The distribution, reproductive biology and shell utilization pattern of two sympatric hermit crab species in Akkeshi, north-eastern Hokkaido, were examined. Although spatial distributions of Pagurus middendorffii and P. brachiomastus highly overlapped and their body sizes were similar, their shell utilization and breeding season markedly differed. Since interspecific differences in the shell utilization pattern agreed with the experimentally determined shell preference difference, we conclude that the interspecific difference in shell preference results in the shell utilization patterns observed in the field. The interspecific difference in the reproductive period, shell utilization pattern and shell preference are concluded to be factors that allow the coexistence of the two Pagurus species in Akkeshi. This study is an example of resource partitioning by coexisting hermit crabs.

Dynamics of Synechococcus (Syn), Prochlorococcus (Pro) and picoeukaryotes (Euk) was studied at 92 stations in the Pearl River Estuary and adjacent shelf waters in the winter of 2006 using flow cytometry. The average cell abundance of photosynthetic picoplankon (Pico) was 104 cells/ml. Picoeukaryotes was the dominant group in the inner estuary where Pro was absent. Synechococcus was dominant in the coastal and open waters. The proportion of Pro was higher in the open than in the coastal waters. The change of Pico community structure from the inner estuary to the open waters is related to the changes in hydrochemical dynamics. The vertical variations in the abundance and community composition of Pico were not significant. The abundances of Pro and Syn were positively correlated with temperature, salinity and pH, whereas they were negatively correlated with dissolved oxygen (DO), suspended sediment concentrations (SSC) and nutrients (nitrogen, phosphorus and silicon) concentrations. But the correlations between %Euk (as of total pico) and these environmental factors were opposite to those between the abundance of prokaryotic cells (Pro and Syn) and the environmental factors. %Euk had significant negative correlations with temperature, salinity and pH, and positive correlations with DO, SSC and nutrients. There were differences in the niches between prokaryotic cells and picoeukaryotes. Prochlorococcus and Syn were dominant in the warm waters with high salinity, low SSC and low nutrient concentrations, while %Euk was higher in the cold waters with low salinity, high SSC and high nutrient concentrations. Results of principal component analysis and regression analysis indicated that the relationship between the abundances of Pico and the environmental factors was a compound function (y = b0(b1)x), and that between the abundances of Pro, Syn or %Euk and the environmental factors was a linear function.

The cirri of the digital tentacles of Nautilus pompilius are covered by annular ridges, more pronounced on the oral (adhesive) than the aboral side. On the oral side the epithelium is thicker on the proximal and outer surfaces of the ridges than on their distal surfaces. Prominent electron-dense granules occur in the cells of the thick epithelium, but are absent from the thin epithelium and the epithelium of the aboral surface. These granules contain mucopolysaccharide and may be responsible for adhesion.

The digital tentacles of Nautilus are used for attachment to, for example, prey, the substratum, or the partner's shell during mating. Their general structure and histology have been described by Owen (1832), Willey (1898), Barber & Wright (1969), Fukuda (1987) and Kier (1987). The mechanism of adhesion is still uncertain. Barber & Wright (1969) report epithelial cells of two types: pigmented cells containing pigment granules 0–5–1 µm in diameter, interspersed with a small number of mucus-producing cells which may help with the adhesive process.

A new species of the marine gastrotrich taxon Thaumastoderma is described. A single specimen of this species, Thaumastoderma antarctica sp. nov., was extracted from silty sediment sampled at one station of the Andeep-1 cruise, about 150 km to the north of the South Shetland Islands (Drake Passage, South Atlantic Ocean). This paper provides the first record of this genus from the deep sea and the second description of a macrodasyid gastrotrich living in an abyssal habitat. The new species is characterized by several apomorphic features, among them a caudal pair of strongly elongated dorsal cirrata tubes. A phylogenetic analysis of the genus Thaumastoderma reveals that Th. antarctica is closely related to Th. coronarium and Th. appendiculatum. Furthermore, the analysis offers an evolutionary scenario and a hypothesis for the internal phylogeny of this taxon while supporting its monophyly. It is the first time a cladistic analysis has been conducted for a delimited group of gastrotrichs, i.e. for all known members of a genus.

Reproductive properties of Eledone moschata from the north-eastern Aegean Sea are reported for the first time. A total of 471 specimens was collected during monthly samplings from December 2004 to November 2005. The mantle lengths of the species were between 4.5 and 15.0 cm with an average of 8.1 cm ±0.15 for 204 males, and between 2.7 and 14.0 cm with an average of 7.8 cm ±0.12 for 267 females. The annual sex ratio (males: females) of the sampled specimens was 1:1.31. Maturity stages were recorded on a monthly basis in both sexes. The highest monthly percentage of mature females (21%) and males (46%) was recorded in January 2005 and June 2005, respectively. The monthly and seasonal gonadosomatic index (GSI) results indicated that E. moschata shows two annual reproduction peaks for each sex. For males, the first spring peak occurs in March–June and the second, autumn peak is in November. For females, the first summer peak occurs in May–June and the second, winter peak is in January, respectively. On the other hand, the reproductive season extends from November to July with two peaks in the Aegean Sea. Total oocyte stock varied from 273 to 2896 with a mean of 836 ±193 oocytes. The mean size of the oocytes was 6.26 ±0.10 mm. The maximum oocyte size found was 10.7 mm. The mean length of spermatophores was of 13.66 ±0.08 mm (range: 7.3–18.3) and their average number was 52 ±6 (range: 6–172).

The small-sized copepod community structure (<1  mm) and its response to environmental variability was examined during an annual cycle in Kalloni Gulf, a semi-enclosed coastal system in the NE Aegean Sea. Α 90 µm net was used in order to adequately sample the smaller copepod fractions. In the copepod ecology the spatial patterns dominated over the seasonal. Total copepod abundance increased towards the inner gulf area while diversity indices followed the opposite trend. The inner gulf copepod assemblage area was affected by the increasing magnitude of eutrophication, characterized by high abundance values, low species richness and dominance of a single species (e.g. Oithona nana). A clear seasonal succession of species was observed, ordered by temperature, salinity, chlorophyll a, heterotrophic bacterial biomass, organic and inorganic nutrients. Freshwater inputs and the subsequent nutrient inflow was a dominant phenomenon enhancing copepod production and negatively affecting the biodiversity of the assemblage. The great contribution of copepod larval stages in the total community and their year-round presence indicate the continuous production of copepods during the annual cycle, highlight the importance of the smaller size fraction and encourage the use of finer mesh-size nets when assessing the structure and dynamics of copepod communities.

Perkinsus marinus, a protozoan parasite of oysters, is an important cause of oyster mortality in the Gulf of Mexico and along the south-eastern coast of the United States (Hofstetter, 1977; Quick & Mackin, 1971). Infections are patchily distributed on many reefs, often with uninfected oysters adjacent to infected oysters. The primary mechanism of transmission from one oyster to another is through the water (Ray, 1954; Mackin, 1962; Andrews, 1965). Because dilution rapidly reduces the number of infective elements below the dosage required to initiate new infections (Andrews, 1979), transmission is most efficient over very short distances and declines rapidly within a few metres of the source.

Since April, 1921, observations of temperature and salinity have been made at depths from top to bottom of the sea at Station El, 20 miles to the south-west of Plymouth, where the depth is 70 metres. These observations already throw some light on the causes of different sea temperatures during the same month in different years. As these temperature differences from year to year play an all-important part in the life of cold-blooded marine animals (1), it is of particular interest not only to follow their seasonal changes, but to arrive as far as possible at the causes which govern them.

Changes in salinity and the temperature conditions during 1921 showed a marked inflow of warm highly saline Atlantic water into the English Channel, and a very marked inflow into the El area during September, October and November of that year (2). From that time until the end of 1923 there has been an irregular fall in salinity of the water at El.

Young estuarine bass of the 1976 and 1977 year classes were examined for gill parasites between February 1978 and June 1979. 344 specimens of the copepod Lernanthropus kroyeri were recovered from 177 of 289 fish. The distribution of the copepods on the gills showed clear preferences for site of attachment. With 48 such sites delineated per fish, 143 of 183 female copepods favoured a single site – the internal face of the medial sector of the posterior hemibranch of the second gill arch. 57 of 161 male copepods chose attachment to the external face of the medial sector of the anterior hemibranch of the second gill arch. Only seven copepods in all were found attached at any of the twelve possible sites on the first gill arch, and none at all at the six possible sites on the posterior hemibranch of the fourth gill arch. Explanations for the observed distribution are discussed in terms of the strength of the branchial ventilation currents over the different gills coupled with observations on the special respiratory adaptations of these parasites.

The Phylum Chaetognatha consists of morphologically and biologically similar species and its relationship with other invertebrate groups is obscure (Hyman, 1959; Ghirardelli, 1968). The possibility of regenerative power has been investigated as one of the clues to the affinity of the phylum. Kulmatycki (1918) made cross-sectional and diagonal cuts through the body and tail fin of Spadella cephaloptera Busch and reported that this species could regenerate the whole caudal section including the body proper. Further support for regenerative ability came from Pierce (1951) who caught 26 specimens of Sagitta enflata Grassi and Sagitta helenae Ritter Zahony which appeared to be in the process of regenerating their heads (presumably lost to a large predator). He noted that the loss of this section of the body did not kill the animal. Both Kulmatycki and Pierce are cited in Hyman's (1959) important review of the phylum and headless chaetognaths have been referred to as animals with regenerating heads (e.g. Almeida Prado, 1968).

In the year 1890 I tried an experiment upon young flounders, with the object of discovering what would be the effect upon the lower sides of the fish if these sides were continually exposed to daylight. Under ordinary conditions the upper side of the fish is dark-coloured, the lower side white; and the upper side is exposed to light, while the lower side being usually in contact with the ground, and always turned away from the sky, is protected from the light. A connection between the difference of the two sides in relation to light and in coloration naturally suggests itself. If the difference in coloration is due to the difference in the exposure of the sides to light, when the lower side of the fish is kept exposed to the light it ought to become coloured.

Mysids are common and abundant organisms in estuaries and coastal waters, where they have a central role in the functioning of food webs. The Río de la Plata (RdlP) is a major estuary that affects biogeographic patterns of marine coastal organisms in the south-west Atlantic, but studies of the plankton in the RdlP are scarce. Knowledge of the mysid fauna in particular is very limited with a single species (likely alien, Neomysis americana), traditionally known to inhabit this 38,000 km2 estuary, and a second one, Mysidopsis tortonesei, only recently reported. The purpose of this paper is to contribute with the knowledge of the mysid fauna of this ecosystem by exploring the spatial distribution and in situ salinity preferences of N. americana and M. tortonesei in the mixohaline region of the RdlP during austral autumn, 2001. Both species showed clear and contrasting haline affinities that resulted in an almost perfect spatial segregation within the study area. Neomysis americana occurred preferentially in oligo- and meso-haline conditions (range <1 to 33.37, but most abundant at salinities <28), while M. tortonesei occurred at salinities >28. Temperature range was quite narrow and it was unlikely that it affected mysid distribution in the estuary. Temporal variability in observed patterns, as well as the role of biological interactions in shaping spatial distribution of N. americana and M. tortonesei within the estuary are subjects that deserve further attention in future studies.

Whilt working at the life histories of the euphausiids occurring in the English Channel, and also having had opportunities of examining the larvae of several other species belonging to different genera from various localities, the writer noted certain features in the larvae which usually enabled the genus to be distinguished easily. The chief specimens were obtained from plankton collected by Mr. F. S. Russell within a radius of twelve miles from Alexandria, Egypt, whilst working for the Egyptian Fisheries Department. The larval euphausiid material from this collection is rich, and an account of it will soon be published. In the meantime the following general notes are offered, as at present little is known of the systematics of euphausiid larvæ. As several workers are occupied with this group, so important from the point of view of the Fisheries, it seemed advisable to bring all that is known together. In so doing it has been found possible to form a working scheme, from which, being given a series of larvæ of any species, one is enabled to determine the genus. For this scheme the order of development of the pleopods has been taken as the main factor, as it is found that the pleopods develop differently in several of the most important genera.

Measurements of current at the Seven Stones Light Vessel, 50° 03·5' N. lat., 6° 05·1' W. long. (for position, see Cooper, 1960b, fig. 1) were first made with the Carruthers Drift Indicator between 17 August and 15 September 1933 (Carruthers, 1934). The much longer series with the Vertical Log between July 1939 and April 1941 showed average travel of the residual cur-rent at a rate of 2·5 miles per day towards east-south-east (110° true) (Carruthers, Lawford & Veley, 1951). It was shown clearly that there was a strong causal connexion between the direction and strength of the wind and direction and strength of current, but that there were evidently other factors concerned as well. These current measurements were not easy to reconcile with deductions from the observed distributions of temperature and salinity in the area (Matthews, 1914; Harvey, 1925, 1929; Cooper, 19606). A rational explanation could be achieved if it is assumed that the passage of water from the English Channel to the Bristol Channel occurs intermittently and is confined to a narrow current close into Lands End. This ‘corner current’ rarely extends as far west as the Seven Stones Light Vessel.

A spectral emission curve for the light of Pholas dactylus has been determined by means of spectral niters and photomultiplier cell. Emission extends from about 440 to 670 mμ, with a maximum at about 490 mμ. The emission curve is compared with the action spectrum determined by Hecht.

The consumption or scavenging of fish in the water column at depths from 75 to 275 m in Algarve (southern Portugal) trawl fishing grounds was evaluated. Longlines were used to suspend baits throughout the water column while electric fishing reels were used to simulate sinking discards. Eighteen species were caught, with higher catch rates near the surface than near the bottom. However, scavenging rates were generally highest near the bottom and lowest in the middle of the water column. At depths less than 100 m the majority or all the fish were scavenged throughout the water column, while at depths greater than 200 m most of the fish were untouched after periods of time greater than would be required for them to sink to the bottom. Since other studies have shown that most small fish discards are scavenged at the surface by sea birds and most of the discarded species that sink are either too large or not attractive to pelagic predators, these results suggest that mid-water scavenging of trawl discards in deep water is relatively unimportant.

A description has been given of a mating which produced a great range of eye-irregularity in the offspring. Not only were the size, shape, and pigmentation affected, but the eye-structure itself, many cases occurring in which one eye or even both eyes were missing at birth.

This experiment adds another proof to the statement that the farther removed from the normal an animal is, the lower its viability. The mortality was much higher amongst the abnormals, and breeding experiments with the survivors were exceedingly difficult on account of the trouble experienced not only in rearing them to maturity, but in finding suitable mates. The cannibalism of the males of this stock made it almost impossible to use them, and small, not too vigorous, males had to be sought in the Albino No-white strain.

In three of the One-eyes, i.e. those in which one eye was present at birth, and no trace of a second could be seen (even with a high power), a very imperfect second eye developed later, after several moults had taken place. An example, CN.220c, is illustrated in Text-fig. 5 (List, p. 384).

The first zoeal stages of the snapping shrimps Alpheus carlae and A. intrinsecus from Brazil were obtained from laboratory-hatched specimens and a detailed morphological description is provided. The morphological characteristics of both species are compared with available descriptions of other Alpheus species with a known first zoeal stage. Remarks from a semi-quantitative comparison of species belonging to A. armillatus species complex (A. carlae and A. brasileiro) and a comparison between larvae of A. intrinsecus from two localities in Brazil are presented. It was possible to distinguish first zoea of both species from the other congeners based on morphology. No intraspecific variability was detected between A. intrinsecus larvae obtained from two locations. Some structures showed differences between species of the A. armillatus complex. However, generalizations and conclusions based on larval morphology for taxonomic rearrangements at this point need to be made with caution and accuracy, since data of a sufficient number of species are not yet available for comparison.

To demonstrate the effectiveness of microarrays for the detection of jellyfish, we developed a low density DNA chip based on the mitochondrial COI gene sequences of scyphozoans (jellyfish). We designed species-specific oligonucleotide probes by sequence comparisons between scyphozoans and other cnidarians such as hydrozoans and anthozoans. Each amine-labelled capture probe was arrayed onto a silylated slide. PCR products of the COI gene were hybridized to the DNA microarray that contained COI consensus sequences. We tested the ability of the DNA chip to discriminate between species from the genera Aurelia and Chrysaora based on samples of both species from the polyp and ephyra stages. The array produced unique hybridization patterns for each of the two tested jellyfish species. Furthermore, we were able to simultaneously detect individual jellyfish species from mixtures of these two different species in the laboratory and from environmental samples. These results show that the low density DNA chip that we designed can be used as a technical platform for parallel molecular detection of various jellyfish species.