Thermal perception is crucial for the fitness of marine invertebrates in intertidal and shallow waters. TRPA1 is a non-selective cation channel that belongs to the TRP family with pivotal roles in initiating signal transduction of thermal perception. We investigated expression patterns of SiTRPA1 in different tissues (tube feet, coelomocytes, gonads and gut) of the sea urchin Strongylocentrotus intermedius. SiTRPA1 expression patterns under acute and long-term temperature stimuli were investigated in tube feet of sea urchins. In the present study, the highest expression of SiTRPA1 was detected in tube feet of S. intermedius. The SiTRPA1 expression level in tube feet were significantly 235.7-fold, 450.0-fold and 3299.7-fold higher than those in the coelomocytes, gonads and gut (df = 3, F = 47.382, P < 0.001). Expression levels of SiTRPA1 in the other tissues (coelomocytes, gonads and gut) were not significantly different (df = 3, F = 47.382, P = 0.972). There was no significant difference of SiTRPA1 expression among all groups in the acute temperature increase experiment (df = 4, F = 0.25, P = 0.902). In the acute temperature decrease experiment, the expression of SiTRPA1 showed no significant difference among all groups (df = 4, F = 1.802, P = 0.205). With long-term exposure (6 weeks) to different temperatures, SiTRPA1 expression in the low temperature group (10°C) was significantly higher than those in the high temperature (20°C) and the control groups (15°C) (df = 2, F = 9.57, P = 0.014). There was no significant difference of SiTRPA1 expression between the high temperature (20°C) and the control temperature (15°C) groups (df = 2, F = 9.57, P = 0.808). These results indicate that SiTRPA1 expression significantly responds to long-term low temperature but not to acute temperature decrease. The present study provides new insights on the distribution and temporal expression of TRPA1 in marine invertebrates after acute and long-term temperature stimuli.

There have been recent attempts to improve our knowledge about dinoflagellates of the order Dinophysales either in Mexican marine waters or worldwide, and although new records and even new species have reliable illustrations and descriptions, this group is so diverse that it needs to be studied in more detail. This paper is the product of the analysis of net phytoplankton material collected from coasts of the tropical Mexican Pacific (Gulf of California, Central Mexican Pacific and Gulf of Tehuantepec), and the southern Gulf of Mexico. Material was studied using light microscopy and scanning electron microscopy (SEM). Eleven taxa (10 species and one variety) of the section Hastata were fully identified, with nine species studied for the first time by electron microscopy (only Dinophysis hastata and D. schuettii had been previously studied by SEM), and including seven new records for the Mexican Pacific (Dinophysis monacantha, D. nias, D. phalacromoides, D. pusilla, D. swezyae, D. uracantha var. mediterranea, and D. uracanthoides), and one new record for the Gulf of Mexico (Dinophysis uracanthoides). Two species remain as unidentified, as only one specimen of each was found. Additionally, we studied in detail the new species, Dinophysis conjuncta sp. nov., for which a full description is provided. Descriptions, measurements, illustrations and local distribution data are provided for each species.

This paper describes the responses of a squid (Alloteuthis subulata) and a fish (Trachurus trachurus) to changes in the angular distribution of light.  An apparatus was made that simulated the angular distribution of daylight in the sea. The apparatus enabled the direction of the brightest light to be changed and the positions of the animals in response to these changes were observed. Squid viewed head-on were observed to roll by a maximum of 20° when the incident light source was at angles between 20° and 90° (where 0° is vertically downwards). When viewed laterally, i.e. in the pitch plane, the squid were observed to position themselves more closely with respect to the angle of the light source, they swam in a near vertical plane when the incident light source was at an angle of 90°. Swimming movements in the roll and pitch plane became more horizontal with positions of the light source between 90 and 180°. Horse mackerel, in contrast, inclined their dorsal surfaces to almost perfectly match the angle of the incident light source, even swimming upside-down when light came from below. These experiments also revealed that squid display a counter-shading chromatophore pattern (‘Flexible Countershading’) in response to light coming from the sides, which involves darkening the side of the body facing the brightest light. The use of chromatophores in this way may explain why the dorsal light reflex in squid is so weak compared to that of fish.

The early life history traits of the labrisomid blenny Auchenionchus crinitus (Jenyns, 1842) from subtidal rocky reefs were studied, based on microstructure analysis of sagittae of their pelagic larvae (4.01 mm NL −12.50 mm SL). Ichthyoplankton was collected in shallow (<20 m) nearshore waters off Isla Santa María, Antofagasta, northern Chile every 15 days during austral autumn–winter 2014 (five sampling days). During late May and early June, larval abundance was low (median ± MAD, 39.06 ± 5.08 ind. 100 m−3), increasing significantly during mid-June to early August (110.98 ± 47.66 ind. 100 m−3). Using 354 sagittae, the back-calculated hatch dates indicated the occurrence of three hatching events, two in autumn and one in winter. Hatching occurred mainly during the illuminated phases of the lunar cycle. All three batches had similar estimated larval sizes at hatch (3.2–3.7 mm SL), as well as similar growth rates (0.19–0.22 mm day−1) during the first 30 days of life. During the study period, shallow waters were well mixed, with seawater temperature of 14.73 ± 0.58°C and salinity of 34.84 ± 0.04. This is the first estimation of early life history traits of this cryptobenthic species from rocky reefs of Chile.

The distribution, abundance and seasonal occurrence of larvae of mackerel (Scomber scombrus L.) are described from routine Continuous Plankton Recorder (CPR) sampling around the British Isles over the period 1948–78, and from more intensive CPR sampling in the Celtic Sea in 1977. There were two main areas of larval concentration: in the North Sea and over and adjacent to the Celtic Plateau; subsidiary aggregations were observed to the northwest of Ireland and to the west of Norway. There were some similarities between the distribution of larvae around the British Isles and that of adult Calanus spp. In the North Sea there was a southerly shift of larval distribution over the period 1948–77; over a similar period the abundance of larvae increased to reach high numbers by the late 1950s and subsequently declined after the mid-6os. To the south-west of the British Isles numbers of larvae showed a long-term decline. The long-term trends of distribution and abundance are discussed in relation to concurrent biological and environmental change. The clearest relationship was found between the numbers of mackerel larvae in the North Sea and sea-surface temperature in the North Atlantic, which suggests a common causative agent for both sets of observations; also, there was a weak relationship with both spawning stock biomass and sea-surface temperature at the spawning areas. In the North Sea the seasonal occurrence of larvae was from May to August, the majority being taken in June and July; over the period 1948–77 the seasonal time of occurrence of highest numbers of larvae has remained relatively constant. In the Celtic Sea the seasonal occurrence of larvae was spread over a longer period, from March to August, with relatively high numbers from March to June; over the period 1950–78 the time of occurrence has been variable, possibly with a tendency towards later timing in more recent years.

A biometric analysis was performed on crabs (Paguristes eremita) collected in the soft bottom of the Sicilian Channel (southern Mediterranean Sea), on associated suberitid sponges (Suberites domuncula), and on shells inside sponges. Populations of crabs living in sponges overgrown on shells were compared with populations of crabs living in shells associated with the sea anemone Calliactis sp. Results from multivariate ordinations (principal component analysis, non-metric multidimensional scaling) and univariate linear regression analysis were discussed considering two possible models: (1) sponges are preferred to clean shell because they are a growing home; and (2) sponges are not preferred: they are used as an ‘emergency’ refuge by crabs searching for shells suitable for carrying sea anemones. Differences in shell assemblages and in biometric variables between populations living in sponges and populations living in shells associated with anemones, suggest that crabs, especially small ones, may live briefly in sponges and that sponges may be inhabited by a series of crabs over a long period.

Sponges are a key component of the deep-sea benthos, where they form structurally complex habitats and provide numerous ecosystem goods and services. However, there is still an enormous knowledge gap regarding the diversity, distribution and systematics of this group. This special volume presents the results of the 1st International Workshop on Taxonomy of Atlanto-Mediterranean Deep-Sea Sponges, whereby world experts worked together to start filling in this gap. Herein, new species are described, new sponge-dominated communities are reported, and diversity and distribution patterns are enlightened for this area.

In Britain, the cushion star Asterina gibbosa Pennant 1897 (Echinodermata, Asteroidea) is confined to the west coast, where it occurs on rocky shores, often sympatrically with the closely related Asterina phylactica Emson & Crump 1979 (Crump & Emson, 1983; Emson & Crump, 1984). The vertical distribution of A. gibbosa extends from about 100 m depth, into the intertidal; however, littoral cushion stars occupy rock pools and relatively damp habitats such as gulley walls, crevices, overhangs and the underside of boulders, generally on the lower shore (Emson, 1979). On shores with rock pools, cushion stars may extend their upper limits of vertical distribution but not beyond the mean high-water neap-tide level (Crump & Emson, 1978). Absence of A. gibbosa from higher shore levels has been related to intolerance to desiccation and high temperature, inadequate food supply, and complex behavioural responses to gravity and light (Crozier, 1935; Emson, 1979; Crump & Emson, 1983). Prior to the present study, it has not been possible to discuss the influence of respiratory requirements on the vertical distribution of this species.

In the common sole Solea solea retinomotor changes take place. The retinal pigment usually expands in the light and cones shorten; reverse changes take place in darkness.

There are no species of salps (Order: Salpida) indigenous to British waters. Those species that can be found, the most abundant being Salpa fusiformis Cuvier (Fraser, 1981) are carried to British and Irish waters from the open ocean of the western Atlantic. Because of this salps can be good indicators of oceanic water movements near to Britain (Fraser, 1981). The largest species of the Salpidae is Thetys vagina (Tilesius, 1802) which generally reaches ≥230 mm in total length (TL) in the solitary asexual form and ~250 mm TL in the aggregate sexual form (Metcalf, 1918; Fraser, 1981). However, a solitary form measuring 333 mm TL was caught in a trawl from the Hawaiian islands (Nakamura & Yount, 1958). The distribution of T. vagina is usually limited to warm water throughout the Atlantic, including the Mediterranean, Indian and Pacific Oceans (Berrill, 1950). Up to 1981 there have been only two records of T. vagina in British waters (Fraser, 1981). This short paper describes, to the best of my knowledge a third recording of this salp from British waters.

In Pakistan, although the sea cucumber fishery has not yet been developed, Holothuria arenicola is abundant on its coast. Nineteen months of sampling was carried out to study the population structure, allometric relationships and reproductive status of H. arenicola stocks in Manora and Buleji rocky shores. All measured biometric characters showed significant temporal variations and width/length, weight/length, gutted weight/length and gutted weight/weight relationships followed negative allometry, indicating a change in body shape as the animal grows. Length-frequency distribution analysis was bimodal in both summer and autumn consisting of small-sized and medium-sized individuals while in winter and spring three modes were found at Manora. At Buleji, the population was unimodal in all seasons consisting of small-sized individuals. Sex in H. arenicola cannot be determined externally but can be identified on examination of gonad colour which is orange-like in females and creamy yellow in males. The sex was further confirmed on histological examination and maturation was divided into five stages, i.e. undetermined, early developing, late developing, mature and partially spawned. The sex ratio in H. arenicola was approximately 1:1 and increase in gonad index was observed during spring and early summer, followed by a decrease in GI in autumn and winter, which showed the spawning followed by resting phase. The GI showed a significant negative correlation with salinity and non-significant correlation with temperature. There is a need to undertake more biological/ecological studies on H. arenicola in order to take effective measures for its management.

Zidona dufresnei (Donovan, 1823) is a big-sized and long-lived snail endemic to the south-western Atlantic where it dwells in sandy bottoms between five and 115 m; females lay big egg capsules from which crawling juveniles emerge. An unusual population of Z. dufresnei inhabits the low intertidal and shallow subtidal zone of San Antonio Bay, the southernmost location of the species, where it faces many threats. The aim of this study is to describe some of the demographic and reproductive characteristics of this population and to compare them to those located in northern zones. Monthly samples of adults and egg capsules were obtained from October to April and their position was recorded; snails and capsules were gathered for examination in the laboratory. Sex-ratio was near 1:1 for the whole sampling period and the size–frequency distributions were similar for both sexes; females were wider and heavier than males at the same shell length. Maximum shell length was 120.5 mm in our study and so no female reached the minimum size at first gonadal maturity reported for other populations (128 mm); female size seems to limit the capsule diameter and the number and size of embryos that are lower than in other populations. Egg capsule and adult densities in the intertidal zone peaked in February and March respectively, averaging 1.34 capsules and 1.91 snails by 100 m2 during the sampling period; egg capsule deposition elapsed from November to March and peaked in December; females select cobble by size to lay egg capsules. Due to its restricted distribution and the low juvenile and adult dispersal, the unusual Z. dufresnei population dwelling in San Antonio Bay seems to be quite vulnerable to diverse anthropogenic impacts.

Structural adaptations of the mouthparts and digestive tract of four talitrid amphipods were examined in relation to diet, habitat and phylogeny. The species differed in their habitat relative to the shoreline and also in their diet: a 5-dentate ‘sandrunner’, Talorchestia species II (a mid to low shore intertidal diatom feeder), a 5-dentate sandhopper, Talorchestia marmorata (a strandline kelp feeder); a 4-dentate sandhopper, Talorchestia species I (extreme high shore, feeding on spinifex grasses), and a 4-dentate landhopper, Keratroides vulgaris (forest leaf litter, litter feeding). Gross structural characteristics of the mouthparts were similar among all three Talorchestia species reflecting their phylogenetic relatedness. Increased setation and minor structural differences among the Talorchestia species could be attributed to dietary differences, reflecting the zones across the shoreline that they inhabit. Mouthparts of K. vulgaris were elongate, with markedly different setation to the Talorchestia species, reflecting its more distant phylogenetic position and its diet of decaying leaf litter. Digestive tract structure was more conserved among all species due to their phylogenetic relatedness. The gross digestive structure conformed to the general plan exhibited by most gammaridean amphipods. However, an additional pair of lateral pyloric caeca was evident in all species, the function of which is uncertain.

Analyses of the natural abundance of carbon and nitrogen stable isotopes were performed to investigate the feeding habits of two ophiuroids, Ophiomastix venosa and Ophiocoma scolopendrina, and to assess the potential benefit obtained by the symbiotic Ophiomastix venosa juveniles. A tracer experiment was also carried out to clarify the contribution of algae to the nitrogen uptake amongst the tested ophiuroids. Our results suggest that Ophiocoma scolopendrina adults occupy a higher position in the food web than Ophiomastix venosa and mainly feed on neuston. In contrast, O. venosa adults feed on the alga Sargassum densifolium and on organic matter associated with sediment. Free juveniles and symbiotic juveniles of O. venosa have intermediate δ13C values between both adult species. The high proportion of 13C in the symbiotic juveniles compared to the one in their conspecific adults indicates that their diet slightly differs from the latter and is closer to that of Ophiocoma scolopendrina. This raises the hypothesis that symbiotic juveniles steal neuston from their associated host, O. scolopendrina.

The physical characteristics of the Bay having been set out in the preceding paper, it will not be necessary to repeat that description here, since only special local featureswill be dealt with, as occasion arises. Peculiarities of distribution had been noted for the Trochidæ and Littorinidæ, and it was with a view to obtaining further information as to the operation of local littoral conditions and their effects upon the fauna that these grouops were more particularly examined. These notes detail some of the peculiarities, and outline what are believed to the controlling causes, at any rate for the central area of the Bay. It would be of great interest to know whether similar peculiarities have been, or can be, observed for other areas of coast. The region discussed lies between Gwbert-on-Sea at the mouth of the Teifi, to the south; and a point a few miles beyond Pwllheli to the north. The portion more closely examined extends from near Llanrhstyd, some eight miles south of Aberyswyth, to Mochras, a few miles south of Harlech. Some observations were also made about Portmadoc, Borth-y-Gest, and Pwllheli in the northern part of the Bay, and about New Quay, and the mouth of the Teifi the south, the most southerly being some miles below Cemmæs Head.

The sterol biochemistry of the highly advanced molluscan class – the cephalopods – is poorly understood. Few analyses of their component sterols have been published in which GC-MS has been employed (Voogt, 1973; Idler et al. 1978; ApSimon & Burnell, 1980) and these have only involved 5 species.

From the available data the cephalopods appear to have a much simpler sterol make-up than the other less-advanced molluscs. Cholesterol appears to be easily the predominant sterol (ca. 90%) with minor amounts of up to 10 other common marine sterols. Of the species analysed, four (Sepia officinalis, Octopus vulgaris, Eledone aldrovandi and Illex illecebrosus) had a very similar major and minor sterol composition. Only the more primitive Nautilus sp. (Idler et al. 1978) had a noticeably different minor sterol composition.

Voogt (1973) reported cephalopods to be able to synthesise sterols though molluscs generally appear only to be able to carry out this biosynthesis slowly (Goad, 1978). Cephalopods are extremely active carnivores and thus would be expected to have a diverse diet. If their component sterols are of a dietary origin, a considerable variation in their minor sterol composition might be expected on the basis of the range in sterol composition reported for pelagic organisms (e.g. Morris & Culkin, 1977), many of which may be possible dietary components.

Detailed knowledge however of cephalopod diets is limited. Quite apart from the fact that healthy specimens are rarely caught in nets, those that are caught often feed voraciously on the other organisms trapped in the net prior to being brought on board for examination.

The glandular epithelium of both escae and caruncles originates from a solid, branched ingrowth of epidermal cells from the distal surface of the bulb-shaped light gland primordia in the larva. The lumina within the glandular epithelium appear to originate by the breakdown of the central cells within the solid mass of epithelial cells. An epithelium-lined duct connecting the central glandular lumina with the distal surface of the bulb-shaped primordium was seen only in sections of the posterior esca. This suggests that the intraglandular lumina are formed before the duct to the surface, which then develops within an initially solid strand of cells.

The north-eastern coast of Venezuela hosts a high diversity of megafauna, particularly related with high productivity due to coastal upwelling. This area is mainly characterized by the existence of the primary fisheries in Venezuela, mostly supported by a great abundance of small pelagic species. This would explain why the area supports a wide range of marine top predators, including cetaceans. The current status of cetacean populations off north-eastern Venezuela is uncertain, mainly because research efforts have been very sparse. There are still many gaps of information in cetacean biology to establish a solid baseline that can be used for management decisions. Common dolphins (Delphinus spp.) are widely dispersed over the whole north-east basin, including waters off Araya and Paria Peninsula and around Margarita, Coche and Cubagua Islands. Areas of higher densities for Delphinus spp. coincide with the focal location of sardine fisheries and the most-active upwelling on the north-eastern coast. Therefore, a scheme of management should consider the areas of major productivity along the coast as potential critical habitat for the species. Further data collection is recommended, increasing aspects such as trophic ecology and the continuity of behavioural sampling, paired with systematic line transect estimation.

Information regarding spawning grounds of the Atlantic herring Clupea harengus Linnaeus has been based mainly on the collection of spawning fish, newly hatched larvae, or the presence of eggs within the stomachs of predators (Postuma, Saville & Wood, 1977). This type of evidence indicates general areas of spawning, rather than accurately delineating the spawning grounds. Though samples of spawn have been obtained from several localities in the North-East Atlantic (Ewart, 1884; Runnström, 1941; Fridriksson & Timmerman, 1951; Bolster & Bridger, 1957; Parrish et al. 1959; Hemmings, 1965; Bowers, 1969; Anthony, Sauskan & Sigaer, 1970), few quantitative studies of individual grounds have been made. In consequence, little is known of the factors influencing the selection of grounds by Atlantic herring, the shape of these grounds and egg distribution within spawning areas.

Cirrophorus nikebianchii sp. nov. is described from brackish-water and organically enriched marine environments of the Mediterranean Sea. The new species is characterized by a very small prostomial antenna and a high number of branchiae pairs. A phylogenetic analysis carried out through the use of three molecular markers (16S rRNA, 18S rRNA and COI) supports the distinction between C. nikebianchii and C. furcatus, a closely related species with which it has been misidentified. Preliminary results obtained show that the genera Cirrophorus and Paradoneis are not reciprocally monophyletic, with uncertain relationships with the remaining genera of Paraonidae. This outcome suggests that the evolutionary history of Paraonidae is less straightforward than previously supposed. Moreover, the uncertainty about the taxonomic status of Paraonides neapolitana, type species of the genus Paraonides, makes the revamping of the taxonomy of Paraonidae more challenging. Awaiting support from studies including more species, and based on morphological and genetic data as well, we suggest to provisionally maintain the current use of Cirrophorus and Paradoneis, and to assign to Paraonella the species traditionally assigned to Paraonides.