Morbihan Bay, France, is an important spawning area and nursery grounds for young cuttlefish. The eggs and the young cuttlefish are subjected to predatory species of fish. These were identified by analysing the stomach contents of 26 species and two species of cephalopods. Five fish species were found to be predators of young cuttlefish. The Balistes carolinensis feeds on the eggs, and Dicentrarchus labrax, Labrus bergylta, Spondyliosoma cantharus, and Conger conger eat young cuttlefish, from 8 mm (hatching cuttlefish) to 61 mm in mantle length (cuttlefish about 4-months old).

Investigation of the fecundity in Abralia veranyi from the Mauritanian slope showed that potential fecundity of this species is 10,000–26,000 including 1200–2400 (mean 1900) yolk oocytes and ripe eggs. Up to 1000 ripe eggs of 0.7–0.8×0.8–0.9 mm (mean weight 0.30 mg) were found in oviducts. In mated females there were found 13–226 (mean 71) spermatangia. Spawning is intermittent.

Records of the squid (Loligo forbesi) egg masses which were incidentally caught in demersal trawls at three offshore sites are presented. These sites were at water depths of 135, 302 and 507 m. This represents the deepest ever record of spawning in a loliginid squid species. There has been speculation in the literature about offshore spawning in L. forbesi but it has not previously been recorded and may have important implications for the life cycle.

A single maturity classification key applied to five common chaetognath species of the eastern Mediterranean is presented. The efficiency of the key was tested using biometrical data: body length (BL), ovary length (OL) and seminal vesicle width (SVW). For each species the key proved easy to use and efficient in the distinction of the maturity stages providing a satisfactory size separation between them.

The growth bands in the plates of the echinoid Spharechinus granularis settled on the Algerian coast were analysed. Two distinct groups of sea urchins were identified with different growth patterns related to the period of recruitment, i.e. spring or autumn. The growth rate of the autumn cohort was higher over the year following the first winter after settlement. From the second winter there was little growth difference between the two cohorts. Compared to populations from Atlantic sites, the Algerian population has a lower growth rate and reduced longevity.

The reproductive cycle, development and spatial organization of the gonads of an exotic ascidian, Styela clava, were studied in Cork Harbour, Ireland. Monthly histological samples enabled the division of gonad development into six main stages, ranging from `inactive' to `regression'. Gonad development was asynchronous in the population, with more than one stage being found within some months. Gametogenesis was observed from February–November, but peaked between August–October. Spawning took place in September–October, followed by gonad regression in November–December.

Effects of external cation concentrations on larval metamorphosis in the ascidian, Halocynthia roretzi were examined. Metamorphosis (tail resorption) was induced by 20 mM and 50 mM K+ but, interestingly, was suppressed by 30 mM K+. Low concentrations of Ca2+ (1–5 mM) induced metamorphosis, while high concentrations did not, in contrast to findings in other invertebrates. Moreover, BAPTA-AM, an intracellular Ca2+ chelator, induced metamorphosis. This suggests that a decrease in intracellular Ca2+ of certain cells initiates larval metamorphosis in H. roretzi.

A specimen of the oilfish, Ruvettus pretiosus, was captured from the northern Adriatic (Gulf of Trieste) and represents the northernmost extension in range of this species in the Adriatic Sea.

The present study is the first record of twinning in Delphinus delphis. The first foetus was a female of 72 cm total length which had a curved caudal area. This animal was located in the left uterine horn, very close to the genital aperture. The second foetus was a male of 46 cm total length and its external morphology was deformed. It was located in the uterus and the nose was shorter than the female foetus. Documented incidences of twinning in cetaceans are rare.

Histological sections of the gonad of Bathymodiolus azoricus from the Lucky Strike and Menez Gwen hydrothermal vent fields (Mid-Atlantic Ridge) demonstrated a spawning event in this species in May 1994, synchronous between the two vent fields located 60 km apart, and a sexual pause in gametogenesis. As reported for other vent mytilid species, B. azoricus from Lucky Strike and Menez Gwen could exhibit hermaphroditism.