To characterize the ultraviolet (UV) light-absorbing function of the ascidian tunic, the light absorption spectrum was compared in 22 ascidian species collected from tropical and temperate waters. Non-photosymbiotic ascidians (17 species) had transparent tunics transmitting both visible and UV light, or pigmented or opaque tunics equally absorb both UV and visible light. However, a prominent absorption peak around 320 nm was exclusively found in the colonial ascidians hosting the algal symbiont Prochloron sp., and this absorption peak corresponded to absorption of UV-A (320–400 nm) and UV-B (280–320 nm). The UV-absorbing substances were extracted with methanol. They were mycosporine-like amino acids (MAAs): mycosporine-glycine, palythine, shinorine, and porphyra-334. The MAAs are thought to be synthesized by the shikimic acid pathway that does not occur in animals. Since the isolated Prochloron cells contain MAAs, the symbionts are the most possible candidates as the source of the MAAs in the tunic. In Diplosoma virens, the composition of MAAs was different between isolated Prochloron cells and colony residue from which Prochloron cells were extracted.

Age, growth and reproductive parameters related to the marine tucuxi are presented, as well as feeding habits and parasitism. The specimens' age ranged from zero (newborn) to 21 years for males and 0·5 to 30 years for females. In relation to the body dimension, length distributions were bell-shaped for both sexes with male marine tucuxi ranging from 86·0 to 200·0 cm in length and females from 117·5 to 198·0 cm. The body length of new-born and calves varied between 86·0 to 117·5 cm and the postnatal growth curve an asymptotic reached length of 191·0 cm. According to the relationship between age, body length and reproductive characteristics, male and female specimens were considered sexually mature when [ges ]6 years and body length [ges ]180·0 cm and [ges ]6 years and body length [ges ]160·0 cm, respectively. Males and females up to six years old represented around 80% of the captures, indicating a bias towards juveniles and individuals that have yet to reach sexual maturity. The youngest specimen with solid contents in the stomach was 119·0 cm in length and seven months old. The marine tucuxi feeds on neritic prey, preferentially on the teleost fishes Trichiurus lepturus and Porichthys porossisimus, and on the cephalopods Loligo sanpaulensis and L. plei. Back calculation of prey lengths indicated that fish ranged from 1·2 to 106·9 cm and cephalopods from 3·4 to 22·2 cm. The barnacle Xenobalanus globicipitis was recorded attaching to the caudal fin and the helminths Braunina cordiformis, Anisakis typica, Halocercus brasiliensis and Nasitrema sp. were found in the internal organs.

Competent larvae of the commercially important marine gastropod Concholepas concholepas (Gastropoda: Muricidae) ‘loco’, were collected in the field and exposed in the laboratory to adult conspecific shells with and without barnacle epibionts. Settlement and metamorphosis was induced by the presence of barnacles on shells of live or dead conspecifics, but not by C. concholepas shells without barnacles. Results from laboratory experiments agreed well with field surveys showing the presence of recruits on conspecific shells overgrown with barnacles in shallow subtidal habitats (∼3–30 m deep), suggesting the potential importance of barnacles in inducing settlement and metamorphosis of locos under natural conditions. Most loco recruits were found below the C. concholepas shell apex, feeding on barnacles, inhabiting crevices among them, and inside dead barnacles. The mean size of recruits on locos' shells increased over four months from the beginning of the settlement season and no individual larger than 1·5 cm was observed, suggesting that they abandon adult loco shells at this size, roughly 5–6 months after settlement.

In this study randomly amplified polymorphic DNA (RAPD) fingerprinting is proposed for species identification of Gammarus, based on the electrophoretic position of amplified DNA bands. Three common marine amphipods of European estuaries—G. chevreuxi, G. insensibilis and G. locusta—were profiled using ten RAPD primers, accompanied by a careful morphological identification. Nine of these primers produced a very distinct species-specific RAPD profile, allowing unambiguous differentiation of amphipod species assayed. The RAPD fingerprints were here characterized by 8–12 amplicons for each primer. Each amplicon was visualized as a band of known molecular length, with characteristic band thickness and density. A total of 78 diagnostic bands, based on the most robust and evident amplicons found for each primer and species, are proposed for identification of the Gammarus species analysed. These results allowed us to identify an unknown amphipod species from a previous study as G. insensibilis, only based on the RAPD fingerprint. One primer was sufficient for this identification. A taxonomic identification system integrating molecular and morphological tools is proposed for Gammarus.

The occurrence of barnacles and crabs on Caretta caretta specimens found in the waters around Italy was analysed. In the seas surrounding Italy balanomorph barnacles occur mainly on turtles frequenting shallow waters and crabs display a strong west–east gradient. Patterns of turtle distribution and movements are proposed. The abundance of turtle-specific barnacles may be dependent on, and so an indicator of, turtle density.

Age and growth of Todarodes sagittatus were estimated based on statolith analysis from individuals (N=352; 81–418 mm mantle length) caught by bottom trawlers during a year of sampling in the western Mediterranean. The daily nature of statolith increments was indirectly validated comparing the mean age of consecutive monthly modes (identified on the monthly length–frequency distributions) with the corresponding increase of 30 days. In agreement with other ommastrephids, results confirmed the following points: (1) lifespan lasts nearly a year; (2) growth rates decrease with age; (3) when adult, females have higher growth rates than males; and (4) females mature about a month later than males. Significant correlation was found between hatching (which occurred throughout the year but with a peak in November) and temperature at 50 m depth (where it is thought that hatchlings inhabit). Age and growth results were compared with those obtained in a similar work carried out in north-west Africa (Arkhipkin et al., 1999). Comparisons suggested that due to higher growth rates in juveniles, southern populations reach maturity and consequently decrease somatic growth at younger ages and smaller sizes than northern squid, which attain larger sizes as a result of maintaining fast growth and delaying maturation. Greater growth rates in juveniles from west Sahara could be explained by higher temperatures in this area than in the Mediterranean.

Three specimens of the spider crab, Maja goltziana, were caught from the southern Adriatic (Mljet Island) and represent the first record of this species in the Adriatic Sea.

A review of the verified reports to date of Architeuthis spp. showed that 33·9% (115 specimens) of worldwide reports were derived from the north-eastern Atlantic. The sex of each specimen, nature of the report, as well as the season and area of collection are presented. Biological data are presented on the two first males of Architeuthis sp. captured off the Iberian Peninsula. The first male (42 kg and 98 cm mantle length) was caught at 43°54·26′N 5°29·38′W by pair trawlers on 13 September 2002. Spermatophores ranged from 11 to 20 cm in length. The peculiar observation of other spermatophores embedded in the skin near the proximal part of the ventral, ventro-lateral and dorso-lateral arms is discussed. The second male (66 kg and 122 cm mantle length) was found floating on the surface off Gijón on 16 September 2003. Although mature, no spermatophores embedded in the skin were observed. A comparison was undertaken of several morphometric measurements between these two males and five other north-eastern Atlantic males from which data were available.

A 6·1-m long female basking shark (Cetorhinus maximus) was tagged 73 km east of Nantucket Island, Massachusetts on 27 September 2001 with a pop-up archival transmitting tag. The tag detached prematurely on 6 December 2001 in an area approximately 800 km south-west of the tag site off the coast of North Carolina. The basking shark was vertically active for the 71-d tracking period, moving through depths and temperatures ranging from the surface to 320 m and 5·8 to 21·0°C, respectively. The shark displayed temporal variation in its residence depth and exhibited a marked temperature preference, with 72% of the temperature observations between 15·0 and 17·5°C. This track provides evidence that the basking shark associates with the continental shelf and shelf edge off the south-eastern United States during autumn. Moreover, it corroborates previous studies indicating that the basking shark remains active and does not hibernate during autumn.

Amphipoda belong to the most abundant benthic organisms of Antarctica, the Epimeriidae being one of the most dominant families. Morphological characters are used to explore relationships between the species of all Antarctic Epimeria, the genus representing 70% of Antarctic epimeriid species. Additional Epimeria from the deep sea off Brazil, the Tasman Sea and from shallow Norwegian waters are analysed. Species of Epimeriella and Metepimeria, as well as iphimedoid taxa are also considered.  High intraspecific variation was observed, which was not related to size, sex, or locality and may indicate recent speciation of some Antarctic epimeriids.  The small number of taxa studied from the deep sea and the northern hemisphere and difficulty in defining apomorphic and plesiomorphic states does not allow us to present final conclusions about the origin of Antarctic Epimeria living on the Antarctic shelf. Nonetheless, deep-sea species from the mid-Atlantic form a clade with deep-sea species from the western Pacific and two of the three studied North Atlantic species. This supports the Watling & Thurston (1989) hypothesis that Antarctica acts as an evolutionary incubator.

An assemblage of shallow-water fish was sampled with a small beach seine over monthly 24-h periods between April 2000 and March 2001 at the sandy beach Duće Glava in the eastern Adriatic. Monthly sets of samples were divided into day and night catches to examine the stability of diel differences in assemblage structure over a 1-y period. A total of 61 species was caught, of which six were exclusively diurnal and 12 were nocturnal. According to abundance and biomass of individuals during day and night, the most abundant species were categorized into several groups. Ophidion rochei was exclusively nocturnal, while Nerophis ophidion and Echiichthys vipera were mostly nocturnal. Diplodus annularis and Mullus surmuletus were slightly nocturnal. Diplodus vulgaris, Pomatoschistus marmoratus and Atherina boyeri lacked a diel pattern. Sardina pilchardus, Lithognathus mormyrus, Atherina hepsetus, Sarpa salpa and Mullus surmuletus abundance peaked for a few months, probably related to timing of spawning and recruitment. At the assemblage level, the diel per cent similarity index indicates that there were major differences between the day and night assemblages in April, September, March, and August with respect to number of individuals and September, October, May and March with respect to biomass.

Thylacoplethus isaevae, a new species of colonial rhizocephalans, is described from the hermit crab Pagurus trigonocheirus collected in the Sea of Okhotsk, along the coast of Sakhalin Island. The new species differs from other known species of Thylacoplethus by the presence of complex spermatogenic bodies located within the mantle and the significantly larger size of its externae.

The influence of two sea-cage fish farms at Gran Canaria Island (Canary Islands, central east Atlantic Ocean) on the intertidal macrobenthic assemblages was studied. Two controls and two impact locations were established at each farm. The composition and coverage of the macrobenthic assemblages were surveyed every three months using image processing analyses. Significant dissimilarities were found between control and impact locations at both sea-cage fish farms. The presence of: (1) algal species tolerant to pollution (Caulerpa racemosa and Corallina elongata); and (2) filter-feeding fauna (Anemonia sulcata) at impact locations, indicate that the fish farming activity is causing an effect on the surrounding intertidal macrobenthic assemblages of both sea-cage fish farms.

The morphogenesis and cytogenesis of the salt gland was studied in various embryonic stages of the viviparous Oman shark, Iago omanensis, from the Gulf of Aqaba, Red Sea. The primordium of the gland is revealed in embryos of 18 mm total length (TL) as a protrusion of the gut posterior to the spiral valve, enveloped in the peritoneal epithelium. In 30 mm TL embryos the glandular parenchyma begins to be organized into secretory tubules extending radially and opening into the central canal of the gland. From this stage on the developments include: thickening of the gland capsule and formation of internal lobules by extensions of connective tissue; strong amplification of the basolateral cell membranes of secretory cells into the cell-cytosols; enlargement of the gland by hypertrophy and hyperplasia of the ion-transporting cells. In 65 (±5) mm TL embryos the gland closely resembles that in adult fish and in pre-term juveniles of 165 (±5) mm TL the gland in general morphology and cytology is identical to that of adults. The results demonstrate that at time of liberation into the environment the juvenile of Iago omanensis is provided for osmoregulation with a functional gland.

During a recent survey of the biodiversity of shallow-water aphotic marine caves of Madeira Island (north-east Atlantic), 12 specimens of the rare deep-sea shrimp genus Bresilia (Caridea: Bresiliidae) were collected from a depth of 15 m. The collected shrimps are described and illustrated as Bresilia saldanhai sp. nov., increasing to five known species of the genus. Morphological characters are compared and discussed, and an updated world key for the genus Bresilia is presented. For the first time, a species of this poorly known genus can be described from a significant number of intact specimens. This occurrence once more demonstrates the strong environmental similarities and evolutionary ties between marine caves and the deep sea.

Data on age and reproduction of the rabbitfish at the Portuguese continental slope are presented. Ages were estimated based on transverse sections of the dorsal spine. Differences in growth patterns were detected between sexes—males grow slower and are smaller than females. The results from histological analysis of different development stages of testes indicated that the macroscopic scale used is well adapted to rabbitfish sampled in Portuguese waters. In females and excluding macroscopic Stage 4, which according to the adopted scale corresponds to an active phase, all the remaining stages were identified in the samples. Ovarian fecundity was estimated as 6·46±2·32 oocytes (females range: 45·0 to 70·0 cm pre-supra caudal fin length [PSCFL]). Length of first maturity in males (40·7 cm PSCFL) is lower than in females (45·9 cm PSCFL).

Two inshore rocky subtidal sites on the west coast of Scotland (Saulmore Point, Firth of Lorn, 056°27′N 005°24′W and Davy's Rock, Firth of Clyde, 055°46′N 004°53′W) were surveyed for the presence of juvenile (0+) Atlantic cod, Gadus morhua between September 1995 and November 2001. A total of 951 juveniles were recorded at Saulmore Point and 34 at Davy's Rock. At Saulmore Point the abundance was highly seasonal, being observed between June and December only. Juveniles were present in only three out of six survey years, with a maximum abundance of 0·89 individuals m−2 recorded in 1996. Maximum abundance of juveniles at Saulmore Point was negatively correlated with winter seawater temperature, indicating that winter temperatures may be a useful indicator of subsequent juvenile abundance levels in inshore habitats.