Virus-like particles (VLPs) were observed in thin sections of the plumose anemone, Metridium senile, collected from seawater off the west coast of Sweden in 1969. The VLPs were observed in the nucleus of spiroblasts and amoebocytes; they were either pentagonal or hexagonal in section, indicating an icosahedral structure. Virus-like particles were ∼60 nm in diameter, with an electron-dense core 40 nm in width; they had no apparent tail. This is the first substantial report of viruses observed in sea anemone cells.

A specimen of the deep-water, spatangoid urchin, Cystochinus loveni, wearing a costume of agglutinated protists, was collected from 3088 m in the Gulf of Alaska, north-east Pacific. Over 24 putative taxa of living and dead foraminiferans and xenophyophores, as well as a sipunculan, polychaete, tanaid, and two isopods, were collected from the dorsal surface of this single individual. This is the first report of a deep-sea urchin using rhizopod protists and it is proposed that the urchin acquires camouflage or benefits from increased specific gravity associated with the protistan cloak.

Current flow regime, bathymetry and substratum angle were found to influence the density and distribution of the following anthozoan species at Lough Hyne Marine Nature Reserve, Ireland: Corynactis viridis, Alcyonium digitatum, Caryophyllia smithii, Anemonia viridis and Anthopleura ballii. Density variation was found on inclined, vertical and overhanging cliff surfaces for species found on hard substratum (Corynactis viridis, Alcyonium digitatum and Caryophyllia smithii). All species showed significant variation with increasing depth and between sites with different water flow rates.

 A feeding experiment was conducted on the marine worm Nereis diversicolor to compare the fate of a hydrocarbon mixture during the gut passage in this species with the hydrocarbon breakdown process demonstrated for Nereis virens. Hydrocarbon dissolution/solubilization processes in the gut of N. diversicolor were found to have similar qualitative and quantitative importance in the hydrocarbon transformation as those observed in N. virens.

This study was conducted to research brachyuran crabs at the upper infralittoral zone of the Dardanelles from August 1997 to February 1998. The samples were collected by diving and dredge. The crabs were fixed and preserved in 5% formalin prepared in seawater. The brachyuran crabs were identified in systematic order according to literature records and data.

It was established that eight discernible species and eight genera belonging to five families on the shores of the Dardanelles existed, including: Eriphia verrucosa, Xantho poressa, Carcinus aestuarii, Liocarcinus depurator, Maja crispata, Pachygrapsus marmoratus, Ilia nucleus and Macropodia longirostris.

The astigmatid mite species, Tyrophagus putrescentiae, was found to occur in meiobenthic collections from the Mdloti Estuary on the eastern seaboard of southern Africa. To examine whether these mites are actually components of estuarine systems or the result of contamination of collecting and laboratory materials, special sterilization procedures were incorporated into the collection protocol. Samples employing sterilization procedures still yielded Tyrophagus mites, providing evidence for their existence in the estuarine sediments. The origination of these mites in estuarine and fringe marine systems, in general, is discussed. These findings are significant in terms of the potential trophic importance of Tyrophagus mites.

At the period of sexual reproduction of the rhizocephalan parasite, Sacculina polygenea, the sacculinized crab, Hemigrapsus sanguineus, can serve as a temporary carrier for juvenile bivalve molluscs, Mytilus trossulus and Hiatella arctica as facultative epibionts. Such epizoans are never found on the crabs without the rhizocephalan externae or scars produced by the externae. The correlation between sacculinization and the bivalve epibionts is presumably due to maternal ‘brooding care’ with altering grooming behaviour of the crabs infested by S. polygenea.

Loripes lucinalis, a small bivalve belonging to the Lucinacea superfamily living in reducing coastal sediments, possesses chemoautotrophic sulphur-oxidizing bacteria in its gill. Here, a population of putative sulphur-oxidizing bacteria is described colonizing the bivalve's inner periostracal secretion. The bacteria were particularly abundant in the vicinity of the anterior and posterior inhalant syphons. Most of the bacteria observed were oval to rod-shaped and measured 3·9±1·2 μm on average. Histology and negative transmission electron microscopy staining revealed that these bacteria contain refractile spherules similar to those seen in the endocellular gill symbionts of L. lucinalis.

Length–weight relationships were estimated for 18 Red Sea immigrant fish species from the eastern Mediterranean coasts of Turkey. The values of the exponent b in the length–weight regression (W= aLb) ranged between 2·482 and 3·355. The median value was 3·018 and 50% of the values ranged between 2·835 and 3·121.