by thin-layer gel chromatography. These physicochemical characteristics make dogfish antibody analogous to mammalian immunoglobulin M (IgM).

Of a wide range of algae tested, juvenile Convoluta roscoffensis ingested only Platymonas convolutae, the natural symbiont; related species of the genera Platymonas, Prasinocladus and Tetraselmis; and Chlamydomonas coccoides. Platymonas convolutae was not ingested to a greater extent than Prasinocladus marinus, Tetraselmis tetrathele and Tetraselmis verrucosa, or taken up in preference to T. verrucosa when animals were exposed to a choice between the two species. Convoluta ingested fewer cells of C. coccoides than P. convolutae and related species. Uptake of P. convolutae was not affected by pretreatment of the cells with lectins or proteases, incubation in media of pH 5·0–9·0 or inhibition of algal photosynthesis, but was substantially reduced if the algae were killed.

Cells of P. convolutae, Pr. marinus, T. tetrathele and T. verrucosa persisted and divided in juvenile Convoluta. The algal population in the worms started to increase 2–3 d after ingestion and within 15–20 d the animals were uniformly green. These algae formed a viable symbiosis with Convoluta and promoted the growth of the animals. In contrast, C. coccoides cells did not persist in Convoluta for more than 12–24 h a nd were probably disrupted.

P. convolutae cells lost their thecae within a few days of ingestion and before migration from the central to sub-epidermal region of the animal. Animal vacuoles surrounded recently ingested thecate algae. Structural studies of the adult symbiosis suggest that the algae were also intracellular and enclosed in vacuoles.

It is proposed that Convoluta discriminates against algae unrelated to P. convolutae on initial contact and in the central region of the host. The nature of the recognition mechanism(s) has not been established.

Uric acid is an excellent nitrogen source for the growth of cultures of Platymonas convolutae, the symbiotic alga from Convoluta roscoffensis, and related Platymonas and Tetraselmis species. Nitrate-grown cells of P. convolutae and T. tetrathele have two uptake systems for uric acid, which conform to Michaelis–Menten kinetics; a high-affinity system operating in the concentration range 0·2–4·5 μM a nd a low-affinity system operating at higher concentrations of uric acid. Uric acid uptake by P. convolutae is abolished by uncouplers of phosphorylation. In darkness, intact cells of P. convolutae metabolize [2-14C]uric acid to [14C]carbon dioxide. These results are consistent with the proposal that the algal symbionts of C. roscoffensis utilize uric acid, received from the host, as a nitrogen source.

Aposymbiotic juvenile and symbiotic adult C. roscoffensis under standard culture conditions contain uric acid. The solid uric acid content of juveniles declines on establishment of symbiosis with P. convolutae and the endogenous uric acid is utilized in the adult symbiosis under conditions of nitrogen demand. However, adult C. roscoffensis do not utilize exogenous uric acid. The growth of adult but not juvenile C. roscoffensis is dependent on nitrogen enrichment of the medium, and it is proposed that uric acid utilization is of significance to the growth of the developing symbiosis in a nitrogen-poor environment.

Species of the cyclopoid copepod genus Oncaea are commonly polymorphic. Using material from several localities, forms of O. venusta Philippi, O. mediterranea Claus and O. conifer a Giesbrecht are described, and specimens of two closely related and morphologically similar species, O. ornata Giesbrecht and O. englishi Heron, are compared. The integumental pore signature patterns of all these species are mapped from stained, tissue-free integuments. Each species has its own characteristic pore signature pattern and sexual dimorphism is confined to the urosomal pore pattern. Similarly the prosomal pore patterns of female copepodid 5 do not usually differ from those of adult females, but urosomal patterns are distinct. Juveniles of O. conifera are exceptional in this respect; their prosomal pore pattern lacks the detail of the adult pattern. Differences in the pore signatures of O. ornata and O. englishi confirm their status as separate species. Signatures in the O. conifera ‘group’ may also prove to be distinct. Whereas intraspecific variation in pore signatures may exist at a level below the resolution of this technique, such small morphological differences should be considered to be taxonomically insignificant.

The implications of polymorphism in the process of speciation, and the mechanisms by which the polymorphic forms are maintained are discussed.

Scanning electron microscopy and light microscopy are used to examine the morphology of pores and their associated sensilla. Three types of sensilla are described, peg, short-hair and long-hair sensilla.

The life-history of hydroids from a mixed population of Tubularia indivisa and ‘T. ceratogyne’, from an intertidal site at Felixstowe, Suffolk, has been studied. Tubularia breed throughout the year, but recruitment is greatest in spring with a smaller peak in late summer. The spring-recruited hydroids are the progeny of T. indivisa, but during the summer they mature as ‘T. ceratogyne’ and breed to produce the T. indivisa that dominate the population in spring. It is concluded, on this evidence, that ‘T. ceratogyne’ is a form of T. indivisa.

In this population T. indivisa suffers from predation by the nudibranch Dendronotus frondosus, and their mortality rate varies from 2% per month in winter to 70% per month in summer. The life-span of T. indivisa is approximately one year, but their mean post-larval life expectancy varies from 30 days (spring recruitment) to 160 days (autumn recruitment). There is no evidence that autotomy of the hydranth is an integral part of the life of T. indivisa.

The ‘strength’ of the endogenous locomotor activity rhythm of four peracarid crustacean species, denned by the precision and persistence of the rhythm, was examined with particular reference to a ‘burrowing’ versus epifaunal supralittoral life-style. The ‘strength’ of the endogenous component of the activity rhythm was also illustrated using a modified periodogram analysis. In all species, the talitrid amphipods Talitrus saltator, Talorchestia deshayesi, Orchestra gammarella and the oniscoid isopod Ligia oceanica, the laboratory-monitored rhythm and the field emergence pattern displayed a nocturnal, circadian pattern with no clear evidence of any circa-tidal influence. The precision and particularly the persistence of the rhythm of the sand-shore burrowing species T. saltator and T. deshayesi are especially well developed, although a ‘strong’ endogenous component is present in the rhythm of all four species. The significance of the endogenous locomotor rhythms is considered with respect to the supralittoral ecology of the species.