The effect of food concentration on the reproductive success of the copepod Centropages typicus (Copepoda: Calanoida) was studied in the laboratory. Three different regimes of food were tested: absence of food, natural food conditions and a food media enriched with an algal culture. The results showed significant differences in egg production rate between regimes of food, but no significant differences in egg viability. A rapid response (24 h) in egg production rate to increment in the quantity of food was noted. Hatching success was not affected by food conditions prevailing during the incubations.

The first account of mating in a myodocopine using evidence from video recordings is presented herein for Skogsbergia sp. (Cypridinidae). After initial courtship the male and female ostracods, with ventral margins adjacent and anterior ends directly opposite, join their mandibular claws and furcae. Both furcae are pushed in a posterior direction until the ventral margins of the carapace meet. In this position, with genitalia directly opposite, copulation presumably occurs. This mating procedure lasts for five seconds.

Myodocopine ostracods are diverse marine crustaceans occurring world-wide at depths from 0–6000 m (Kornicker, 1975). All myodocopines reproduce sexually (Cohen & Morin, 1990). Some bioluminescent cypridinids (Myodocopina) use luminescent signalling during courtship; males produce species-specific patterns of flashes in the water column to attract females (Morin, 1986). Although myodocopines may be amongst the most abundant macroinvertebrates on the continental shelf (J.K. Lowry, personal communication), they have been the subject of relatively few behavioural studies, and in particular their copulation process is poorly documented (Cohen & Morin, 1990).

Two accounts of myodocopine mating have been reported. In 1914 the cypridinid Vargula hilgendorfii (Muller, 1890) was observed mating in a Petri dish (Okada & Kato, 1949). The male clasped the female using the first antennae while swimming with the natatory second antennae. After 30 to 60 min they rested on their lateral sides, with ventral margins touching and heads facing in opposite directions; the penis (lying between the paired copulatory ‘limbs') was protruded into the female carapace and the spermatophore was transferred. This copulation lasted more than 30 min (Okada & Kato, 1949).

Records of unusual cephalopods, taken as by-catch in Irish and Scottish waters in the years 1985–1995, are presented. Of most interest are three specimens of giant squid (Architeuthis) that were caught in bottom trawls off the west of Ireland between April and June 1995, all were mature males of mantle length ∼1000 mm. Other records include a large mature female Histioteuthis bonnellii from the west of Ireland and three specimens of the gelatinous incirrate octopus, Haliphron atlanticus.

In order to induce metamorphosis in cyprids of the parasitic barnacle Loxothylacus panopaei (Gissler) (Cirripedia: Rhizocephala: Kentrogonida), we tested a number of compounds (ZR-512, 20-hydroxyecdysone, 3-isobutyl-l-methylxanthine and phorbol-12,13- dibutyrate) all known to cause metamorphosis in thoracican barnacles. Only one agent, phorbol-12,13-dibutyrate, had an effect and induced cypris larvae to complete metamorphosis without previous attachment. This suggests that diacylglycerol-activated protein kinase C plays a role in the metamorphosis of kentrogonid rhizocephalans.

Rhizocephalans are highly specialized crustaceans adapted for parasitic life on decapods. The juvenile parasite passes through an internal growth stage, where a root-like trophic organ invades the tissue and haemocoelic fluid of the host (for detailed information on rhizocephalan life history, see Haeg, 1992). As in free-living barnacles, a cyprid larva is the settling stage, and in thoracicans a juvenile barnacle is formed underneath the carapace of the cyprid larva. However, the rhizocephalans develop a so-called kentrogon, which accomplishes the injection of the primordial parasite (Glenner & Høeg, 1995). The degree of specialization towards a specific host means that the cypris larvae of rhizocephalans are extremely selective in their choice of substrata. They will not settle unless a specific host or part of a host, e.g. the gills, is offered. For this reason, the study of settlement and metamorphosis of these species has met with great difficulties.

During the course of a survey into the distribution and growth of the fan mussels Pinna nobilis and Pinna rudis from the coastal waters of the Spanish Mediterranean the presence within the mussels of Pontonia pinnophylax has been recorded. Pontonia pinnophylax typically occurred in adult pairs, but occasionally solitary male individuals were found. The width of the cephalothorax is greater in females than males, whereas the chelae of the second periopods, which are unequal, are larger in males. There is a general relationship between the size of P. pinnophylax and its pinnid host; the largest individuals were found in the largest Pinna and vice versa.

Isolated embryonic membranes (i.e. the outer cuticular membrane, the fibrous layer, the inner cuticular membrane and the hatching membrane) and homogenates of incubated, decapsulated cysts of 16 populations from five Artemia species (Crustacea, Anostraca) were examined by sodium dodecyl-sulphate polyacrylamide gel electrophoresis. Characteristic differences in major polypeptides between 45 and 205 kD were seen. These differences might be used as markers for identification of different Artemia species. The validity of this approach in characterizing Artemia populations is discussed.

The ligament of the bivalve Mya arenaria was previously described as being composed of two layers: a fibrous and a lamellar one, the fibrous layer being more extensive. Other features described, such as the three-dimensional extent of the layers and their mode of attachment to the chondrophores, have been found to be inaccurate to a certain extent. The ligament is therefore redescribed here. It is conical in appearance and attached to the left chondrophore only at its margin, its interior being occupied by an epithelium, which is an extension of the mantle isthmus. The lamellar layer is a pyramidal body which merges into and constitutes the posterior extension of the fibrous layer. The whole structure is internal and may rotate around the dorsoventral axis, thus being suited to allow rocking of the valves. This kind of movement is used when Mya contracts the anterior adductor muscle to eject water from the mantle cavity during burrowing. In this respect the ligament is unique among those known in bivalves.

A detailed analysis of beak length to body length and weight measurements was carried out for the onychoteuthid squid Moroteuthis ingens, in the Falkland Islands region of the South Atlantic. Lower and upper rostral lengths were both good predictors of mantle length and body weight. In addition, the relationships of freshly dissected beaks to mantle length and body weight were significantly different to those of beaks dried before measuring, with dried beaks being better predictors of both variables.

A considerable amount of information on Southern Ocean squid biology has been obtained from analysis of beaks in the stomach contents of predators (Clarke, 1980,1983). Beak analysis can be particularly useful as it provides information on the species preyed upon as well as estimates of squid size and biomass ingested (Clarke, 1983, 1986).

Ferritin crystals and calcium granules are reported from the ventral ceaca of Steleuthera ecoprophycea (Amphipoda: Stegocephalidae) collected from the Snake Pit hydrothermal vent, Mid-Atlantic Ridge (3520 m).

In a series of earlier papers (Moore & Rainbow, 1984, 1989, 1992; Moore et al., 1994), the authors described the widespread occurrence of intracellular, octahedral crystals of ferritin in the ventral caeca of a range of stegocephalid amphipod species from the continental shelf epibenthos and oceanic plankton. The discovery at 3500 m of a new Steleuthera species (S. ecoprophycea), from a hydrothermal vent on the Mid-Atlantic Ridge was announced recently by Bellan-Santini & Thurston (1996), and a complete description is provided therein.

Oceanic ridge sites are notable for their tectonic activity and the presence of a diversity of trace metals at high concentrations is to be expected in hydrothermal plumes emanating from such regions (German & Angel, 1995). The detoxification of accumulated trace metals in the ventral ceaca of stegocephalid amphipods from uncontaminated environments is now relatively well known (see above), so it was of interest to investigate whether a vent stegocephalid showed an atypical presence of trace metals in detoxified form in cells of the ventral caeca. The results following from an opportunity to investigate this are reported herein.

Material was derived from a dive made by the submersible ‘Alvin’ at Snake Pit hydrothermal field, Mid-Atlantic Ridge (23°23′N 44°56′W), 3520 m, on 16 June 1993 (see Bellan-Santini & Thurston, 1996). Steleuthera ecoprophycea was preserved in 70% alcohol. Subsequently to dissection, the single pair of ventral caeca from each of the four damaged amphipods investigated were post-fixed in 4% glutaraldehyde. For electron microscopy and x-ray microanalysis in STEM mode, ventral caecal tissues were then dehydrated through 95% and absolute ethanol, cleared in propylene oxide, embedded in TAAB resin, sectioned at 0·5 μm (semi-thin sections) on a Reichert OmU2 ultramicrotome and examined without staining in a JEOL 100C electron microscope equipped with LINK system EDX energy dispersive x-ray microanalyser.

This short note describes the in situ activity cycles of Galathea squamifera and G. strigosa (Crustacea: Decapoda) through SCUBA diving observations in south-west Ireland. Both species exhibited nocturnal activity peaks, although they were not exclusively nocturnal. Fluctuating tidal current strength and direction had no discernible influence on either species’ activity cycles. It is suggested that shelters, particularly in terms of both predator avoidance and as foraging areas, play an important role in the ecology of both species.

Both the anomuran decapod crustaceans Galathea squamifera Leach and G. strigosa (L.) are widespread throughout the rocky subtidal of the north-west European coastline. In contrast to the general body morphology and the structure of the mouthparts which have been well studied (Nicol, 1932; Pike, 1947), the biology and ecology of the genus Galathea remains poorly studied. These morphological studies have shown that the mouthparts are ill-adapted to living on muddy substrates, essentially restricting the distribution of both G. squamifera and G. strigosa to rocky areas, where their food is obtained by detrital deposit feeding and scavenging. Turner & Warman (1991) have studied the activity patterns of the genus Galathea at Lough Hyne, southwest Ireland and concluded that the genus exhibits nocturnal activity peaks. However, the different species were not distinguished, nor was the potential effect of the aberrant tidal patterns in the area considered. As at least three species (G. squamifera, G. strigosa, G. intermedia) are known to occur at the study site (Holmes, 1985), the present study was initiated to elucidate the activity cycles at a species-specific level.

Four cases of anomalies of the copulatory arm in Sepiolinae (Cephalopoda: Sepiolidae) are reported. In one case (Sepietta oweniana), both dorsal arms were modified resulting in double hecocotylization. In another specimen probably of the same species the copula-tory apparatus was formed by two fleshy multilobed formations situated on the dorsal and ventral side of the arm base. In one specimen of Rondeletiola minor the copulatory apparatus was inversely positioned on the arm base, and in one Sepioh intermedia specimen the inner free portion of the wrinkled tubercle was markedly enlarged.