The escal light gland of three different-sized specimens of the deep-sea anglerfish Haplophryne mollis (family Linophrynidae) has been examined by light and electron microscopy. The light gland has a central cavity, with diverging branched ducts which ramify into numerous tightly-packed radial tubules. In the two largest specimens all glandular lumina contain symbiotic bacteria. Except for a thin-walled part of the typical radiating tubules, the epithelial walls of the light gland are of a uniform structure, consisting of flattened basal cells, situated next to the basal lamina, and tall cells extending to the lumen.

In the smallest specimen examined the various parts of the light gland were not fully differentiated and only a very few symbiotic bacteria were present; its glandular epithelium differed from that of the two larger specimens by containing many goblet cells, the secretion of which may be important for the initial establishment of the right strain of symbiotic bacteria

Observations on the luminescence of live specimens have shown that the light emission can be rapidly modulated from within the esca. The in vivo flash kinetics are considerably slower than those of Dolopichthys longicornis, but similar to those of both the caruncle exudate of Ceratias holboelli and in vitro anglerfish bacterial luciferase.

A spermatophore is defined as a capsule of albuminous matter containing a number of sperm. Among opisthobranchs the families Retusidae, Philinoglossidae, Bullidae, Atydae and Runcinidae are all said to possess a copulatory apparatus which stores sperm and also forms spermatophores (Ghiselin, 1966). Relatively little information exists concerning the structure of the copulatory apparatus or the spermatophore in these groups and practically nothing is known about the copulatory behaviour of the animals and the fate of the spermatophore (Perrier & Fischer, 1914; Ghiselin, 1963, 1966; Thompson, 1976;Beeman, 1977). This paper will focus on the structure of the spermatophore of the cephalaspid Runcina (Kress, 1977). The formation of sperm occurs in the hermaphroditic glands, in a more central position than that of the eggs. These autosperm leave via the common genital aperture which is located laterally to the gills. They travel by means of strong ciliary action, through a seminal groove to the male copulatory apparatus on the right of the mouth. The sperm then moves through the penis and the prostate into a storage sac, the seminal vesicle. For copulation, these sperm are packed into a spermatophore which should presumably be introduced into the common genital aperture but which may be found attached to the mantle or foot, even to animals not yet sexually mature. We have taken this opportunity to study the spermatophore which otherwise might not be easily detected.

The first record of the plexaurid genus Psammogorgia from the shallow waters of Peru is reported here. A new species (Psammogorgia hookeri sp. nov.) is described from Isla San Gallán, Paracas National Reserve. The new species was morphologically analysed using light microscopy and scanning electron microscopy. It is distinguished from the others in the genus by its small size; prominent calyces with wide lips around polyp apertures and without a special type of sclerites, but with a concentration of irregular, thorny spindles and wart-clubs around the calyx rim; coenenchymal sclerites that do not reach more than 0.2 mm long; the occurrence of conspicuous star-like radiates; and the colour of the colony and coenenchymal sclerites, which is coral red. The results increase species richness within a genus that has not been studied for more than a century, and contribute to the establishment of characters for further morphological studies. Additionally, the new species adds value to existing protected areas and to the octocoral biodiversity records for the Peruvian region and the eastern Pacific.

It has long been known that there is a considerable seal population on the North Cornwall coast. But precise information concerning the species present, the density of the population, and the positions of the rookeries has been almost entirely lacking. In order to obtain data on these points, a detailed survey of the North Cornwall coast was carried out during the fortnight August 7th-20th (1935) inclusive.

The small acoele Convoluta roscoffensis Graff occurs locally in abundance in suitable intertidalareas of wet sand from the Channel Islands and the coast of Brittany southwards along the westcoast of France (Holligan and Gooday, 1975). The species is well known for its uniquely intimate symbiosis with Platymonas convolutae Parke et Manton: after initial ingestion of the living alga by hatching ‘ white’ worms the animal comes to depend entirely on the algal cells contained in its tissues for its nutrition (Holligan and Gooday, 1975).

The antero-lateral margins of the carapace in many of the crabs of our own and of foreign coasts are beset with a row of teeth or spines, which vary in character and number in different species and genera. In the Oxyrhyncha (Spider-crabs) the whole surface of the carapace is generally studded with spines and stiff hairs of a peculiar character, but there is no general restriction of these processes of the carapace to the antero-lateral margins of the body. These crabs, moreover, do not adopt burrowing habits. Their armature of spines, tubercles, and hairs is employed, as is well known, for protective purposes: in some cases possibly as an actual defence against attack, in others (i.e., Eurynome aspera) as a means of protective resemblance to their surroundings; but in the great majority as mere pegs and hooks for the fixation of foreign bodies, such as algae, hydroids, polyzoa, and ascidians, for purposes of concealment and disguise.

In the Catometopa (Land-crabs, etc.) the carapace is usually smooth over its whole surface. These animals often burrow in sand, but for the most part their burrows are permanent subterranean tunnels and chambers.

In the Cyclometopa, however—the group which includes most of our commoner British crabs—the back of the carapace is generally smooth, while the antero-lateral margins are in most forms conspicuously serrated. Most of these animals inhabit sandy or gravelly areas, and show a marked propensity towards burrowing habits. Their burrows are never permanent channels or tunnels in the sand, but are mere temporary excavations, the sand, mud, or gravel being in actual contact with their bodies when imbedded.

Sabellidae is the second most diverse polychaete family in the Adriatic Sea, after Syllidae. Herein we report the updated list of the Sabellidae and Fabriciidae families in the Adriatic Sea deriving both from literature data and presently conducted researches in the northern Adriatic. During these researches polychaetes were sampled from three offshore soft-bottom and three coastal rocky shore stations. Among the analysed material three Sabellidae species are new records for the Adriatic fauna, while four Sabellidae and one Fabriciidae species were recorded for the first time in the northern part. Two new species were found and described: Amphicorina rovignensis spec. nov. and Megalomma pseudogesae spec. nov. These findings increase the number of Sabellidae taxa recorded in the northern Adriatic from 29 to 38. Our results point out the lack of the recent taxonomic studies in the area, but might also indicate the widening of the species areal. Taking into consideration that studies on only six stations raised the number of known sabellid taxa from the area by 31%, our results support the need for the regular taxonomic updating of the polychaete fauna in the northern Adriatic.

In conjunction with a tagging experiment on Callista chione (L.) in 1976, a small number of the large bivalve Arctica islandica (L.) (Family Arcticidae) were also tagged in a similar manner with plastic discs cemented on to the shell with fast-setting cyanoacrylate adhesive. Arctica is less common in Whitsand Bay than Callista but extends into deeper water, 50–60m. Holme (1953) suggested that the species is long-lived and produced spat infrequently. A few young Arctica have been taken in Whitsand Bay (length 29–37 mm) and also, more commonly, specimens of 80–100 mm. In 1976 five Arctica were tagged and relaid, three of these were recovered in 1977 and one in 1978. Three more were tagged in 1978 and searched for without success in 1979. The recovered specimens did not appear to have moved at all. The results of shell length measurements, though meagre, indicated that growth was very slow. For a shell of 82 mm length the increase was 1–5 mm in a year. For a shell of 101 mm there was no increment after two years. For a shell of 102 mm the annual increment was probably 0-1 mm. In this instance it seems likely that the original length should have been 102–3 mm instead of 103–2 which was recorded. For a shell of 108 mm an increment of 0–3 mm was found after 12 months. From these results the average increment of shells over 100 mm length is likely to be of the order of 0-1 mm per year.

Harmeria scutulata, a cheilostome bryozoan with a circum-Arctic distribution, is an important component of intertidal and shallow subtidal rock communities. In terms of numerical abundance, H. scutulata can reach over 50% of total individuals within Arctic bryozoan assemblages. It is an annual, fast-growing species that loses over 70% of interactions for space with other organisms. Uniquely for a bryozoan, the subcircular colonies have large zooids at the centre ringed by a marginal zone of up to six generations of small zooids. This pattern is shown here to be due to polymorphism, reflecting a functional differentiation between large, feeding zooids (autozooids) and small, non-feeding zooids that brood embryos (gonozooids). The switch from the budding of autozooids to gonozooids occurs more or less simultaneously around the circumferential growing edge of the colony and is irreversible. Colonies apparently produce embryos only near the end of the growing season. Strong wave action and/or ice scour during the winter months destroys most of the colony but it is inferred that some of the gonozooids, which are more thickly calcified than the autozooids, overwinter, surviving into the spring and releasing their larvae to found a new generation of colonies. A formal systematic redescription of H. scutulata is given.

A karyometric analysis of the diploid complement of Procerodes dohrni (Turbellaria: Tricladida) was carried out on mitoses from regenerative blastema. P. dohrni has seven pairs of homologous chromosomes. Chromosome lengths decrease gradually and homologous pairs cannot be grouped. With reference to centromere position, chromosomes 1, 2, 3, 4 and 6 are metacentric, their centrometric indices vary from 46·74 to 39·82, while chromosomes 5 and 7 are submetacentric, their centromeric index being 34·63 and 29·86 respectively.

A method was developed to attach underwater acoustic transmitters on the knobby sea star Protoreaster nodosus. Cylindrical transmitters, each measuring 36 mm length × 13 mm diameter in size and 11 g in weight, were used in this study. Each transmitter was placed in a neoprene holder that was attached externally to the middle of one arm of P. nodosus with a nylon monofilament fishing line. Attachment was achieved by threading the monofilament line through two small perforations aborally along its mid-ridge and adorally through the ambulacral groove. Some 36 individuals were successfully tagged over a three-year period between 2007 and 2010 on an intertidal reef in Singapore using this technique. Tagging did not appear to affect survival, feeding or movement of sea stars during the period of attachment, which averaged 60 days. This method may work equally well with other types of tags, such as depth recorders and accelerometers.

The corallivorous gastropod Coralliophila meyendorffi (family Coralliophilidae) is a well-known predator of the coral Cladocora caespitosa, particularly in the eastern Adriatic Sea, where population outbreaks can drastically reduce coral cover. Coralliophila meyendorffi ranges in size from 5 to 40 mm in shell total length, and smaller specimens are often found living with the coral C. caespitosa. Specimens of C. meyendorffi feed exclusively on live coral tissue, stripping it from the calcium carbonate skeleton. Recent outbreaks of the gastropod C. meyendorffi have caused considerable damage on a C. caespitosa bank in Veliko Jezero (the Mljet National Park, eastern Adriatic Sea). The bank occurs at depths between 6 and 18 m, covering a 65  m2 area. During summer of 2010, a substantial outbreak affected about 5%t of the coral colonies. The gastropods were highly aggregated in sheltered areas of the coral bank (up to 41 specimens/dm2) with smaller clusters (from 8 to 12 specimens/dm2) on coral colonies that were influenced by strong bottom currents (up to 1.23 ms−1).

Two new species of ciliates parasitizing marine molluscs in the Yellow Sea were described using live observation, protargol and wet silver impregnation: Sphenophrya solinis sp. nov. from the gills of Solen grandis and Planeticovorticella paradoxa sp. nov. from the gills as well as the mantle cavity of Meretrix meretrix. Sphenophrya solinis is elongate boat-shaped, and characterized by having the right system of 5–6 kineties more or less distinctly longer than the left system of 3–5 kineties and the bud formed on the dorsal left of body during budding. Planeticovorticella paradoxa is a second member of the genus Planeticovorticella, and characterized by the free-swimming, cylindroidal trophonts usually with no stalk or with a very short and non-contractile stalk, the C-shaped macronucleus longitudinally oriented in mid-body, and the apically located contractile vacuole. The morphology, infraciliature and morphometry of the two new species were studied in detail and compared with those of their most similar congeners.

The model diatom Thalassiosira pseudonana is believed to be a single species with a global distribution, but it has not been confirmed previously whether isolates from different environmental and geographic origins are genotypically and phenotypically identical. In the present study, a polyphasic approach was employed to characterize nine clonal isolates, plus an additional replicate of one of the isolates, of the diatom T. pseudonana from culture collections to investigate whether there was any cryptic speciation in the publicly available strains of this species. Morphological analysis using scanning electron microscopy concluded that the strains were indistinguishable. Furthermore, conventional DNA barcoding genes (SSU rDNA, ITS1 and ITS2 rDNA and rbcL), revealed no nucleotide variation among the strains tested. On employing a whole genome fingerprinting technique, Amplified Fragment Length Polymorphism (AFLP), three clusters were revealed, although the level of variation between the clusters was surprisingly low. These findings indicate a low level of diversity among these cultured T. pseudonana strains, despite their wide spatial and temporal distribution and the salinity range of their original habitats. Based on the limited number of available strains, this suggests that T. pseudonana is a highly conserved diatom that nevertheless has an ability to tolerate wide ranges of salinity and populate varied geographic locations.

A cytological study was carried out on the main cells of the optic gland of male and female Sepia officinalis L. during sexual maturation (animals collected in the field). The results were correlated with experimental data on the mitogenic action of optic gland extracts collected during a period of secretory activity.

The main cells of the optic gland show some of the features of protein-secreting cells, although they are not very pronounced. The secretory activity of the cell was found to be correlated with a peak of mitogenic activity occurring in September/October in the case of the males and in November in that of the females. The secretion of gonadotropic mitogenic factor varies throughout the sexual cycle of Sepia officinalis. This activity is correlated with a rapid multiplication of spermatocytes and spermatogonia in the males, whereas in the females it corresponds to previtellogenesis.

The prosobranch snail, Hydrobia ulvae, lays eggs on the shells of neighbouring individuals where they are held together and protected by a covering of sand grains. The eggs develop within this egg mass, hatching as veliger larvae for which there are several descriptions (Henking, 1894; Thorson, 1946; Pilkington, 1971; Fish & Fish, 1974). It is clear that there is considerable variation in the size, pigmentation and swimming behaviour of veligers from different localities. The material used in the present study was from a population of snails in the Dovey estuary, Wales, which have free-swimming veliger larvae similar to those described by Thorson (1946). These have a single whorl to the shell; a shell length at hatching of 140–170 µm; a semi-lunate band of purplish black pigment on each velar lobe; a narrow band of pigment between the eyes and black pigment associated with the hindermost part of the intestine. In contrast, those from Ply-mouth hatch with one and a half shell whorls and a colourless velum (Lebour, 1937; Pilkington, 1971); a shell length of 340–390 µm and show complete suppression of the pelagic phase, the velar cilia being short and incapable of lifting the larva off the bottom (Pilkington, 1971). It has been suggested by Pilkington (1971) that the differences in size and swimming behaviour might be the result of the Plymouth larvae hatching at a later stage. The present account is the result of investigations into the effects of temperature and salinity on the survival of embryos to hatching and the duration of embryonic development.

During a period of five years in the mid-1970s, fish were collected at weekly intervals from the Severn Estuary and Bristol Channel. The resultant data on the abundance and lengths of these fish have provided valuable information on the times when the juveniles of several marine species are recruited into the estuary and on their pattern of growth during the first years of life (Claridge & Gardner, 1977; Titmus, Claridge & Potter, 1978; Claridge & Potter, 1983, 1984, 1985; Potter & Claridge, 1985). One of the marine species found in the Severn Estuary for which no seasonal data on density or body size have been presented is the sole, Solea solea (L.), whose relative abundance ranked it amongst the top ten species in two of the five years of our study (Claridge, Potter & Hardisty, 1986).

The Strait of Sicily in the middle of the Mediterranean Sea is considered a crossroads between the western and the eastern basins for species immigrating from the Atlantic Ocean and Lessepsian species. Among the latter, the African sailfin flyingfish Parexocoetus mento was recently collected from Lampedusa Island in November 2017, and represents the first documented record in Italian waters. In this paper, the morphological and meristic characteristics of this specimen are reported and discussed, compared with the other species of the genus Parexocoetus. Furthermore, as mapping and monitoring the distribution of invasive species is crucial to understanding their establishment and spread and then to manage the invasion process, the occurrences distribution of P. mento in the Mediterranean Sea was studied. The application of GIS-based spatial statistics allowed to identify significant clustering areas and dispersion areas of the species, summarizing the key characteristics, and underlining directional trends of distribution. GIS analysis identified two similar groups of records (1935/1966 and 1986/2017 time period), showing a change of distribution spatial pattern over time. An earlier spread direction in the Mediterranean east coast and a settled area of P. mento were found. The analysis also includes the specimen caught in Italian waters.

In July, 1924, 250 floating, and an equal number of bottom-trailing, bottles were put out at selected places in the western English Channel. Fifty of each type were put out at each of the two routine Stations E2 and E3, and the same number was “liberated” at each of three selected stretches along the steamship route from Southampton to St. Malo. Those surface bottles, which did not strand locally, travelled rapidly up Channel towards the North Sea and across it. Many bottles arrived in the Skager-Rack after performing their journey of some 700 miles at the rate of 6 miles a day and more. An adequate study of wind conditions, as recorded at several stations along the length of the Channel and at one station in the southern North Sea, revealed the fact that there was, for some 5½ months (counting from the time of liberation of the bottles), an almost uninterrupted predominance of south-westerly winds—as recorded at all stations considered. The whole area of the Channel was swept by south-westerly winds of average speed of some 9 miles a day for at least 5½ months subsequent to the time of putting out of the bottles. July, 1924, had (according to the Falmouth Observatory records) the largest proportion of westerly winds experienced for 54 years; 20 days of this month had winds with westerly components. The association of the unusually persistent westerly winds with the rapid travel of surface bottles towards and across the North Sea is interesting.

The nauplii of Balanus amphitrite (Cirripedia: Thoracica) were cultured on a daily diet of Chaetoceros gracilis at different concentrations. Both young (zero-day old) and aged (six-day old) cyprids were subject to attachment assays, followed by studies of juvenile growth and survival for two weeks under laboratory conditions. The TAG/DNA ratio of cyprid increased in the following order of food concentrations: 106>105>104 cells ml−1. More than 70% of cyprids metamorphosed in the presence of conspecific settlement factor, irrespective of their TAG/DNA ratio. The juvenile growth and survival in young cyprids surpassed that of the aged cyprids. The TAG/DNA ratio had no significant effect on juvenile growth and survival in both young and aged cyprids. The negative effect of delayed metamorphosis on juvenile growth and survival appeared to be independent of the TAG/DNA ratio.