Three deep-water species of the north-eastern Atlantic have been studied: Caryophyllia abyssorum Duncan, 1873, C. calveri Duncan, 1873, C. sarsiae n.sp. Of these only C. abyssorum has not been found in the Mediterranean. In the north-eastern Atlantic these species appear characteristic of somewhat different depths, but occasionally can be found together. Obtained by early deep-sea expeditions (“Porcupine” cruise of 1870, cruises of Prince Albert I of Monaco), all three species have been previously confused and assigned, chiefly, to the little-known fossil species C. arcuata and C. cylindracea. In order to show the world-wide confusion about C. arcuata, some other records, from Cape Verde Islands to Japan through Antarctica, are quoted.

The changes in the number of species, the number of individuals and the production of a benthic mud association have been studied for a 4-year period. The numbers of species and the total estimated production appear to have remained substantially stable, but the number of individuals has more than doubled over the period. When considering the high ranking producers, it is clear that not all of these have contributed to the general rise in numbers of individuals. Two species, Ammotrypane aulogaster and Abra nitida have shown an abrupt fall in population numbers and biomass. At the beginning of the investigation in 1971, these species figured importantly in the production estimates with 20 and 6% respectively of the total production. After 1971, both were effectively eliminated from the production of the association.

Young Homarus vulgaris were reared in the laboratory up to stage V. All settled during stage IV by burrowing under stones placed on a sand or mud substrate. Half of the 100 animals studied burrowed within 6 days of reaching stage IV and did not subsequently vacate the burrow. The burrows were made with two openings on opposite sides of the stone which, in the case of the sand burrows, served as a roof. The burrows were made by the same methods as previously described for young and adult H. americanus

Moult increments, annual moult frequency and hence annual growth were determined from suture-tagged edible crabs (Cancer pagurus L.) released and recaptured off Devon, Cornwall, and Dorset.

The average moult increments of males and females at a premoult carapace width of 100 mm were similar; at larger sizes the average moult increment of females was considerably less than that of males. Annual moult frequency of C. pagurus in south-west England decreased with increase in size, females more so than males.

As a result of the smaller moult increments and lower moult frequency of females, their annual growth is considerably less than that of males. This appears to be the result of three aspects of sex and reproduction: (1) reduction in moult increments, probably as a result of competition for nutritive resources between egg production and body growth; (2) the interruption of the moulting cycle by successive annual spawnings from a single impregnation at the previous moult; and (3) accentuation of the larger increments in weight at moulting of male crabs due to the allometric growth of their chelae. A consequence of the higher growth rate of males is the presence of very large male crabs – a distinctive feature of the population structure of the stock off south-west England.

The growth of C. pagurus in south-west England was compared with published data for stocks off the east and north-east coast. Moult increments were similar for both areas, but there were considerable differences in the moult frequencies. In the south-west, males moult more frequently than females; the opposite is the case for the east and north-east crab stocks. A valid reason for this difference has not yet been established.

Chemostats were used to study the relation between growth rate, the rate of nutrient uptake and internal and external nutrient concentrations of two nutrients simultaneously. (Monochrysis lutheri: phosphorus and vitamin B12.)

Growth rate and internal concentrations of both limiting and excess nutrients are related by simple rectangular hyperbolas.

Control was shown to follow a threshold rather than multiplicative pattern; that is, non-limiting nutrients exert no control at all over the pattern of growth. The limiting nutrient was the one that showed the smallest cell quota: subsistence quota ratio.

Monochrysis populations exhibited two modes of growth. ‘Slow adapted cells’ differed from ‘fast adapted cells’ in the values of the constants for the above relation.

Uptake of both limiting and non-limiting nutrients was found to be controlled by internal as well as external substrate concentrations. There was thus a limit to luxury consumption of one nutrient when growth was limited by another.

The mathematical model formulated for growth in a chemostat (equations (23)–(29)) allowed prediction of external and internal substrate concentrations and rates of uptake of two nutrients and of biomass, given only the input concentrations of the two nutrients and the dilution rate. This model should apply equally well to growth in batch cultures; its possible application to natural populations was discussed.

A bloom of the dinoflagellate Gyrodinium aureolum Hulburt in the eastern Irish Sea during September and October 1971 was accompanied by unusual mortalities of Arenicola marina L. and Echinocardium cordatunt Pennant. Observations in the field and laboratory suggest that the mortalities may not have been directly related to the occurrence of Gyrodinium but could have been a consequence of unusual climatic conditions which resulted in oxygen depletion in benthic substrates. The decomposition of the bloom possibly aggravated the situation.

Specimens of Golfingia margaritacea (Sars) (Sipuncula) from the south coast of Devon and Cornwall and from Raasay, West Scotland, are described and discussed in relation to the taxonomy and zoogeography of the species.

Factor analyses have been carried out on the total data for 134 planktonic forms sampled during the 1965 SOND cruise by R.R.S. ‘Discovery’. Species assemblages are largely consistent with the intragroup analyses carried out previously (Angel & Fasham, 1973). Factor score plots for the separate day and night series confirm the rather limited number of categories of vertical distribution patterns that occur despite the occurrence of vertical migration. The analysis of the combined day and night data confirms the rather limited number of patterns of vertical migratory behaviour. Size spectra of euphausiids in some of the assemblages associated with each category suggest that there may be resource partitioning. The trophic relationships within the assemblages appear to be structured and are discussed in the light of the limited knowledge of the feeding behaviour of many of the species involved. Diurnal vertical migration behaviour in planktonic species appears to be limited to the top 700 m.

The results of morphometric and developmental studies made to elucidate the relationship between Parathemisto gaudichaudi (Guerin) and P. gracilipes (Norman) show them to be one and the same species. Apparent differences are due to differences in the size of specimens at maturity, and to the degree of development of the bispinosa-compressa condition. P. gaudichaudi takes precedence over P. gracilipes.

The species is highly variable, existing in two extreme forms, the bispinosa form and the compressa form, together with all possible intermediates. The full range of the bispinosa-compressa condition is not expressed until a body-length of 10 mm is reached. Specimens are capable of changing towards either extreme at moults, but the factors causing the change are unknown.

A key to the genus Parathemisto Boeck is included.

The colour patterns of the corkwing wrasse Crenilabrus melops and the functional significance of these patterns has been described. The resting colours of the fish are described for juveniles, mature males and mature females. These colour patterns assist in making the fish less conspicuous in their natural environment. Agonist behaviour is characterized by the development of a series of vertical bars on the body together with ritualized lateral and frontal displays in aggressive, and a head-up submissive posture in fright situations. Most aggressive behaviour is associated with the territorial activity of the mature male. Courtship and spawning activities involve a complex series of visual signals that synchronize the roles played by the male and female. The differences in colouration between juvenile and mature fish and the changes any individual can display have wrongly lead earlier authors to split C. melops into different species or varieties.

A clear preference for the actinian anemones Actinia equina, Anemonia sulcata and Anthopleura elegantissima was demonstrated, while the acontian anemones and Corynactis viridis ranked low in the order of preference. The significance of acontia as defensive structures in anemones is discussed briefly. No differences in food preference were found between eolids collected from Plymouth and Millport; and British Aeolidia behaved in the same way towards Californian anemones as did Californian Aeolidia.

The eolids varied in their tendency to bite different species of anemone, but the performance of each individual eolid was similar in different experiments. It is possible that the individual variations may account for conflicting reports in the literature.

A small collection of cephalopod remains taken from 26 blue shark stomachs is examined. This includes 92 lower and 97 upper beaks which are identified as far as possible to species. From measurements of the beaks, mean weight and total weight of each cephalopod species is estimated. The presence of oceanic cephalopod remnants in the stomach contents indicates that some sharks caught in the Looe area had recently migrated inshore from deep water.

A small collection of cephalopod beaks from the stomach of a sperm whale caught off Vigo is described, identified and the weight of cephalopods represented is estimated. Comparisons are made with a similar collection previously described from a whale caught off Madeira.

A total of 618 cephalopods comprising 29 identified species and 98 young unidentified larvae were collected at 30° N 23° W in opening–closing rectangular midwater trawls (RMT combination net), an Isaacs Kidd midwater trawl equipped with an openingclosing bucket and a British Columbia midwater trawl. Discrete horizons were fished between the surface and 2000 m and day and night vertical distribution for the more common species is described. Material is sufficiently abundant to draw tentative conclusions on the vertical distributions of 16 species. These show a wide variety of migratory and non-migratory behaviour including diel migration, ontogenetic migration and static distribution at various depths and over various depth ranges.

Two new species of cranchiid cephalopod are described. These were both collected by opening-closing midwater trawls (RMTs) when vertical series were fished in the North Atlantic from R.R.S. ‘Discovery’.

Eighty-seven specimens of Bathothauma lyromma from the ‘Discovery’ collections have provided new information on this unusual species. The size range represented is sufficient to trace the development from small larvae to near adult. Information on sexual development is also given. Twenty-nine specimens from opening-closing nets show that Bathothauma occupies the depth range 100–1250 m, with smaller specimens living at shallower depths than the larger ones.

The biochemical composition of three batches of Ostrea edulis L. spat was determined during post-settlement growth. The spat were from spatfalls in January, March and June. For the first few months after settlement the neutral lipid (triglyceride) content was greater than the glycogen content. However, in three- to five-month-old spat the glycogen content became greater than that of neutral lipid.