A new mechanism of demosponge spicule formation was recognized during taxonomic studies of bioeroding sponges (Porifera: Demospongiae: Clionidae). To date different spicule types have been explained by matching structures to their organic matrix, the axial thread. Bulbous structures, however, do not have an organic counterpart. Immature spicules of Cliona tinctoria and Pione caesia have irregular, rough heads. Higher magnification during scanning electron microscopy shows that silica granules are deposited regionally to form bulbs. Later silica secretion smoothens the bulb surface. Silica deposition in form of granules rather than in layers appears to be a structuring tool in tylostyles.

The reflecting layers in the external surfaces of salmon were studied during smoltification by making direct observations on the reflecting structures. The relationships between the reflecting layers in the epithelium external to the scales, in the tissues of the scales, and in the skin internal to the scales are given. Some fish, including fish blinded by pseudobranchectomy were reared under very abnormal lighting conditions and the processes of silvering and regeneration of scales followed on them. It was found that the pattern of silvering in smoltification and regeneration was not at all affected by lighting and that, although regenerated scales can easily be distinguished in other ways from those they replace, the orientations and reflectivities of their plate-lets are, with occasional exceptions, almost indistinguishable from those they replace.

Ceratothoa collaris is reported for the first time outside its known geographical range, which was restricted to north-western African coasts (from Senegal to Tunisia). Many specimens of different developmental stages were collected off the Lebanese coast in the eastern Mediterranean. In addition to an update of the geographical range, synonymy and host specificity, an accurate redescription of the species is given on the basis of new and old materials.

Freezing-point measurements were made of blood samples taken from specimens of the marine wood-boring isopod Limnoria that had been exposed to sea water of various salinities for 2-3 days. Most of the work was done with L. (L.) tripunctata Menzies, but some preliminary experiements were carried out with L. (L.) lignorum (Rathke) and L. (L.) quadripunctata Holthuis.

It was found that the freezing point of the blood averaged 0·17°C above that of the external of medium in both hyp- and hyperosmotic environments. In the absence of any obvious factor which could explain this discrepancy, it is assumed that Limnoria has a certain degree of control over its blood concentrations.

Further experiments showed that the blood concentration fell as soon as the animal was introduced to the reduced salinity and levelled off at the hyperosmotic value within a few hours. There was some evidence of a periodicity in the osmoregulation.

The possible energetics of osmoregulation in Limnoria are discussed and it is concluded that the amount of energy utilized in the process is unlikely to make any significant inroad into the energy resources available for boring activity.

Gold has been determined in six marine sponges by neutron activation analysis. The amounts found (1·8–12·6 × 10−8 g/g dry sponge) are higher than would be expected from measurements of the distribution of 198Au between sea-water and dead sponge samples.

Many attempts have been made to devise methods for concentrating gold from sea water, but none of them are commercially viable. Recent work has shown that gold can be concentrated by adsorption or absorption on certain artificial polymers (Hummel, 1957; Bowen, unpublished). This note describes some measurements of the accumulation of gold by marine sponges whose scleroprotein structure resembles some of the artificial polymers employed.

Sponges are rare in extreme environments, and very little is known about their adaptations to such settings. Evidence from two species in a marine-derived midwater stratified crater lake on Satonda Island (Sumbawa, Indonesia) suggests their production of gemmules (resting bodies), a rare trait in marine sponges but common in freshwater forms, may be a survival mechanism in the lake's harsh environment. With its epilimnion hydrochemistry—characterized by changing alkalinity, salinity, and O2 levels over the region's wet and dry seasons—the lake sustains only a few marine macroscopic organisms, among them the suberitid sponges Protosuberites lacustris comb. nov. and Suberites sp. (Hadromerida: Suberitida). Both species belong to the same group as sponges reported from other marine-derived lakes with strongly varying and extreme environmental (especially chemical) parameters. The morphological characters, taxonomic position, ecological adaptations, environmental conditions, and biota associated with the sponges in this ecologically unique site are presented here.

Many brachyuran megalopae swim with the legs disposed in a curious manner. The chelipeds and first two pairs of walking legs are folded tightly beneath the body, while the two posterior pairs are wrapped over the dorsum, the third pair being stretched out anteriorly, the dactylus, according to its length, touching or being looped round the eye-stalk. It is suggested that this posture gives stream-lining to the megalopa and improves its swimming. The described arrangement has been observed in all but three of some twenty-five species occurring at Plymouth.

In the three exceptions, Corystes cassivelaunus, Thia polita and Pinnotheres pinnotheres (= veterum), all legs are carried folded beneath the body.

Reference is made to previous descriptions of the folding of the legs in the brachyuran megalopa.

Aora spinicornis Afonso is recorded for the first time from the British Isles. Two species of Aora, A. gracilis (Bate) and A. spinicornis Afonso are now known from these waters. A. typica Krøyer, long considered a British and Irish species, is actually known only from the Southern Hemisphere. Figures and diagnoses of both species are provided together with a key to their identification.

Introduction

Lincoln (1979) records one species of Aora Kreyer from British and Irish waters. Due to an oversight (Lincoln, personal communication) he overlooked the paper by Myers (1973) (although listed in the bibliography) and attributed the single species to A. typica Krøyer, a species actually known only from the Southern Ocean between 20° S and 50° S (see Myers & Moore, 1983 which also includes a key to the world species). Two species of Aora are now known from the British Isles: A gracilis (Bate) which is widely distributed, and A. spinicornis Afonso, recently discovered in Lough Hyne, Co. Cork, and herein reported for the first time from these waters. This latter species has a Lusitanian distribution (Azores, Canaries, Mediterranean) and may occur in south-western England and Wales, but has been confused previously with A.gracilis (Bate). Both species have been described and figured by Myers (1973, 1982) and do not require further detailed analysis. However, since both species are now known to occur in these waters and are not both treated by Lincoln's widely used monograph, the two species are figured here as entire specimens (for details of appendages including mouthparts see Myers, 1982) and briefly diagnosed, and a key is provided to facilitate their identification by British and Irish workers.

In a former paper (Allen, Phil. Trans. Roy. Soc. B., Vol. 211, p. 131, 1921) it was shown that the Syllid Procerastea Halleziana Malaquin, addition to the ordinary mode of sexual reproduction which occurs in this group, reproduced asexually by a process of fragmentation, followed by the regeneration by each fragment of a new head and series of anterior segments and of a new pygidium and posterior segments. The fragments usually consisted of sections of two, three, or four segments each, in the region of the body behind the seventh setigerous segment. It was further shown that this breaking up of Procerastea, which could be produced artificially at any time by treating the worms with sea-water of low salinity, made by adding distilled water to natural sea-water, took place according to a definite law. The first section consisted normally of the head and setigerous segments 1 to 7, then followed three sections of two segments each (Segments 8 and 9; 10 and 11; 12 and 13), then three sections of three segments (14–16; 17–19; 20–22), followed by four or five sections of four segments each, and then a number of sections of three segments.

The diet of the monkfish Lophius gastrophysus is described based on the analysis of stomach contents, for the south-western Atlantic from samples landed in the fishing port of Niteroi, Rio de Janeiro state, Brazil, from April 2004 to March 2006. Feeding intensity, measured as the presence or absence of contents in stomachs, and differences in the items' composition were analysed by sex, size-class and season. High feeding intensity predominated for females >32 cm and for males <31 cm. There was no seasonal pattern in the occurrence of full or empty stomachs. The most important category in the diet was fish with 25 identified species. Dactylopterus volitans showed the highest alimentary index value, mainly because of the feeding of juvenile monkfish. The second most important category was Mollusca, represented mainly by squid. No relationships between predator- and prey-lengths and weights were observed; but there was a tendency to consume light and small prey independently of the size of the monkfish.

The calanoid copepod Temora longiornis (Müller) has sub-cuticular secretory glands located on both the body and swimming legs. The glands are tri-cellular, consisting of a secretory cell (producing a proteinaceous secretion) opening through a cuticular pore, a collar cell surrounding the neck of the secretory cell, and a duct cell which lines the pore opening. The possible function of the secretion is discussed.

Submarine cliffs are typically crowded with sessile organisms, most of which are ultimately exported downwards. Here we report a 24 month study of benthic fauna dropping from such cliffs at sites of differing cliff angle and flow rates at Lough Hyne Marine Nature Reserve, Co. Cork, Ireland. The magnitude of ‘fall out’ material collected in capture nets was highly seasonal and composed of sessile and mobile elements. Sponges, ascidians, cnidarians, polychaetes, bryozoans and barnacles dominated the sessile forms. The remainder (mobile fauna) were scavengers and predators such as asteroid echinoderms, gastropod molluscs and malacostracan crustaceans. These were probably migrants targeting fallen sessile organisms. ‘Fall out’ material (including mobile forms) increased between May and August in both years. This increase in ‘fall out’ material was correlated with wrasse abundance at the cliffs (with a one month lag period). The activities of the wrasse on the cliffs (feeding, nest building and territory defence) were considered responsible for the majority of ‘fall out’ material, with natural mortality and the activity of other large mobile organisms (e.g. crustaceans) also being implicated. Current flow rate and cliff profile were important in amount of ‘fall out’ material collected. In low current situations export of fallen material was vertical, while both horizontal and vertical export was associated with moderate to high current environments. Higher ‘fall out’ was associated with overhanging than vertical cliff surfaces. The ‘fall out’ of marine organisms in low current situations is likely to provide an important source of nutrition in close proximity to the cliff, in an otherwise impoverished soft sediment habitat. However, in high current areas material will be exported some distance from the source, with final settlement again occurring in soft sediment habitats (as current speed decreases).

As well as acting as a neurotransmitter, serotonin is also involved in morphogenetic signalling during crucial phases of many developmental and regenerative processes such as cleavage, migration and differentiation. Echinoderms display nerve-dependent regenerative phenomena and serotonin is one of the main neural regulatory factors that have been identified in them. The present work was designed to investigate the broad-spectrum involvement of this molecule in echinoderm regeneration, focusing on arm regeneration in the crinoid Antedon mediterranea. We carried out specific in vivo exposure experiments to selected anti-serotonergic drugs (a synthesis inhibitor: parachlorophenylalanine and a receptor antagonist: methiothepin) and explored their possible effects on arm regeneration. Drug exposure appeared to affect regeneration, causing a general delay of regenerative growth and several histological anomalies mainly in the muscles of the stump. In addition, exposure to the antagonist produced a marked reduction of cell proliferation in both the regenerate and the stump. Our results provide further evidence that serotonin has wider functions than those related to interneuronal communication and that it may be a critical signalling molecule in the main processes of regeneration such as proliferation, morphogenesis and differentiation.

An objection often raised to experiments on tissues treated with artificial solutions and isolated from nervous control is that results obtained under such highly abnormal conditions can be of no real value. This criticism arises essentially from a misconception as to the aim of the experiments in question, but it is encountered so frequently that it may not be out of place to consider briefly why it is necessary for the physiologist who would learn something of the more intimate mechanism of the cell to work with tissues under artificial conditions.

Tributyltin (TBT) leaching from the antifouling paint on hulls of pleasure craft eliminated a population of dog-whelks Nucella lapillus from Watermouth Cove in the Bristol Channel but outside the Cove the number of snails was apparently unaffected. Following the ban on TBT in antifouling paints, the species has recovered most of its former range in the Cove. It is postulated that the recolonization was from a subtidal population of unusually large and elongated individuals. It was observed that it had taken some 13 years to recolonize a distance of 30 metres.

The measurements recorded for marine algæ of various groups show that the reaction of the sap is in most cases almost neutral, and in no case is the sap of the pronounced acid character met with in many land plants. This being so it follows that the enzymes concerned in the metabolism of these algæ must be quite different from those which effect corresponding changes in land plants, as may be seen on referring to the optimum pH values for various enzymes quoted in the writer's previous paper on the reaction of plant cells (1922).

Some marine endolithic algae grow well and are restricted to the strongly lit littoral and uppermost sublittoral environments. The wide depth ranging boring algae must however adapt to different light intensities. Whereas Eugomontia sacculata Kornmann is considered as a form adapted to high light intensity (Akpan, 1981), Ostreobium quekettii Bornet & Flahault and Conchocelis - a boring phase in the life cycle of red algae in the Porphyra and Bangia genera - are able to survive under low light conditions even though they thrive at depths with strong illuminations (Rooney & Perkins, 1972; Clokie & Boney, 1980). Sheath, Hellebust & Sawa (1977) have demonstrated that the Conchocelis of a Porphyra sp. can survive prolonged very dim light condition and probably remain in a ‘steady state’ without growth in the dark for a long time. This adaptation is important for those algae in the lower part of the photic zone because during winter, deep light penetration is hampered.

A new species of the family Tritoniidae is described from the tropical South Atlantic Ocean. The animal was found off north-east Brazil. Tritonia khaleesi sp. nov. is up to 12 mm long, with a slender white body, of which the notum is covered with one broad white band extending from between the eyes and veil to the tail; veil with 4 velar appendages; retractable white rhinophores; rhinophoral sheath with fleshy extension; seven pairs of branchial plumes; the anus is located between the 3rd and 4th gills on the right side, and the genital opening is under the 2nd gill. Internally, T. khaleesi sp. nov. is distinguished from other tritoniids by jaws with 10–14 rows of denticles on the inner lips, absence of stomach plates and the radular formula 32 × 2–5.1.1.1.2–5 teeth. Tritonia khaleesi sp. nov. is the only Tritonia that possesses a unicuspid rachidian tooth as an adult.

Many size-selective predators switch their diet during ontogeny. At the White Sea, the adult moonsnails Amauropsis islandica feed mostly on Macoma balthica clams. The diet of juveniles was largely unknown. We conducted a field survey and a caging experiment to find out if juvenile moonsnails can prey on Hydrobia ulvae, and whether they prefer this snail to their usual prey. Live molluscs and their intact or perforated shells were collected from 34 sediment cores. We exposed the single-prey cages with 50 Macoma (MP) or 50 Hydrobia (HP) together with five Amauropsis juveniles, as well as the cages where both prey species were in a 25:25 proportion (HMP). While live Hydrobia was more abundant in the natural assemblages, Amauropsis preferred Macoma, as indicated by proportions of perforated shells. The caging experiment produced similar results. Per capita Macoma consumption rate was significantly higher than Hydrobia consumption rate (6.4 ± 0.5 mg day−1 ind.−1vs. 1.4±0.2 mg day−1 ind.−1 in MP and HP respectively). Prey consumption rates in the single-prey treatments were higher than in mixed-prey cages regardless of prey species. Different mechanisms explain this variation: for Hydrobia it is a consequence of the dietary shift, while for Macoma it reflects the ‘floor’ effect in HMP cages, where virtually all Macoma had been drilled by the end of exposure term. While Macoma is the preferable prey of young Amauropsis, Hydrobia can supplement the diet of juveniles when Macoma is scarce in certain locations.

Wounds caused by predation and/or physical disturbances to sessile marine animals are common. Consequently, these organisms had to develop strategies to endure such injuries and survive in such a dynamic environment. Sponges are known to possess one of the greatest capacities of regeneration among living metazoans, but this feature has been largely studied only in Demospongiae. In Calcarea, very few species have been investigated. Hence, we analysed the regeneration and speed rates from two regions (osculum and choanosome) of the body of a calcareous sponge: Ernstia sp. Only the osculum regenerated until the end of the experiment, while the choanosome simply cicatrized. Calcareous sponges seem to have a polarized regeneration closely related to their external morphology and level of individuality and integration. A brief review of the regeneration capacity in Calcarea is presented.