Schistomysis spiritus (Norman) breeds throughout the year in the Clyde and in Loch Ewe, Wester Ross, but breeding is more intense at some seasons than others. The over-wintering population in the Clyde breeds in March/April, the progeny growing and becoming sexually mature in July/August to produce a further generation which matures and breeds in October/November. In Loch Ewe the over-wintering population breeds in February, March and April and members of this spring generation begin breeding in May and continue to breed until September; the number of S. spiritus breeding in Loch Ewe decreases sharply after September and no autumnal peak of breeding, such as that in the Clyde, was found during the period investigated. The number of young carried in the marsupium varies seasonally, being 20–30 in May/June and 2–6 in midwinter. The food and the horizontal and vertical diurnal and seasonal movements of this species are discussed.

The amino-acid composition of Balanus balanoides (L.) and B. balanus (L.) da Costa eggs during their development has been investigated. Protein accounts for 70–80% of the dry matter. The amino-acid composition of the eggs is similar to that reported for Calanus finmarchicus, for which reliable information is available. Loss of all amino acids takes place during development, but the relative amounts of glycine and alanine increase in the late stages. The rates of loss are far greater in B. balanus, where the eggs themselves develop more rapidly. In B. balanoides there is a distinct ‘ arrest’ in the rate of loss of amino acids at the H-stage; this is coincident with a similar arrest in the loss of other metabolites and in development. Loss of nitrogen from the eggs has been measured directly and the results compared with the values calculated from the analyses. In the early stages the agreement is good if allowance is made for the difference in temperature between the elution experiments and the natural environment.

Data have already been presented (Barnes, 1965; Dawson & Barnes, 1966) on the major biochemical constituents of the eggs of two common cirripedes, Balanus balanoides and B. balanus, and on changes in these constituents during development. It has been shown that protein nitrogen is lost throughout development and that the rate of this loss is greatest during the early stages; also that nitrogen utilization relative to that of carbohydrate is greater in B. balanus. The more rapid development of the eggs of the latter species gives rise to a greater rate at which all substrates are utilized, but the proportions disappearing—relative to the initial quantities—are not widely different; rather more is lost in the species that develops more rapidly.

Anchor-dredge samples of the benthos in Weymouth Bay and Poole Bay were taken after the severe 1962–63 winter to ascertain what changes in the fauna had occurred. The same station positions as had been previously sampled in 1958 and 1959 were re-sampled in 1963–64 and the results from each Bay compared.

Most species had survived the previous winter, when sea temperatures had probably been at 3° or below for about a month, but populations of the bivalve molluscs Venus verrucosa and Venerupis rhomboides, previously common in the area, had suffered severe mortalities, none being taken in the 1963–64 samples. The brittle star Acrocnida brachiata had also disappeared from the samples, and many other invertebrates appeared to have declined in numbers. Two cold-water species, Spisula elliptica and Buccinum undatum, showed if anything a slight increase, perhaps reflecting colder sea temperatures over the past few years. Crepidula fornicata also showed an increase in numbers.

Mortalities were not necessarily of species close to the limits of their range, some of the latter having survived with no noticeable decline in numbers.

Studies of a natural population of N. virens Sars at Southend reveal that the oocytes take a little over a year to mature. After a period of relative quiescence they grow rapidly between September and December and then increase little in size until early May. Within a given specimen small oocytes are more variable in size than large ones. Sperm develop fully from coelomic sperm plates in about eight months, and are mature by the beginning of May. There is a period during which they are characteristically clumped in quartets.

Spirula spirula (L.) when freshly caught was found to be close to neutral buoyancy. The pressure of gas within the chambers of the shell was always less than atmospheric, being very low in the newest chamber of a growing animal and rising to a value a little below atmospheric in the older chambers. A chamber which was being formed was completely full of liquid. The only connexion between the liquid in a chamber and the living siphuncle is through a small permeable region of the siphuncular wall which lies at the top of a newly formed chamber. These results support the hypothesis that Spirula, Nautilus and Sepia all regulate their buoyancy in the same way. The shell is sufficiently strong to withstand the hydrostatic pressure of the sea at the depths at which the animal lives.

The work of Colebrook & Robinson (1965) has shown that there are three groups of seasonal cycle in production in the north-east Atlantic. There are three ‘races’ of herring in the same area, spawning in autumn, winter and spring. Taking the dates of spawning of each ‘race’ and the date by which the larvae must have food, a connexion can be made between the herring race and the production cycle in the area in which it lives. It is assumed that the date of spawning is fixed and does not vary with environmental conditions. Once the connexion between herring race and production cycle is made, certain comparisons can be made between races in growth rate, reproductive capacity and in the variability of recruitment. It was tentatively concluded that the magnitude of the year-class in the three north-east Atlantic races must be determined before metamorphosis. After metamorphosis, herring live on the beaches where the production cycle must have quite a different character.

Introduction

Herring populations have been grouped as spring and autumn spawners ever since they have been examined scientifically. Autumn spawners have been further subdivided into early autumn (or summer) and late autumn (or winter) spawners (Johansen 1924). Since the discovery of sharp differences in fecundity and egg size between early and late autumn spav/ners (Polder & Zijlstra, 1959), the distinction between them has acquired the same status as that between autumn spawners and spring spawners. However, there are very marked differences between all three groups, and to relate them to then-calendar times of spawning it is proposed to name then ‘ autumn’ (formerly early autumn), ‘winter’ (formerly late autumn) and ‘spring’ spawners.

Nomograms are presented for solving the equations relating the concentrations of chlorophylls a, b and c to sample volume and the extinctions of acetone extracts at three wave-lengths.

In experiments in Cornwall and Yorkshire 214 marked lobsters (Homarus vulgaris M. Edw.) were returned after moulting. Of these a number had moulted more than once, and the separation into once-, twice- and three-times-moulted lobsters was achieved using probability paper.

There was no significant difference in growth of lobsters from the two areas. It is concluded that the best method of plotting growth in lobsters is to plot carapace length before moulting against carapace length after moulting.

It is concluded that male lobsters show arithmetic growth over the size range 68–123 mm carapace length, adding a constant mean increment of 9.8 mm carapace length at each moult.

It is concluded that arithmetic growth, with a mean increment of 8.4 mm, adequately describes the growth of female lobsters over a small size range centred on a mean size of about 85 mm, but would lead to inaccuracies over a wider size range.

The concept of arithmetic growth in relation to the general growth pattern is briefly discussed.

Introduction

In a population study a knowledge of the growth rate is essential. In crustaceans estimation of the growth rate is complicated by two factors: first, it is usually not possible to age the animals, and second, the growth rate is made up of two components, the increase in size at moulting and the frequency with which moults occur.

The present paper presents data on the growth of lobsters at a moult, obtained from field experiments conducted in Cornwall in 1957–59, and in Yorkshire in 1958 and 1960.

The inability of Lima Mans Gmelin to enclose the soft tissues of the body within the shell is correlated with the development of other defensive adaptations.

L, Mans can automize entire pallial tentacles or parts of tentacles which subsequently secrete a viscous mucus distasteful to potential predators. Autotomy takes place at transverse septa along the length of the tentacles and mucus is secreted by epidermal gland cells.

The transverse septa of the tentacles also regulate the hydrostatic pressure of blood within the tentacles and permit the performance of complex locomotory movements. It is suggested that the septa were originally developed to serve this locomotory function and, secondarily, function as planes of weakness at which autotomy may take place.

L. Mans builds protective nests. The nests are constructed by burrowing into a gravel substratum and consolidating the walls of the burrow with byssal threads. When disturbed in the nest L. Mans performs locomotory movements which lead to enlargement of the nest. If the nest is broken the locomotory activities result in free swimming followed by attempts to burrow into the substratum to form a new nest. It is unlikely that L. Mans swims freely in nature except when displaced from the nest.

Introduction

Most bivalve molluscs react to unfavourable stimuli by retracting the soft parts of the body within the shell valves and contracting the adductor muscles to oppose the valve margins. In Lima hians Gmelin the mantle margin, even with its numerous long tentacles fully retracted, cannot be accommodated within the shell valves. In this paper the inability of L. hians to retract the soft parts within the valves is correlated with two types of defensive behaviour: (i) the secretion of mucus by the tentacles of the mantle margin and the autotomy of these tentacles, and (ii) the interrelated activities of swimming and nest-building.

Several aspects of polymorphism in Hydractinia echinata (Fleming) have been examined. Polymorphism in Hydractinia appears to be the result of inhibition of the normal developmental sequence and not the result of direct genetic control. The inhibition is mediated by both intrinsic and extrinsic factors. The former are responsible for the formation of reproductive zooids in the colony, but this process may be accelerated by extrinsic factors (crowding, increased pCO2). It is suggested that intrinsic factors consist of an inducer or growth stimulator produced in the hypostomal region of the polyps and an inhibitor of growth and differentiation produced by dividing cells beneath the hypostome. The ratio of these two factors throughout the colony ultimately determines the polyp type which will be formed.

In the coxal region of Palinurus vulgaris Latr. the following proprioceptors are present: (1) a thoracico-coxal muscular receptor, (2) two innervated elastic strands (depressor and levator receptors), and (3) a coxo-basipodite receptor. Thus, Palinurus has the same number of these organs as some Brachyura and Anomura, but differs from Homarus and Astacus, which have five of them.

In all the five thoracic segments carrying the legs the receptor organs in Palinurus originate on special receptor rods which are thin projections of the endophragmal skeleton.

The muscle elements of the muscular receptor are surrounded by connective tissue which in the proximal part of the muscle forms a thick sheath. To the receptor rod the muscle is attached by a short tendon. The motor fibres reach the receptor muscle at about the midpoint of its course.

Tissues from a number of marine species were treated with a variety of solutions, including 1% of the major ‘detergent’ (B.P. 1002) used in attempting to disperse the oil from the ‘Torrey Canyon’ and 1% of each of the three major constituents of B.P. 1002, two of which are non-ionic surfactants.

The extracts were submitted to vertical starch-gel electrophoresis in order to measure both the effect of the detergent in facilitating the breakdown of cellular structure (extractability), and the irreversible effect on activation or inhibition of various enzymes and other proteins.

The proteins studied include a variety of NAD- and NADP-linked dehydrogenases, esterases, blood and nerve haemoglobins, plasma proteins, egg white and yolk proteins, and r-phycoerythrin.

The results confirm the general opinion that detergents increase the extractability of proteins from cells. In particular lipoprotein systems are altered, e.g. ‘fast’ serum lipoprotein in fishes (and other vertebrates). Other effects are also observed, e.g. sole but not turbot haemoglobin is rendered relatively insoluble, probably because the detergent stabilizes haemoglobin binding to other components in the erythrocyte. Certain enzymes, e.g. some esterases and amylases, are activated—a not surprising observation. However, a few enzymes are altered in electrophoretic mobility or in activity in a way that one might not expect, e.g. bass Morone labrax lactate dehydrogenase.

The results indicate that ‘oil-spill’ detergents and their constituent surfactants are biochemically quite powerful agents. It is too early to attempt to correlate in vitro and in vivo observations but there is an indication that starch-gel electrophoresis provides a useful supplement to more conventional methods used in the studies on complex pollution problems.

A description is given of a filamentous red alga which was found growing within a sponge collected from the sublittoral off Santander, Spain. The plant appears to be closely related to Acrochaetium spiculiphilum Dawson. A survey is given of the specific characters available for the typification of the known partially and completely endozoic Acrochaetium species, and some suggestions made on the more important lines of study.

Introduction

During the summer of 1957 some specimens of the keratinous sponge Haliclona were collected from the sublittoral off Santander, Spain, by Mr G. R. Forster. Certain of the specimens bore extensive areas of red, and on preliminary examination this colour was found to be due to the filaments of a red alga showing an extensive ramifying growth within the skeleton of the sponge. The drawings and cell measurements to be reported were made from the plant material by A. D. B. soon after its collection. This information has been retained pending a more comprehensive study of endophytic and endozoic red algae. Work is now in progress on these lines (mainly by E. B. W.), and a re-examination of the Santander material has enabled us to make a critical study of the data available for a precise typification of plants of this habit. Further, since the association of endozoic filamentous red algae with sponges appears to be of rare occurrence, any examples need to be fully described.

Description of Plant

The cells were of variable shape and size, and contained much-dissected parietal chromatophores (Fig. 1 a). Individual filaments tended to be closely packed together within the host (Fig. 1 b), and there was no extensive growth of erect filaments outside of the host material.

Diving observations and more wide-spread coverage by Asdic show that the late Holocene basal neritic deposits of the broad bay between The Lizard and Start Point are represented by three main facies whose character depends on the two bed-transport paths converging there. The sheet sands laid at the end of the path with a good supply show a progressive geographical change in texture. On the other path, where sand is in short supply, there are elongated patches of somewhat coarser, well-sorted sand with ‘silt’ balls, alternating with shell-rich gravel patches. While the sand patches are laid out along the path of the strongest tidal currents, the ripple marks of the gravel can only be constructed by long waves from the Atlantic.

Ectocarpus distortus and E. landsburgii are shown to be conspecific and to constitute free-living ecads of E. fasciculatus. It is therefore recommended that the two should no longer be regarded as true species although it is pointed out that the specific epithet E. distortus may have priority over E. fasciculatus. If so, the entire complex, provisionally retained as E. fasciculatus, may have to be known as E. distortus. Meanwhile it is recommended that the list of British Ectocarpus spp. be reduced to two, namely E. fasciculatus and E. siliculosus.

The eye of the larval herring has only single cones in the retina. They are characteristic in ultrastructure at this stage with a striated outer segment, an ellipsoid packed with mitochondria and with a connecting cilium at the junction. Cones are gradually added at the margin of the retina as the larva grows. There are no retinomotor responses in the larval eye. It has, however, adult characteristics in the postero-ventral area temporalis (though it is undifferentiated at this stage) with its blindly ending anterior pocket and in the falciform process closing off a trough-shaped ‘ancillary’ eye.

At metamorphosis (30–40 mm) a number of changes occur: the area differentiates, twin cones and the rods appear, the latter perhaps developing from cells originating in the bipolar layer and migrating to a position inside the external limiting membrane. Retinomotor pigment migration and change in length of the cone myoids also develop when the eye is subjected to changing light intensities, the threshold being 1.0–0.01 me (metre candles).

In the adult eye the fully developed retina has an area temporalis packed with single cones giving high acuity on the main visual axis, which is in the upperfore direction. The lens presumably gives accommodation by postero-ventral movement brought about by a postero-dorsal suspensory ‘ligament’ and a ventroanterior falciform process. This process also delimits the area and divides off the ‘ancillary’ eye from the main retina.

Over the whole range of development the cone ellipsoids grow in diameter from 2 to 12 μ and decrease in density correspondingly.

The algal symbiont of Convoluta roscoffensis (Graff) has been studied with the light and electron microscopes both in situ in worms collected from four localities on the coast of Brittany and in various forms of isolates in culture. The same organism has also been obtained from populations of free-living monads collected from sand and water samples adjacent to the Convoluta colonies. Its structure and behaviour in culture are described and illustrated. Platymonas convolutae sp.nov. is a very distinct species with a rough-surfaced theca and a pyrenoid with some new characters not previously recorded in other members of the group. Some new information on scale and theca production from the Golgi system has also been obtained.

The histology of the spurdog (Squalus acanthias L.) testis was observed through a complete annual cycle. The maximum sperm accumulation coincided with the breeding time as defined by the biennial female cycle. Degeneration of spermatogonia was observed following breeding. The band of degenerate germinal ampullae was identical to that described as occurring in Scyliorhinus canicula (L.) following pituitary ventral lobectomy. This suggested a resting phase in the production of a specific pituitary gonadotrophin lasting for about four months. All spermatocytes were transformed to spermatozoa within 12 months. 3β-Hydroxysteroid dehydrogenase activity was located in semen, in Sertoli cell cytoplasm and in the lumens of mature germinal ampullae. A possible seasonal change in this activity due to the migration of the degenerate band is suggested. Interstitial cells of Leydig could not be observed.

INTRODUCTION

The Scottish-Norwegian stock of the spurdog, Squalus acanthias L., sampled for this study, was shown by Holden (1965) to make an autumn breeding migration from the region of the Orkney and Shetland isles to the breeding areas in the Minch off north-west Scotland. During January and February those females carrying embryos at the end of their second year of development move inshore and liberate their young in shallow water. At this time the ovaries of these fish contain from three to fifteen eggs ready for ovulation (Holden & Meadows, 1964), and observations suggest that copulation, ovulation and the commencement of a further pregnancy follow almost immediately. Following copulation, the spermatozoa must reach the oviducal gland at the head of the oviduct in order that the eggs may be fertilized before they are enclosed by the candle membranes.