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.

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.

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.

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.

In this research, we compared the anatomy and biomechanics of two species of mudskipper vs an aquatic sandgoby in view of terrestrial locomotion. Of particular interest was the relationship (if any) of pectoral fin movement with pelvic fin movement. We show that the pelvic fins of the terrestrial mudskippers studied herein, are retractable and move antagonistically with the pectoral fins. The pelvic fin of the sandgoby studied here is contrarily non-retractable and drags on any underlying substrate that the sandgoby tries to crawl across. We find that the pelvic and pectoral fin muscles of all fish are separated, but that the pectoral fins of the mudskipper species have bulkier radial muscles than the sandgoby. By coupling a detailed morphological investigation of pectoral-pelvic fins musculature with finite element simulations, we find that unlike sandgobies, the mudskipper species are able to mechanically push the pelvic fins downward as pectoral fins retract. This allows for an instant movement of pelvic fins during the pectoral fin backward stroke and as such the pelvic fins stabilize mudskippers through Stefan attachment of their pelvic fins. This mechanism seems to be efficient and energy saving and we hypothesize that the piston-like action might benefit pelvic–pectoral fin antagonism by facilitating a mechanical down-thrust. Our research on the biomechanics of tree-climbing fish provides ideas and greater potential for the development of energetically more efficient systems of ambulation in biomimetic robots.

In a communication to the Royal Society (Phil. Trans. vol. clxxxiv. 1894, and in this Journal, vol. ii. no. 1), I described a series of experiments in which light was directed upon the lower sides of flat fishes, by means of a tank with a glass bottom, and a mirror placed beneath it. I have now to record an observation which confirms my previous results in a most striking manner. Curiously enough, the effect I am about to describe, in some respects even more important as evidence than those obtained in my experiments, was observed accidentally, or at least incidentally, and was due to conditions which had been quite unintentionally produced.

INTRODUCTION

In 1976 the Fisheries Laboratory, Lowestoft, carried out 13 plankton sampling cruises off the north-east coast of England. They spanned the months February-November. From these cruises Harding et al. (1978) described the distributions of surface chlorophyll and nutrients and the production offish eggs and larvae. Reynolds (1978) described in more detail the distributions of chlorophyll and phaeopigments throughout the year, and Horwood (1982) detailed the distribution of zooplankton biomass. This study presents the species composition of the algae from a small region of the survey area illustrated in Fig. 1.

0-group bass were sampled from the shallow creeks of the Tamar and Camel estuaries at regular intervals from May to September in 1981 to 2000 to measure relative year-class abundance. From 1989 onwards classes were generally strong, especially those of 1989, 1992 (Tamar only), 1995 and 1998. Sampling at age-4, before departure from the nursery at the onset of adolescent movements, gave broadly similar relativities. Numbers were greater, and growth faster, in the Tamar than in the smaller and cooler Camel. Temperature was an important factor in both abundance and growth. Occasional major differences in abundance between the two estuaries were reported. Factors which might bias the age-4 result are considered. Other estuaries on the south side of the south-west peninsula, sampled less frequently, reflected Tamar abundances; others on the north side reflected Camel abundances. Limited analysis of stomach contents of older juvenile bass often present in the same habitats revealed no evidence of cannibalism on 0-groups. The shallow creeks of the Tamar and Camel were deserted in winter but a deeper creek on the Taw, frequented throughout winter, was sampled monthly in the 1982–1996 winters to measure losses, if any, in cold periods. In the mainly mild winters, losses were infrequent and small except in the five-week cold spell of early 1986, when the 1985 class suffered an estimated 58% loss in the Taw and possible total loss in the Camel and the Tamar. Sudden heavy flooding of the estuaries caused no apparent losses when they occurred in late summer and autumn but might be damaging if they occur soon after post-larvae arrive.

The prey size of young cuttlefish was investigated by measuring the size of entire animals, carapace, periopods, and otoliths in the stomach contents of specimens from Morbihan Bay in 1994–1996. The young of the Sepia species consumed a wide range of prey sizes. The size of all isopods and amphipods was less than the 50% of those of the Sepia. The size ratio of brachyurans varied between 14 and 37% of the dorsal mantle length of the cuttlefish. The young could catch fish species which were three times larger than itself.

The vertical distribution, morphology and diet of Proboscidactyla stellata (Cnidaria: Limnomedusae) were studied in Lough Hyne over a two year period. Vertical hauls of four depth strata, 40–30 m, 30–20 m, 20–10 m and 10–0 m, were taken monthly and at 4 h intervals for a period of 48 h in July and 24 h in September 1994. Proboscidactyla stellata was largely concentrated in the lower 20 m of the water column reaching a maximum of 21 m−3 at 30–20 m depth in June 1993. An oxythermocline occurred at 25–30 m depth in the summer and autumn months of 1993 and affected the vertical distribution of the medusae. Six morphs of the species, varying in the number of gonads, were found in the lough. Bivalve veligers, which P. stellata actively selected, formed 83% of the diet.

Recent observations of unusual mass stranding and mortality of two Indian Ocean crustacean species, the swimming crab Charybdis smithii and the mantis shrimp Natosquilla investigatoris, are documented and analysed. Strandings of C. smithii were observed for the first time in the equatorial Indian Ocean, the main area of its pelagic distribution. Strandings of mantis shrimps are reported from throughout the western Indian Ocean; occurrences of mass stranding in the Maldives Archipelago mark an extension of the known range of N. investigatoris into the central Indian Ocean. Mortality of crabs probably represents a ‘catastrophic event’. In contrast, mantis shrimp strandings, which were always associated with a sudden increase of its biomass (‘blooms’), are apparently post-reproduction mortalities indicating potential semelparity for this species.

Skulls of 153 porpoises from the Sea of Azov and the Black Sea were studied. Thirty-seven skull measurements were examined. Skull growth in porpoises can be divided into five periods. The greatest changes in growth patterns occur after the first weeks of life. A ‘relay effect’ in growth of some structures (e.g. rostrum) was observed. Individual variation usually increases when a given structure grows intensively; however, some structures are highly variable over the entire lifespan. Sexual dimorphism is demonstrated in most of the measurements in adult animals. Temporal variation is minor. Skull structures are characterized by six types of allometry; three of them demonstrate drastic changes of allometry during lifespan, thus requiring two allometric equations to describe them. Skull proportions change critically during the first weeks of life. Six groups of correlated measurements differing in the pattern of correlation links during ontogeny were identified. Three factors play the most important roles in forming the definitive skull proportions: correlation between adjacent structures, impact of total skull size and inclusion in a certain functional complex.

Amiantis purpurata shells from the San Matías Gulf (SMG) were analysed in order to compare both morphology and size throughout the late Quaternary in relation to environmental changes. Shells from modern beaches, Holocene marine assemblages (late Holocene, 3630 ± 100 years bp) and interglacial Pleistocene marine assemblages (MIS 5, 100 ka years bp) were studied by measuring the height and length, and using the elliptic Fourier analysis (EFA) to take an outline contour. The Pleistocene shells were smaller, more elliptical and with a deeper lunule than the Holocene and modern ones. No significant differences were recorded in the allometry index throughout the late Quaternary. The variation in size and shape of the A. purpurata shells could be related to the phenotypic plasticity of this species as a response to the environmental changes registered in the SMG during the Quaternary. These changes include variations in sea surface temperatures, salinities and substrates, and also water circulation changes, which would have modified nutrient availability. Morphological changes imply burrowing activity, mechanical stability, nutrient uptake and defence response to predation.

Pacifigorgia marviva, a new shallow-water species of the family Gorgoniidae, was found in Coiba National Park, Pacific Panama at 35–40 m depth. It is characterized by having white to cream, small, erect colonies composed of 1–4 fronds, stems short or absent network irregular and open without fan midribs, and polyp mounds slightly raised and sparsely distributed. All sclerites are colourless. Coenenchymal sclerites mostly composed of long spindles reaching up to 0.25 mm in length, and long and thin anthocodial rods, up to 0.16 mm in length. Morphological characters are analysed and illustrated. Scanning electron microscopy was used for sclerite study. The new species is herein described and compared with other similar species reported from the eastern Pacific. Pacifigoria marviva increases the number of Pacifigorgia species to 35; 20 in Panama representing 57% of the genus in the eastern Pacific, followed by Costa Rica and Ecuador with 14 and 10 species, respectively.

A potential new species of Barracuda Sphyraena intermedia sp. nov. (Perciformes: Actinopterygii) is reported from the Gulf of Taranto in the central Mediterranean Sea. This classification was based upon a thorough anatomical comparison with well documented species from the region (Sphyraena sphyraena and Sphyraena viridensis). Principally, Sphyraena intermedia sp. nov. differed from the other species within the genus in terms of body shape, otoliths, dentition and pyloric caeca.

In the third paper about Ampharetidae from Japan, we describe six species that belong to the ‘Amphicteis genus complex’. We divide this complex into the genera Amphicteis Grube, 1850, Paramphicteis Caullery, 1944, Phyllamphicteis Augener, 1918 and Watatsumi gen. nov. Paramphicteis is considered senior synonym of Pseudoamphicteis Hutchings, 1977 and is characterized by pinnate buccal tentacles. Watatsumi gen. nov. with its type species Watatsumi grubei sp. nov. is characterized by the lack of prostomial glandular ridges, the presence of pinnate buccal tentacles, and inconspicuous nuchal ridges. Two of the Amphicteis species are new to science, including A. spinosa sp. nov. and A. taurus sp. nov. Paramphicteis weberi (Caullery, 1944) comb. nov. was transferred from Amphicteis because we found pinnate buccal tentacles in addition to four pairs of foliose branchiae. Paramphicteis foliata (Haswell, 1883) comb. nov. was transferred from Phyllamphicteis because it has pinnate buccal tentacles. Amphicteis uncopalea Chamberlin, 1919 and Paramphicteis angustifolia (Grube, 1878) are newly recorded from Japanese waters. Amphicteis orphnius Chamberlin, 1919 is considered senior synonym of A. obscurior Chamberlin, 1919. A comprehensive table with diagnostic characters of all species of the Amphicteis complex with pinnate buccal tentacles is provided.

Harpacticoid copepods (Crustacea) comprise an important taxon of the sedimentdwelling meiofauna, generally being numerically inferior to only the Nematoda (Hulings & Gray, 1971). This paper reports those species comprising the fauna of the sediments of the River Ythan estuary, particularly the intertidal sediments, and describes some of the properties of the meiobenthic copepod community structure.

A small collection of horny sponges from the north-eastern coast of Papua New Guinea is recorded. It consists of 19 specimens belonging to ten species, of which three are new: Thorectaxia papuensis, Chelonaplysilla delicata, Anomoianthella lamella. Thorectaxia is proposed as a new genus in the family Thorectidae.

Several colonies of the phlebobranch ascidian Perophora japonica were found during 1999 at a marina in Plymouth Sound, Devon, UK. The species was still present in the spring of 2000. This appears to be the first record from British coasts of the species, which is native to Japan and Korea but is previously known from northern France. The stolons of P. japonica bear distinctive, star-shaped terminal buds, which are bright yellow in the Plymouth population. Comparison is made with Atlantic representatives of the genus, particularly the native British species P. listeri.