The degree of exposure of a beach to wave action largely determines particle size, sorting and beach gradient (King, 1959) and these, in turn, have a dominant effect on the animal communities within the sand (Swedmark, 1964; Mclntyre, 1969). It is likely, however, that the main turnover of energy, as indicated by the rapid removal of oxygen (Brafield, 1964; Hamilton & Greenfield, 1967), is due to bacteria and algae. On sheltered muddy beaches, motile diatoms can be of considerable importance (Aleem, 1950; Perkins, 1960) but for a relatively exposed beach at Firemore, Loch Ewe, on the west coast of Scotland, Fig. 1, there was negligible unattached plant material, living or dead, and the primary production by the diatoms attached to the sand grains was low (Steele & Baird, 1968). Further, these diatoms did not show evidence of heterotrophy (Munro & Brock, 1968; Mclntyre, Munro & Steele, 1970) yet, at low water mark on this beach, the populations of attached diatoms are relatively uniform to a depth of 20–30 cm in the sand and show no sign of pigment degradation or decreased photosynthetic ability. These conditions at low water mark differ from those at a water depth of 5–10 m where chlorophyll concentration in the upper 5 cm of the sand is higher but where pigment degradation and blackening of the sand, indicating reducing conditions, are usually found below 10 cm depth of sand.

The Plymouth Marine Fauna (Marine Biological Association, 1957) list of monogenean parasites of fishes has been increased from 39 to 58 species and in addition 2 species have been recorded from a cephalopod host. The increase in listed species represents an increased ‘parasitological effort’ rather than an influx of new species into Plymouth waters.

Eulalia viridis is the most common littoral phyllodocid at Cullercoats Bay, where it occupies crevices and small holes in the well-sutured sandstone and limestone rocks. It is particularly common in rocks having a heavy encrustation of barnacles. The reproductive biology of this species in particular, and of phyllodocids in general, is poorly known. Meyer (1938) has described the development of larvae of Eulalia viridis both from artificial fertilizations and from egg cocoons said to belong to Eulalia viridis collected in January at Plymouth, U.K. The observations made during the present investigation differ in a number of important respects from those of Meyer and his conclusions cannot be considered appropriate to all populations of E. viridis.

1. It has been shown that the stomach of the plaice can digest proteins by an extra-cellular enzyme—apparently pepsin. Fats and carbohydrates appear to be unattacked in the stomach.

2. In the intestine, proteins are further attacked and the mucous membrane contains a trypsin and an erepsin.

3. The liver and the wall of the gall-bladder are more potent sources of trypsin than is the intestine; the former contains, also, a cathepsin, and the latter an erepsin. It is not certain whether any of these enzymes can be secreted into the intestine; administration of pilocarpine failed to make the bile definitely active in digesting proteins, but it is possible that there may be some other route by which the secretion may reach the intestine.

4. Fats and carbohydrates are digested in the intestine, since the mucous membrane of the intestine—and also the wall of the gall-bladder and the liver—contain lipase and amylase. The liver is a far more potent source of lipase than is either the gall-bladder or the intestine, but this lipase may be partly intra-cellular in action.

5. The hydrogen-ion concentration of the contents of the stomach and intestine has been shown to be consistent with the extra-cellular action of the enzymes found in the respective mucous membranes. The mucous membrane of the stomach is capable of secreting acid, and that of the intestine is capable of bringing about its neutralisation.

Anatomical and histological details are here given of two organ systems, which, my experiments lead me to believe, may secrete hormones concerned in the sex reversal that overtakes all male Pandalus borealis Kroyer. The descriptions eschew any attempt at detailed cytology, and refer exclusively to prawns taken from the population of Gullmarf jord in south-west Sweden. There is reason to believe that, as with Palaemon (= Leander) serratus (cf. Carlisle, 1955), different populations may vary widely in the detailed topography of the endocrine organs, as well as in appearance, life history and growth rate (cf. Horsted & Smidt, 1956).

INTRODUCTION

This analysis of cephalopod remains, particularly the mandibles or beaks, from sperm whales caught off Iceland is one of a series made by the authors on remains from various geographical regions including Madeira (Clarke, 1962a), Spain (Clarke & MacLeod, 1974), Western South America (Clarke, MacLeod & Paliza, 1976, South Africa, Western Australia, the Antarctic and the South Atlantic (Clarke, 1976, 1977). Other workers have described similar collections from New Zealand (Gaskell & Cawthorne, 1967; see also Clarke, 1976, 1977) and the North Pacific (Akimushkin, 1954; Betesheva & Akimushkin, 1955; Tarasevich, 1963). The present analysis has depended upon a development in the technique of identification of cephalopod lower beaks from an early search for criteria (Clarke, 19626) to a point where many species can be identified from lower beaks (Mangold & Fioroni, 1966; Iversen & Pinkas, 1971; Clarke, 1977).

INTRODUCTION

In the genus Laminaria the origin of the growth of the frond (blade, lamina) is known to be the meristematic transition zone between frond and stipe. Parke (1948) showed, by observing holes punched in the frond, that the fastest rate of growth in length in L. saccharina (L.) Lamour. was in the proximal 25 mm. However, during measurements of the rate of growth of fronds of plants of known age on previously cleared areas (Kain, 1976), it was noted that in L. hyperborea (Gunn.) Fosl. the maximum rate of elongation occurred at some distance from the transition zone. This led to an investigation of the whole pattern of growth, in terms of elongation, increase in area, decrease in thickness and change in cell size and numbers over the surface of the frond at different stages.

Studies of recruitment dynamics in meroplanktonic organisms are dependent on the correct identification of each ontogenic stage of each species. This is particularly difficult when studying the larval stages, which are not easy to identify due to their lack of resemblance to conspecific adults and their high degree of similarity with congenerics at the same stage of development. This is the case with the crustacean megalopae of the genus Cancer along the coast of the south-eastern Pacific. This fact represents a serious limitation on ecological studies of populations of these species which constitute a heavily exploited local resource. In this study we describe in detail field collected megalopae larvae of three sympatric crab species of the genus Cancer(C. edwardsii, C. setosus and C. coronatus). As a result of this analysis we were able to identify easily visible diagnostic characters which allow the species to be distinguished from one another. The megalopae were easily distinguished by the form of the cheliped and the presence of spines on these. Cancer edwardsii has an elongated globulose cheliped, whereas C. coronatus has a subquadrate one. Both species possess a prominent ischial spine, which is absent in C. setosus. We corroborated the utility of these diagnostic characters by comparing the COI gene sequences of mitochondrial DNA of larvae identified by morphology with sequences taken from samples of the adults of all species of Cancer found in the region. We discuss the morphological variations between larvae found across the region (i.e. at sites separated by more than 800 km) and between megalopae obtained from the field versus those cultivated in the laboratory. We conclude that the simultaneous use of morphological and molecular tools for identification of decapod larvae appears useful for the study of cryptic species.

This study examined the association pattern of two snapping shrimp species that inhabit burrows at exposed rocky shores of the Chilean Pacific coast. The two species Alpheus inca and Alpheopsis chilensis were frequently found to share the same burrows. In most burrows an heterosexual pair of each species was found. A strong positive correlation between the body length of female and male conspecifics cohabiting in a burrow was found both for Alpheus inca and for Alpheopsis chilensis. Similarly, a positive correlation existed between the mean body length of Alpheus inca and that of Alpheopsis chilensis occurring together in one burrow. Thus, a size-relationship between burrow cohabitants exists both in the intra-specific as well as in the inter-specific association of these shrimps. Most females, regardless of their reproductive stage, were accompanied by males. Within a particular burrow, females of the two species often were in the same reproductive stage, i.e. both were with embryos in a similar developmental stage, or both were without embryos. These data suggest that male and female conspecifics, as well as the pairs of the two species, remain together in the same burrow for relatively long time periods. It is proposed that the intra-specific communication system of snapping shrimp facilitates the development of inter-specific associations, such as the one reported herein.

Macroalgal communities of coastal ecosystems play a key role in maintaining overall coastal biodiversity. In this study, habitat preference (macroalgal host preference) and temporal changes (season) of epifaunal communities associated to five macroalgal species such as Padina, Sargassum, Ulva, Acanthophora and Gracilaria were observed at seasonal intervals (summer and winter) for 2 years from May 2012 to March 2014 on the Jeddah coastal waters of the Red Sea. Major epifaunal groups observed included polychaetes, amphipods, isopods, gastropods, mussels and crabs. Polychaetes were represented by 10 species followed by amphipods with five species. The abundance of gastropods, polychaetes and mussels showed significant variation between the macroalgae irrespective of morphology. Generally, the abundance of these taxa were high on Padina and low on Sargassum. Significant seasonal changes were observed on the abundance of polychaetes, amphipods and isopods. The abundance of some epifaunal groups showed a significant relationship with environmental parameters such as surface water temperature, salinity, pH and dissolved oxygen content.

Relatively little is known about spatial turnover of marine benthic taxa in the diverse reef environments of Indonesia and how this is structured by environmental conditions. In the present study the community similarity of sponges was related to environmental and spatial variables. In total, 150 sponge species (N=15,842) were sampled within the Spermonde Archipelago in the Makassar Strait, off south-west Sulawesi. Ordination revealed that sponges are primarily structured by a complex interaction between depth, exposure and on-to-offshore variation in environmental variables. Together, environmental and spatial variables explained 56.9% of the variation in similarity of which 10.9% was due to environmental variables alone, 2.6% due to spatial variables alone and 43.4% due to covariation of environmental and spatial variables. The large amount of variation explained by the spatially structured environmental component is due to a strong on-to-offshore gradient in a number of environmental variables including temperature, velocity, salinity and suspended sediment load. Ordination was also used to identify associations between species and environmental variables.

This paper is a first detailed contribution to the knowledge of serpulid diversity from marine caves of the eastern Mediterranean Sea. A total of 27 taxa were recorded in two submerged caves of Lesvos Island, in the Aegean Sea. A clear trend of variability was observed with serpulid abundance, specifically that of sciaphilic and deep-sea species, increasing inwards while the number of taxa and species diversity did not change significantly across the two caves. In the innermost sectors of the studied caves two types of bioconstructions were observed: (a) ‘coiled doughnuts’ of Protula, recorded for the first time in Mediterranean caves; and (b) ‘biostalactites’ mainly consisting of skeletal metazoans recorded for the first time from the eastern Mediterranean. The results of the present study revealed new faunal elements and type of bioconstructions for the Mediterranean marine caves, showing that several aspects of their communities are still poorly known and deserve to be further investigated.

Diel variations in the emergence of the burrowing prawn Nephrops norvegicus (L.) have been investigated by direct field observations (Chapman & Rice, 1971; Chapman, Johnstone & Rice, 1975; Chapman & Howard, 1979; Atkinson & Naylor, 1976), and indirectly by sequential trawling during 24 h periods (Höglund & Dybern, 1965; Simpson, 1965; Hillis, 1971; Farmer, 1974; Atkinson & Naylor, 1976; Oakley, 1979). Peak emergence appears to be related to temporal and depth-dependent variations in daylight penetration, since Nephrops are apparently nocturnal in shallow waters, crepuscular as the depth increases, and diurnal at the greatest depths of their occurrence. This lends support to the suggestion that emergence occurs at an optimum light intensity (Hillis, 1971; Chapman, Priestley & Robertson, 1972; Chapman, et al., 1975; Chapman & Howard, 1979). However, additional factors influencing emergence of Nephrops from their burrows have also to be taken in account, since laboratory studies of locomotor activity in Nephrops have consistently revealed nocturnal activity patterns in light-dark (LD) regimes, with light inhibiting locomotor activity even at extremely low irradiance levels (Arechiga & Atkinson, 1975; Atkinson & Naylor, 1973, 1976; Naylor & Atkinson, 1976). Moreover, Hammond & Naylor (1977 a) have presented qualitative evidence that the nocturnal locomotor activity peak appears to be synchronized by falling light intensity at dusk. The differences between these experimental results and emergence patterns deduced from trawl catches and underwater observations of Nephrops have not been fully resolved by studies of the role of light intensity and of gradual light transitions (Arechiga & Atkinson, 1975; Hammond & Naylor, 1977 a, b). Thus the behavioural responses of Nephrops both in the field and in the laboratory need to be assessed in relation to more accurately quantified light changes. Also, despite earlier evaluation of the problem (Atkinson & Naylor, 1976; Hammond & Naylor, 1977a) it is necessary to reconsider the possibility that the patterns of locomotor activity recorded in the laboratory are influenced by experimental conditions, as has been demonstrated for minnows (Jones, 1956), and flatfish (Verheijen & de Groot, 1967).

The locomotor performance of the Mediterranean sea urchin Paracentrotus lividus was investigated under laboratory conditions. Individuals were placed singly in the centre of a glass surface positioned either horizontally or vertically in tanks with seawater, and their locomotor activity was recorded. For locomotion on a horizontal surface, speed increased with both sea urchin diameter and their straightness of path. Speeds on a vertical surface were size-independent and not related to the straightness of path, although they were affected by vertical path orientation, with the highest speeds occurring for downward movements and the slowest speeds for the upward movements. Taken together, these results suggest that the scaling of sea urchin locomotion may follow similar laws to those of legged animals, for which locomotor performance increases with size on horizontal surface, while their relative cost of locomotion increases with body size on inclined surfaces. It is suggested that differences in horizontal vs vertical locomotion may also be related to differences in the underlying locomotor mechanisms, i.e. using adhesive appendices (tube feet) or levers (spines). In a second experiment, the sea urchin speed obtained during a negative phototactic response to a direct light stimulus was recorded. The results show that speed during light stimulation is higher than that during spontaneous locomotion in sea urchins of intermediate size (2·5–4 cm), suggesting that, in addition to the direction of locomotion as shown by previous studies, light can also have an effect on speed.

Data on age and reproduction of the rabbitfish at the Portuguese continental slope are presented. Ages were estimated based on transverse sections of the dorsal spine. Differences in growth patterns were detected between sexes—males grow slower and are smaller than females. The results from histological analysis of different development stages of testes indicated that the macroscopic scale used is well adapted to rabbitfish sampled in Portuguese waters. In females and excluding macroscopic Stage 4, which according to the adopted scale corresponds to an active phase, all the remaining stages were identified in the samples. Ovarian fecundity was estimated as 6·46±2·32 oocytes (females range: 45·0 to 70·0 cm pre-supra caudal fin length [PSCFL]). Length of first maturity in males (40·7 cm PSCFL) is lower than in females (45·9 cm PSCFL).

Field and laboratory observations were made of the erycinacean bivalves Montacuta substriata and M. ferruginosa, which are usually considered as ‘commensals’, respectively, with the burrowing spatangoids Spatangus purpureus and Echinocardium cordatum. These species were obtained mainly from the Plymouth area, where M. substriata was also found with E. flavescens and E. pennatifidum, and also very occasionally with E. cordatum. Similarly, M. ferruginosa was also found with 5. purpureus, E. flavescens and E. pennatifidum. This indicated that the associations are not as specific as had been thought.

The variation in the fecundity of a fish species from year to year has not received much attention, although the changes in the numbers of young fish in the plankton are well documented for the Plymouth area (Russell 1930–47; Corbin, 1948–51). The most important work considering fecundity fluctuations is that of Simpson (1951) who, working onPlaice, Pleuronectes platessa L., concluded that during 1947,1948 and 1949 there was a steady decrease in the number of eggs laid, this being due to a decrease in the mean size of the spawning fish which he showed to be correlated with the egg numbers. Simpson's interest in the fecundity was to provide a more accurate estimate for determining the number of plaice in the total population from planktonic egg surveys similar to the work of Buchanan-Wollaston (1923). He did not consider in detail whether the fecundity for a given length might change from year to year. It is this problem which will be considered here. Estimates of fecundity of Long Rough Dabs, Hippoglossoides platessoides (Fabr.), will be analysed, and Simpson's Plaice data will also be considered.

Production rates and production/biomass ratios have been estimated for a large number of macrobenthic species (Hargrave, 1977; Robertson, 1979). The usefulness of such estimates is limited by a lack of information on their temporal and spatial stability; we are aware of only one study (Sarvala, 1980) in which production has been estimated for more than one year. The present study investigates the stability of the production (P), biomass (B) and P/B values of two polychaete species, Nephtys hombergi Savigny and Ampharete acutifrons (Grube), over a 5-year period.

A sea anemone, normally a passive-looking animal, reacts to suitable food-stuffs by a series of fairly complicated activities. When its tentacles encounter solid food there is, first of all, a discharge of cnidae, which poison living prey and adhere to the food mass. These cnidae are independent effectors, responding directly to external excitation (Pantin, 1942). Next, the tentacles clasp the food and bend towards the mouth; they push the food into the mouth, and the pharynx draws it down into the coelenteric cavity where it is digested (Pantin & Pantin, 1943).

Gastropod shells are essential to most hermit crabs. Shell availability limits hermit crab populations. Shells provide protection and the degree of shell-fit controls crab growth and fecundity. Crabs locate new gastropod shells from a distance under water by molecules released from gastropod flesh during predation events. Here we test the hypothesis that the salivary glands of the predatory gastropod are the source of enzymes that digest muscle proteins and release peptide attractants. We describe the anatomy of both the acinous salivary glands and the tubular accessory salivary glands of Busycon contrarium which are similar to those of B. carica. The salivary gland ducts empty at the mouth, suggesting a role in the primary digestion of food. We show that gastropod muscle proteins, extracted by salt solutions with the ionic strength of sea water and purified by precipitation in low ionic strength can be digested by gastropod salivary gland enzymes to generate peptides attractive to the hermit crab, Clibanarius vittatus, in field assays.