The embryology of amphioxus (Chordata: Cephalochordata) has features in common with vertebrate embryology, reflecting a close phylogenetic relationship between the two taxa. Amphioxus differs from vertebrates, however, in having less complex organogenesis and cranial morphogenesis, and less specialization along the anteroposterior body axis. Here we illustrate this by describing the embryology of an amphioxus species, Branchiostoma floridae. To gain further insight into the origins, evolutionary divergence and comparative embryology of these taxa, we are comparing the molecular control of embryonic development in amphioxus and vertebrates. For these analyses, we are focusing on homeobox genes: a diverse multigene family implicated in developmental control in many Metazoa. We report the results of PCR-based experiments which reveal that the amphioxus genome has homeobox genes from several recognized gene classes. The PCR experiments also suggest that amphioxus has fewer ‘Hox’ and ‘Msx’ class homeobox genes than do vertebrates. We suggest, therefore, that amphioxus may be a living descendant from an intermediate stage in the evolution of homeobox gene family complexity, and the complexity of vertebrate developmental control. The pattern of gene expression during embryogenesis has been described for one amphioxus homeobox gene of the Hox class. This gene is primarily expressed in the presumptive neural tube of amphioxus neurulae, later embryos and larvae, in a spatially-restricted manner. The expression data lead us to suggest that Hox genes are involved in the control of spatial patterning in the neural tube of amphioxus; the data are also interpreted as giving insight into possible homology between the amphioxus and vertebrate body plans.

Data collected over a period of 15 years for lobsters maintained at 10 °C and weighingfrom < 1·0 to 1200 g have been analysed. Equations have been produced defining the relationships of the cast shell weight, the growth increment at the moult, the inter-moult period and the food intake per moult with the weight of the lobster, and of the growth increment with the food intake. In particular, a growth curve has been derived showing the weight of lobsters, kept at 10 °C, with age. It is suggested that when there is an adequate food supply, the growth increment is a constant proportion of the lobster weight, and that variations in growth rate are achieved by changes in the length of the inter-moult period which, in turn, is mainly dependent upon the temperature of the environment.

During a short visit to Plymouth, in 1928, Dr. M. W. de Laubenfels made a collection of sponges which, with the exception of six, he identified and deposited in the Biological Laboratory at Plymouth. Before leaving England he left these six with me, with the request that they should be identified. This I have now done, and the results have proved extremely interesting, adding six species, Halichondria bowerbanki, Mycale similaris, Iophon hyndmani, Endectyon delaubenfelsi, Hymedesmia stephensi, and Pachaxinella subdola, to the recorded faunal list for Plymouth, of which three are new species.

Callista chione is the most prominent suspension-feeding bivalve species inhabiting the soft bottoms of the Bay of Banyuls-sur-Mer. Ingestion rates and absorption efficiencies when fed monospecific cultures of either phytoplankton (Pavlova lutheri) or bacteria (one natural strain isolated from the marine environment) were determined using 14C radioactive pulse–chase feeding experiments. Microalgae were ingested at a rate five to six times higher than bacteria (i.e. 2.31×10−3 against 0.40×10−3 mg DW mg SFDW−1 h−1). Such differences were attributed to differences in average particle sizes. Bacteria were also less absorbed than microalgae (i.e. 64.3 vs 83.8%). Together with existing data regarding the ratio of free to attached bacteria in the oceanographic environment, these results suggest that free bacteria probably contribute to meet only a small portion of the energy requirements of adult C. chione populations.

The blackmouth catshark, Galeus melastomus presents a wide Atlanto-Mediterranean distribution, and is commonly captured off the Languedocian coast (southern France, northern Mediterranean). The males and females sexually matured between 510–550 mm and 520–610 mm total length (TL), respectively. The largest male and the largest female were 620 mm and 640 mm TL, respectively. There was a significant relationship of total liver mass vs TL between males and females. The diameter of the largest yolky oocytes ranged from 15 to 18 mm (16.5 ± 2.7). Production of egg cases was observed throughout the year, except in September. Egg cases had between 36 and 50 mm (mean: 45.3 mm ± 3.9) in length without horns, and between 14 and 21 mm (18.2 mm ± 1.4) in width. Fecundity remained difficult to assess; an estimation based on production of egg cases enabled us to consider 93 egg cases per year as a maximum.

Seasonal variations in reproductive cycle of Spisula solida were studied between June 1995 and June 1996 at a site off Vilamoura, southern Portugal. Sex ratio was found to be in favour of males. Both males and females showed a synchronism in gonadal development and spawning. Gametogenic activity started with decreasing temperature at the beginning of autumn. The onset of spawning took place in February when the seawater temperature began to increase. Spawning ended in May. It is possible that the white clam does not spawn at a definite temperature, rather responding to the increase in seawater temperature. Between June and September, the specimens were found to be in the resting stage and the condition index increased, probably due to the accumulation of reserves. Spisula solida reached maturity during the first year of life.

Benthosema pterotum is a dominant myctophid in the shelf region of the East China Sea (ECS). They are a key species linking secondary producers and upper trophic levels. We examined the reproductive biology of B. pterotum in the ECS, based on 3065 specimens (10.7–54.8 mm standard length (SL)) sampled during cruises in 1999 and 2004–2009 to enable data over a 12 month cycle to be assessed. Between 14 and 30 mm SL, the ratio of females to males was ~1:1; it increased with SL, and all individuals ≥46 mm SL were females. The gonadosomatic index (GSI) at 50% sexual maturity of females and males was 3.91 and 0.24, respectively. Based on this criterion, females and males can mature at sizes larger than 28 mm and 24 mm SL, respectively. Although mature females having GSI ≥3.91 occurred over nine months (May–January), mean GSI of females peaked sharply during August–September, i.e. the primary spawning period. The hepatosomatic index peaked during April–July, and declined during August–September, indicating storage of materials and energy for reproduction. Based on data from seasonal bottom trawl surveys, small individuals of B. pterotum began to occur abundantly in autumn, and modal body lengths increased progressively during spring–summer, corresponding to the above reproductive seasonality. Oocytes at various sizes were found in mature ovaries, indicating that they are multiple spawners. Egg size at hydration ranged from 0.5 to 0.85 mm. Batch fecundity was positively correlated with SL, and ranged from 253 to 1942 eggs in fish from 30.1–54.8 mm SL.

An updated checklist of manta and devil rays (family Mobulidae) occurring in waters of the Azores archipelago is given based on new data from underwater images and on the re-evaluation of previous citations for the region. There are, at least, three species of mobulids occurring in the region, possibly four: giant manta Manta birostris; Chilean devil ray Mobula tarapacana; and one or both of the giant devil ray Mobula mobular/spinetail devil ray Mobula japanica species complex. These findings have direct implications for the known ranges of all these species and for the conservation of their North Atlantic populations.

The black body-wall pigment of Holothuria forskali shows the characteristics of melanin.

From histological evidence it appears that the pigment is formed in association with the amoebocytes of the coelomic fluid, which eliminate the pigment in the body wall.

The amoebocytes contain a phenolase system, distinct from the cytochromecytochrome oxidase system, with the properties of tyrosinase.

The relation of these findings to those of a preceding and more complete investigation into melanogenesis in Diadema is discussed.

A fishery has developed in recent years in this country for certain hydroids collectively termed ‘white weed’. The hydroids, particularly Sertularia and, more recently, Hydrallmania, are raked up from the sea-bed, processed, dyed and used, largely in the United States of America, for decorative purposes. Fishing for white weed is not new, for it was practised in Germany between the wars. German scientists, notably von Reitzenstein (1913), Pax (1928), and Thiel (1938), examined various aspects of the fishery, and of biology of the hydroids concerned.

The shells of marine invertebrates grow incrementally (Wilbur, 1972). When a section of shell is observed under the microscope, the increments are often visible, separated by fine lines (Fig. 1). Studies of these phenomena have focused chiefly on the periodicity of increment and growth-line formation, principally because of its geological or archaeological application as a ‘biological clock’ (e.g. Wells, 1963; Koike, 1973).

Larvae with three and four chaetigerous segments and also an early post-larval stage of Arenicola marina are described with figures. These are all bottomdwelling stages enclosed in mucous tubes and were collected from the pebble and Fucus zone at Whitstable.

The rinding of these larvae furnishes additional evidence for the view that, except when migrating in the water to new habitats, the lugworm possesses no pelagic larval stage in its life history.

Population growth and concentration factors for 65Zn and 137Cs have been measured for Achnanthes brevipes Agardh, Carteria sp. Diesing, Chlamydomonas sp. Ehrenberg, Dunaliella salina Teod., Nannochloris atotnus Butcher, and Phaeodactylum tricornutum Lewin subjected to factorial combinations of eight temperatures (6–40 °C) and ten salinities (3.5–44.0 p.p.t.). Regression coefficients were calculated for polynomial models describing response surfaces for growth and radionuclide concentration. Salinity was more important than temperature in describing population growth for Carteria, Dunaliella, Nannochloris and Phaeodactylum. No independent variable was consistently of primary importance in describing 137Cs concentration factors, while temperature accounted for more variation in 65Zn concentration factors than salinity or population growth in all algae except Dunaliella. Concentration factors for 65Zn were uniformly higher than 137Cs concentration factors.

MacMunn (1886) extracted a porphyrin from the integument of the starfish Asterias rubens—then known as Uraster rubens—and he considered that this and similar pigments which he had obtained from the slug Arion empiricorum and the coelenterates Flabellum variabile and Fungia symmetrica were identical with the haematoporphyrin of Hoppe-Seyler (1871), which was then the only porphyrin known. Dhéré & Baumeler (1928 a) confirmed the presence of a porphyrin in Arion empiricorum, but did not specify which porphyrin they had found. Kennedy & Vevers (1953), working at the Plymouth Laboratory of the Marine Biological Association, found that the pigment of the integument of Asterias rubens L. was protoporphyrin, and in a further survey of the porphyrins of marine invertebrates (Kennedy & Vevers, 1954), they examined the integuments of two molluscs, Aplysia punctata Cuvier and Duvaucelia plebeia (Johnston), and showed that each contained uroporphyrin I. This pigment was also found by Kennedy & Vevers (1956) to be present in the integument of the tectibranch mollusc Akera bullata (O. F. Müller). The present paper describes the isolation and identification of the po phyrin from the integument of the black garden slug Arion ater (L.). Arion empiricorum was a synonym introduced by Férussac, Férussac & Deshayes (1819–51) to cover the numerous colour and pattern varieties of the slug more generally known as Arion ater. The work appears here since it is a continuation of investigations of mollusc pigments initiated in the Plymouth Laboratory, the results of which have already been published in this Journal.

Benthic macroinvertebrates were sampled seasonally in the subtidal and upper and lower swash zones at two sites in each of six nearshore habitat types on the lower west coast of Australia. The habitat types, which differed mainly in the extent of their exposure to wave activity and whether sea grass and/or nearshore reefs were present, had been distinguished quantitatively using values for a suite of seven statistically-selected enduring environmental characteristics (Valesini et al., 2003). The core samples yielded 121 species representing eight phyla, among which the Polychaeta, Malacostraca and Bivalvia were the most speciose classes, contributing ∼38, 23 and 10%, respectively, to the total number of individuals. The total number of species and mean density of macroinvertebrates at the most protected habitat type (1), i.e. 70 and 209·2 individuals 0·1 m−2, respectively, were far greater than in any other habitat type. Habitat type influenced species composition to a greater extent than either zone or season. Furthermore, the extents of the differences among the species compositions of the six habitat types statistically matched the extents of the differences among the values for the suite of enduring environmental characteristics that distinguished each of those habitat types. Overall, the species composition at habitat type 1 was the most distinct, containing five abundant species of polychaetes that were adapted to deposit-feeding in calm waters with high levels of organic material and which were rare in all other habitat types. In contrast, the fauna at the most exposed habitat type was characterized by four crustacean species and a species of bivalve and polychaete, whose mobility and tough external surface facilitated their survival and feeding in turbulent waters. The zonal differences in faunal compositions among habitat types were greatest in the case of the subtidal zone. The faunal compositions differed among zones and seasons only at the most protected habitat type.

Mytilus edulis absorbs radioactive ‘ soluble’ iron from citrated sea water either directly or via adsorption on to the mucus used in feeding. The adsorption slows or ceases after 3—7 days when the total iron uptake is about I % of the total body content. In order of decreasing radioactivity, iron is absorbed into the byssus threads, renal organ, digestive gland, gut epithelia, gills, walls of heart and blood sinuses and gonadial and muscular tissues.

The occurrence in the summer of 1945 of a swarm of Physalia physalis L. off the south-west coast of the British Isles has initiated a survey into records of its appearance on the Atlantic coasts of Europe during the past 100 years. Unpublished records for 1912, 1913, 1934 and 1935 were discovered and are listed with those already known. The 1945 strandings are considered in detail in conjunction with meteorological data for the period involved. It is concluded that winds, rather than water movements, are the main factor in transporting the swarms towards the British Isles and it is considered likely that the swarms come from the Azores-mid-Atlantic region rather than from the Canaries-Gibraltar district.

Associated with the Physalia were Lepas fascicularis and L. pectinata, some Velella, a few turtles (Caretta caretta), and possibly an Opah fish (Lampris luna), all of them, with some reservation respecting the last-named, surface organisms that would come under the same meteorological influences as the Physalia.

A living specimen of Physalia gave an opportunity to observe the method of feeding of which few previous first-hand accounts exist. The capture of the prey by the dactylozooids and its subsequent digestion by the gastrozooids is illustrated by photographs from life and is described in some detail. It is suggested that the rolling of the pneumatophore from side to side, dipping the crest in the water, is a calm-weather habit directed to keeping moist the upper surface exposed to the air.

The coastal prosobranch Hydrobia ulvae is known to occur in a wide range of marine and brackish habitats and to display great variation in its breeding and life-history characteristics. Several hypotheses have been advanced to account for the latter, including that the variation is environmentally induced and that the species can be divided into ecotypes. Comparison of two adjacent populations in Norfolk, U.K., one from the marine intertidal zone and the other from a non-tidal, landlocked, brackish coastal lagoon, however, disclosed that although shell form differed markedly (including a mean height ratio of 1:1.2), there was no difference in such otherwise variable features as numbers of eggs per capsule, size at hatching and larval type. In both, each capsule contained an average of 21-22 eggs, which hatched at a shell length of 152-154 μn to liberate relatyyively long-lived, free-swimming veligers. The two populations were also interfertile. In no respect had the isolated lagoonal population diverged away from the parent marine one towards the contrasting reproductive strategies characterizing the specifically lagoonal species of Hydrobia that occur nearby. The ‘displacement’ of shell size observed in the lagoon in the absence of sympatric hydrobiids is considered to cast further doubt on competitive character displacement in this genus.

The possibility that marine invertebrates might obtain part of their nutritional requirements by direct absorption of dissolved molecules through the epidermis has recently received considerable attention. This revival of interest in a field which had been virtually abandoned since the early part of the century was led by the findings of Stephens & Schinske (1957, 1958, 1961). Modern analytical techniques have revealed that the amount of dissolved nutrients in coastal waters is much greater than was formerly realized; total amino acids have been recorded in concentrations of up to 10-4 mole/litre in south-east Alaskan waters (Schell, 1974) and 7 x 10-5 mole/litre off Helgoland (Bohling, 1970). Direct absorption of amino acids has been conclusively established in several phyla (see reviews by Stephens, 1968,1972), and one of the major aims of current research is to show that dissolved organic molecules taken up from available concentrations could be of nutritional significance. Recent developments concerning the possible roles of uptake in marine ecosystems have been reviewed by West, de Burgh & Jeal (1977).

Species of marine bivalve molluscs identified in the last nine years in the Greek waters have been used to update the checklist published in 1996 (Fauna Graeciae VII) by inserting necessary changes and adding new records. The updated version includes 13 new species among which three are exotics (non-Mediterranean species), five rare, two new deep sea and one previously considered a fossil species. Also, as a result of new resources, the distributions of pre-existing native molluscs have been updated to include new habitat areas. The nomenclature is also up to date based on the CLEMAM Database. Thus five species are now excluded either because they are junior synonyms of pre-existing valid species (2) or because of old spurious records (3 species). Additions and corrections of the 1996 checklist have resulted in a total of 308 bivalves in Greek waters.