Mediterranean fish of the Trachinidae and Uranoscopidae families are characterized by a poison apparatus on the 1st dorsal fin. These fish hide by burying themselves in the sand using cryptic mimicry. Nevertheless, if they are discovered before they have completely buried themselves, or perceive a potential source of danger when already covered, they will raise their 1st dorsal fin which has a bright black spot on the inter-radial membrane. We have shown that this black vexillum acts as a threatening visual cue and that the movements accompanying black mark display can be defined as aggressive mimicry.  We therefore thought it interesting to investigate the black mark display in some species of Soleidae, a behaviour never before reported in the literature. In these fish, the black marks are situated on the right pectoral fin which, as a result of the distortion and re-arrangement of some anatomical parts during development, shifts to a dorsal position in adults. Soles also bury themselves in the sand, and they too display their marked fins on the approach of a possible predator, just like fish belonging to the above dangerous families.

Adults of the isopod genus Holophryxus (Dajidae) occur as ectoparasites on natant decapod crustaceans, but little is known of the ecology and life-history of most species. Species of Holophryxus are thought to have a typical dajid life cycle involving an intermediate host (copepod), a definitive host (prawn) and three larval stages (epicaridium, microniscus, cryptoniscus), and the one species for which details are available fits this pattern (Coyle & Mueller, 1981). The final host is infected by the cryptoniscus, a stage superficially resembling a cirolanid isopod, and the first cryptoniscus to settle loses its isopod-like appearance and develops through a juvenile stage into a rather inflated, highly modified female (Coyle & Mueller, 1981). Any subsequent settler becomes a male, retains the small cryptoniscus body form and lives within the marsupium of the female.

The Iberian Peninsula is part of the South European Atlantic Shelf within the Lusitanian ecoregion. Given the characteristics of this region, a great invertebrate biodiversity is expected. Nevertheless, no literature records of Polycladida are known for the Cantabrian Sea. Here, we report the presence of six polyclad species, including one new species. Notoplana vitrea, considered endemic to the Mediterranean Sea, was found in the Cantabrian Sea, demonstrating its presence in Atlantic waters. This species was previously reported for these waters on two natural history photographic websites: the importance of searching, indexing and disseminating this type of record for the scientific community is discussed. Discocelis tigrina is reported for the first time for the Cantabrian Sea, and is the northernmost record to date. In this paper, Pleioplana atomata is reported for the second time for the Iberian Peninsula, yet is the first record for the Cantabrian Sea. Although a literature record of Leptoplana tremellaris for the Iberian Peninsula exists, it is considered a misidentification of L. mediterranea; therefore, this work provides the first record of L. tremellaris for the Iberian Peninsula. The cosmopolitan species Cycloporus papillosus is also reported for the Cantabrian Sea. A new species, Imogine fafai sp. nov., is described and taxonomically compared with other species of the genus.

Six hundred and seventy nine specimens of Platichthys flesus (L.) were caught in summer (July–September) 1998 and 1999 from three regions of the Polish zone of the Baltic Sea: the Gulf of Gdańsk, the Pomeranian Bay and the open sea off Łeba. The biometric measurements (length, weight, age) and sex of the specimens were recorded. The specimens were examined for occurrence of parasites. The intensity, relative density and prevalence of infection were calculated.

In direct-transfer temperature tolerance experiments, Lasaea rubra was found to have a median lethal low temperature of – 3.5°C and a median lethal high temperature of + 39°C. If introduced to temperatures slowly, survival at extreme temperatures was improved, particularly at freezing temperatures; > 92°0 of animals survived at – 10 °C and + 40 °C if introduction from a holding temperature of + 18 °C took place over at least 1 h.

Lasaea rubra are active at salinities between 15 and 60‰, indicating considerable tolerance of changes in body fluid osmolarity. In week-long exposure experiments more than 50 % of animals survived all salinities from 0 to 150‰; tight shell valve closure was maintained at extreme salinities.

When exposed to declining salinity, Lasaea rubra progressively isolates its tissues from the environment as salinities fall below 18–20‰, and maintains shell valve closure below 8‰. These responses are symmetrically reversed in response to rising salinity.

Salinity discrimination in Lasaea rubra is based upon sensing of external osmolarity, not external ionic concentrations.

In studies carried out off the north-eastern and south-eastern coast of Brazil, three species of Prosphaerosyllis were found: P. isabellae, which was already recorded for Brazilian waters; P. xarifae, a newly recorded species for the area; and P. brachycephala sp. nov., a new to science species. Prosphaerosyllis brachycephala sp. nov., is characterized by having swollen anterior part of the body, prostomium retractable within the peristomium and anterior segments, short antennae, short peristomial and dorsal cirri, and falcigers with short, unidentate blades throughout. All these species are herein described and compared to the most similar congeners.

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.

During July 1984, large numbers of the sandy beach bivalve Donax vittatus (da Costa) were found either stranded in the intertidal, or washing to and fro in the surf on beaches at Dornoch, on the east coast of Scotland. The affected bivalves all carried large growths of several species of algae. The normal burrowing and recovery responses of the bivalves were unable to overcome the increased drag resulting from these epizoic algal colonies so that wave action caused dislodgement from the sand and eventually, stranding and death from dehydration. The resulting mortality affected mainly older individuals in the population; younger individuals had very small or no attached algae and were not dislodged.

The algal growths were complex and showed three stages in their development: primary settlements formed generally short tufts or mats attached to the posterior tip of die shell; secondary ‘dominant’ species were also attached to die shell but formed larger growths; tertiary species were attached as epiphytes to the primary and secondary growths. At least eight species of algae were involved. Juvenile mussels (Mytilus edulis L.) were also present in many cases attached to the weed, adding further to die drag.

During 1985, at Dornoch, secondary and tertiary algal species developed progressively from overwintering primary settlements, but the size of die algal colonies which developed was generally smaller dian in 1984 and diere was apparently little dislodgement and mortality.

Donax vittatus populations on other beaches in die Moray Firdi, and on most other Scottish beaches examined, had fewer individuals with attached algae, and diose affected carried only relatively small colonies which did not prevent normal burrowing. Complex algal colonies, showing even greater species diversity than those of Dornoch were, however, found on D. vittatus on beaches in South Harris, Outer Hebrides, during September 1984.

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.

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.

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.

The accepted accounts of the excretory organs of the Decapod Crustacea are based chiefly upon the investigations of those numerous observers who have studied Astacus fluviatilis ; the only recent memoir which attempts to deal with the arrangement of this system of organs in any other genus being the well-known work of Grobben.

1039 flounders were marked with numbered vulcanite disks in the estuaries of the Tamar and Lynher.

148 flounders were recaptured and of these seven fish were recovered a second time after one recovery and release, and one fish was recaptured on three occasions after two previous recoveries and releases.

Only two fish were recovered at a distance from Plymouth. Both had moved eastward, up the English Channel.

There was little or no growth in the winter months.

Individual growth rates were found to vary greatly.

The flounders living in the last reach of the Tamar near Saltash tended to remain in one limited area during the winter months, save for a drift down-stream of some of the larger fish. In the spring there was an upstream movement of the smaller, immature fish.

Flounders which had gone down to the sea to spawn might return to the river in which they were marked, or to the other river of the two which join to form the Hamoaze, or they might move right away from the area where they were marked.

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.

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.

Using a large passenger cruise-ship (MV ‘Discovery’) as a platform, a cetacean survey was conducted between 1 August and 3 September 2005 across the northern North Atlantic Ocean and back, covering waters between the UK, Iceland, Greenland and Canada. The objective was to collect sightings data for all cetacean species encountered to begin to collate information for a large-scale sightings database. Two observers employed standard-distance sampling techniques and visual observations (naked eye) to scan for cetaceans during daylight hours and favourable weather conditions. Approximately 112 h were spent surveying over 23 d. A total of 13 cetacean species were encountered, with 173 separate sightings recorded, totalling over 2000 animals. The most commonly sighted species were minke whales (Balaenoptera acutorostrata: N=44), Atlantic white-sided dolphins (Lagenorhynchus acutus: N=34, with group sizes of up to 600), and humpback whales (Megaptera novaeangliae: N=31). The distribution of minke whales, Atlantic white-sided dolphins and fin whales was linked to underlying oceanographic variables. Overall patterns of distribution were consistent with our understanding of the summer distributions for the species encountered. The survey highlighted the cetacean diversity of the northern North Atlantic region. Repeat work using this methodology will allow an examination of species' distributions and estimation of their relative abundance.

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.

Reliable methods to identify and monitor cetacean individuals are important to assess population behaviour and ecology. We describe and evaluate the application of the digital video-identification technique (DVI) for the acquisition and analysis of dorsal fin images in the study of bottlenose dolphins (Tursiops truncatus) in the Cagarras Archipelago, Rio de Janeiro, Brazil. Between August and November 2004, we identified and catalogued 20 individuals; 80% were re-sighted more than twice. The Individual Residence Index varied between 1.0 (N = 1) and 0.2 (N = 4). Compared with traditional photo-identification methods, DVI offers significant advantages in respect to production of sequential images and speed of editing and processing.

In the Bay of Seine (English Channel) the polychaete Pectinaria koreni exhibits interannual stability in its abundance, despite its isolated distribution and its bentho-planktonic life cycle. To test the hypothesis of a high level of recruitment related to high survival rate of the post-larvae due to metamorphosis in the water column (transformation of metatrochophore into aulophore), we undertook a study of the morphology and the dynamics of the aulophore stage during May and June 1987. The morphological study snowed that aulophore larvae do not possess all the morphological features needed for benthic life on their first contact with the substratum. Fifteen days are needed to complete this development, and during this time the mortality rate is high. The possible role of this delayed metamorphosis on the transport of aulophore larvae towards sites favourable to adults is also discussed.

Six new species of Hexactinellida are described from hard bottom communities of shelf, canyon and seamounts of the west coast of North America: Washington, British Columbia and Gulf of Alaska. They were collected by a variety of methods, trawl, manned submersible, and robot submersible, and hence vary greatly in condition. The six species comprise additions to five different families of the subclass Hexasterophora, Farreidae (Farrea omniclavata sp. nov. and F. truncata sp. nov.), Euretidae (Chonelasma oreia sp. nov.), Euplectellidae (Amphidiscella lecus sp. nov.), Leucopsacidae (Oopsacas olympicus sp. nov.) and Rossellidae (Acanthascus malacus sp. nov.). These additions represent an increase of 29% to the known species of Hexactinellida in this area. A completely unique form of defended tabulate stalk is described for A. lecus. The species Chauoplectella spinifera is transferred to Oopsacas.