Prevalence of the parasite Hemioniscus balani (Isopoda: Cryptoniscidae) was determined in intertidal barnacles Semibalanus balanoides collected from north-east England during winter 1989–1990 and March 2000. Infection by female and male stages of the parasite were low (0·0–13·6% and 0·0–9·9%, respectively). Female stages were usually more prevalent lower down the shore, and were more common among larger barnacles. The observed rates of parasitism are similar to those recorded in the region 40–50 years ago.

Five specimens of the penaeid genus Funchalia were found inside living Pyrosoma atlanticum taken off Tenerife. No such association has been noted previously. The largest of the Funchalia was an immature F. villosa; the other four were early post-larvae. Aspects of their morphology are described and compared with previous descriptions. They were probably also F. villosa.

Haloes of encrusting algae, mostly Hildenbrandia, and cyanobacteria were found on the home scars under the shell of Patella vulgata, beneath the pallial cavity. The presence and area of halo varied between sites. Area generally increased with limpet size and at one site was negatively associated with slope of the shore. It is suggested that the algae provide a resource and may, therefore, play a role in the foraging ecology of the limpet.

Stable carbon isotope measurements (δ13C) were used to assess the sources of carbon assimilated by the fan mussel Pinna nobilis, in sea grass Posidonia oceanica meadows, and an associated shrimp Pontonia pinnophylax which occurs within this bivalve's mantle cavity. The primary carbon sources available to both animals displayed a wide range of δ13C values, from −12·3 to −22·3‰. The δ13C and δ15N of Pinna nobilis and Pontonia pinnophylax suggest that they assimilate carbon from similar sources, occupy comparable trophic levels and that their association is commensal.

Geostatistical analysis was used to investigate the effect of drift kelp on the spatial distribution of the sea urchin Tetrapygus niger. The positions of all sea urchins were mapped in four experimental plots in the rocky intertidal zone of the central Chilean coast. When drift macroalgae were added, the sea urchins left the substratum irregularities, increased in number inside the experimental plots, and tended to form a dense aggregation around the kelp. After the drift macroalgae was removed, the aggregations disappeared and the sea urchins returned to the depressions and/or interstices of the substratum. The results suggest that the influx of drift kelp is the triggering factor in the formation of dense aggregations of this species.

Sex reversal is common in the animal kingdom, yet nothing has thus far been known about it in amphioxus. The present study showed that female amphioxus reared in the laboratory was sexually reversed into the male, but not vice versa. This is the first report on the existence of sex change in the cephalochordate.

This is the first report on the presence of basking sharks Cetorhinus maximus in Galician waters (north-west Iberian Peninsula) from sightings, strandings and incidental catches by fishing gear. Morphometric, biological, geographic and temporal data on 19 basking sharks recorded from 1988 to 1998 are presented. Average total length is 401·4 cm. Male:female ratio is 0·6. Seventy per cent of records are from incidental fishing catches in bottom gill nets. Approximately 74% of sharks were recorded during February, March and April, which may suggest that the species occurs seasonally in this area.

In summer 1997, the stomach contents of 235 red pandora collected by bottom trawl from Hisarönü Bay in the southern Aegean coast of Turkey, were analysed. It was observed that red pandora is predominantly a diurnal feeder. More intensive feeding started in the afternoon, reaching its maximum value in the evening and continued until dusk. The minimum feeding intensity occurred during the night. The diet was found to consist primarily of polychaetes, especially Glyceridae, and crustaceans, mainly Natantia. No significant diel variation was observed in the diet composition of red pandora.

There is sometimes a significant bias in the sex ratio of fish caught by longline. Usually, more females than males are caught. The possible reasons for unequal sex ratios in longline catches are listed and discussed. One sex could be more common in the area where the fishery takes place because there really is an unequal sex ratio in the population or because the other sex preferentially occurs in different places. Alternatively, longline fishery might preferentially catch one of the sexes. This could be a result of size difference between the sexes and thus a different response to the given hook size or bait size. Finally, sexes could differ in their feeding behaviour. There is growing evidence that females—not only of fish—are ‘energy maximizers’: they find food faster and spend more time feeding than do males. Thus, fishing methods using bait are likely to catch a higher proportion of females than fishing methods that do not use bait.

Minke whale (Balaenoptera acutorostrata) surfacing intervals were recorded over a period of three years in the coastal waters of Mull, Coll and the Small Isles, in the north-west of Scotland. Significant differences in surfacing intervals were noted both throughout the day and throughout the year. Surfacing intervals were shortest at noon and in the months of June and July. Surfacing intervals were longest both mid-morning and mid-afternoon and during May and August. Differences in surfacing intervals were interpreted to be the result of ecological changes such as different foraging strategies. Consequently, the results of this study have an impact on the methodologies and designs of minke whale sightings surveys.