The head of the sperm whale (Physeter macrocephalus L.), which is largely snout and the crest of the skull necessary to support it, may exceed a third of the total weight and a quarter of the length of the whale. This indicates the snout has an extremely important function but few theories regarding its function take into account the overall structure, whilst the detailed structure and proportions of the adult's snout have been almost totally neglected. Similarly, consideration of the thermal properties of the spermaceti oil, which is the most remarkable component and constitutes a large proportion of the head, have been neglected in studies of function.

This is the second of three papers describing the structure, properties and buoyancy function of the spermaceti organ of the sperm whale (Physeter macrocephalus Linnaeus 1758). The first paper (Clarke, 1978a) described the detailed structure and proportions of the spermaceti organ and related structures and considered relevant details of the blubber, skin and lungs. Here, three thermal properties of the spermaceti oil are described which are relevant to a study of the function of the oil. Finally, in a third paper (Clarke, 1978b) it will be shown that, over its great geographical and depth ranges, the whale varies considerably in buoyancy due to variations in water density and the volume of air in its lungs and it is suggested that, during dives, the whale can control its own density by changing the temperature of the spermaceti oil of the head and may attain neutral buoyancy in dives deeper than 200 m.

This paper will discuss the buoyancy of the sperm whale throughout its range and show that the whale probably has some control over its own buoyancy. Evidence will then be presented in support of the hypothesis that the whale can attain neutral buoyancy at depths greater than 200 m by control of the temperature of the spermaceti oil in its head. As a basis for this, papers describing the detailed structure and proportions of the whale (Clarke, 1978a) and some physical properties of spermaceti oil (Clarke, 1978b) have already been published.

Little is known about the swimming of fish in which flexures of the body and caudal fin are not the main means of locomotion. Breder (1926) provides brief descriptive accounts and a useful classification of the main non-body modes of locomotion in teleosts. These are discussed in general terms by Harris (1937, 1953), Marshall (1965, pp. 31–41) and Lighthill (1969).

The myxinoid cyclostomes, of which the hagfish Myxine glutinosa L. is one of the best known examples, are of unique biological interest as representatives of a group of jawless vertebrates which probably had their origin in the pteraspidomorph ostracoderms of the Ordovician era (Nybelin, 1973). They have been much studied by comparative anatomists and physiologists but somewhat neglected by ecologists. There is, for instance, very little critical information on their normal feeding biology. Perhaps one reason for this is that, although hagfish may be extremely abundant locally (their principal habitat requirements are stable, soft muddy sediments and a salinity in excess of 31 %, (Gustafson, 1935)), they tend to be missed by most exploratory fishing and biological sampling programmes. This is because benthic sampling techniques are often ill-adapted for the capture of large active organisms capable of swimming and burrowing and because, unless blocked by the catch, the cod-end mesh sizes of the trawls used by most British commercial fishermen would easily permit the escape of even the largest hagfish. However, the research otter trawls used by the Department of Agriculture and Fisheries for Scotland (D.A.F.S.) for surveying the North Sea stocks of the deep water pink shrimp, Pandalus borealis Krøyer, are fitted with cod-end covers of small mesh, and it is found that the catches frequently include small numbers of hagfish, presumably caught while swimming close to the bottom, or possibly when buried in the surface of the sediments. The present study is largely based on the examination of hagfish collected during the D.A.F.S. Pandalus surveys of 1975 and 1976. The remaining material was kindly provided by Dr J. B. Buchanan of the Dove Marine Laboratory at Cullercoats, Northumberland.

While examining collections of young fish taken with a 2 m stramin net on the west coast of Scotland in 1975 for the unstaffnage Marine Research Laboratory of the Scottish Marine Biological Association I found two postlarvae unlike any I have seen before.

These two specimens, both about 6.2 mm long, were taken on 31 July 1975 from the Tiree Passage between the Islands of Mull and Tiree, and from Bloody Bay on the south-west coast of Mull.

The bivalve mollusc Scrobicularia plana (da Costa) is very common in the estuaries of South-West England and lives in permanent burrows in intertidal sediments ranging from soft mud to fairly hard sand and sometimes gravel. Although it obtains some of its food by filtering the overlying water, Scrobicularia is mainly a deposit feeder (Hughes, 1969). In addition to its widespread distribution, Scrobicularia has several features which make it attractive as a possible indicator organism for metallic contamination. It is more tolerant of low salinities than most common estuarine bivalves, usually penetrating farther upstream than Macoma balthica, Mytilus edulis and Cerastoderma edule (Percival, 1929; Spooner & Moore, 1940; Bryan & Hummerstone, 1977). Also, it lives for over ten years, usually attaining a length of 4–5 cm, and its rate of growth can be estimated from rings on the shell (Green, 1957; Hughes, 1970).

The majority of studies of the physiological ecology of organisms have been concerned with changing a single environmental variable at a time, but more information on the relationships between biological responses and environmental factors would be provided by experimental techniques that emulate the multi-dimensional character of the natural environment.

In nature, organisms are subjected to a variety of environmental factors acting together and they respond to the total resulting stimulus rather than to single environmental variables. In addition, the animal's response is not in terms of individual physiological rates but rather as a whole organism. Therefore an experimental approach to an animal's response to a complex environment could usefully include (a) multivariate experiments and (b) integration of individual physiological processes to provide a greater under-standing of the ‘whole organism’ response. In this paper, non-linear multiple regression equations and response surfaces are used to describe and illustrate the combined effects on the common mussel, Mytilus edulis L., of body size, ration and season on physio-logical integrations such as the scope for growth, growth efficiency and the oxygen: nitrogen ratio (reviewed by Bayne, 1975; Bayne, Widdows & Thompson, 1976). The data used to compute these physiological integrations are derived from a series of multivariate experiments described in a preceding paper (Widdows, 1978).

The bryozoan benthos of the European continental slope is attracting attention after a long period of neglect. Expedition reports, such as those of the ‘Challenger’ (Busk, 1881, 1884, 1886; Waters, 1889), ‘Travailleur’ and ‘Talisman’ (Jullien, 1882; Calvet, 1906), and ‘Hirondelle’ (Jullien & Calvet, 1903) made important contributions to our knowledge. Such monographs have been supplemented by shorter papers dealing with the Bryozoa of offshore banks and island groups (Guérin-Ganivet, 1911; Norman, 1909) or of limited areas within the European region (Duerden, 1893; Nichols, 1911). Following the recent increase of interest in offshore benthos generally, the papers of d'Hondt (1970, 1973a, b, 1974, 1975) provide much new information on the slope and outer shelf bryozoan fauna. However, many of the often enigmatic species of earlier authors have yet to be redis-covered, and d'Hondt has shown that a high proportion of the Bryozoa collected comprises species new to the area or new to science. Clearly, the study of many more collections will be necessary before any comprehensive account can be given.

The fact that Spirorbis spirorbis (= S. borealis) has a summer breeding season during which several successive broods of larvae are produced has been known since the work of Garbarini (1933,1936). A recent summary of the taxonomy, ecology and distribution of S. spirorbis has been given by Knight-Jones & Knight-Jones (1977). The two aspects of the species' reproductive biology which have received most attention are the role of sea temperatures in initiating breeding and the correlation of brood production with lunar and tidal cycles. In the present work a study has been made of gametogenesis as well as of the more easily observed cycle of brood production. The results obtained have indicated, in respect of one population of S. spirorbis at least, the need for a major re-assessment of earlier studies of the species.

So few data are available concerning polychaete fecundity that recent speculation about the relative advantages of different life-history ‘strategies’, and about the relative value of protected and unprotected larval development, has been almost completely abstract. The dangers of this approach have been clearly indicated by Stearns (1976) in his recent review. Until quantitative studies are made of the number and weight of gametes produced in relation to the weight of individuals for a range of species, there seems little basis for discussion of the problems mentioned above.

The interest in the temporal variability of the Northumberland benthos derives from a continuing time-series of samplings initiated in January 1971. Intensive sampling was started at a single station for the purpose of computing the secondary production for the years 1971–72 (Buchanan & Warwick, 1974). It became clear in the course of this exercise that there was a considerable degree of variation in species numbers and ranking, both between the two years and, seasonally, within single years. Sampling at this station was continued for a further two years - 1973–74 – and the data were interpreted as an un-broken rising trend in numbers of individuals with changes in species ranking and diversity (Buchanan, Kingston & Sheader, 1974). Since the magnitude of change over the four years was unexpectedly high, and largely unexplained, it was decided to continue the observations for an indefinite period and to expand the programme of sampling to cover several stations over a wider area of different sediment types.

It is well known that if a beaker of water, to which a little sand has been previously added, is stirred, then the sand moves along the bottom and accumulates in the centre. The result is the same whether the beaker is stirred clockwise or anticlockwise. It is perhaps less obvious, but equally true, that if the beaker is placed on a rotating table, then stirring clockwise and anticlockwise produces different effects. Any stirring rate in the sense of rotation may produce a concentration of sand towards the centre (better effects may be observed with less dense material – tea leaves for example). However, if the stirring is against the rate of rotation, then it is necessary to exceed the rotation rate before sand will accumulate in the centre of the beaker. In an analogous manner, ‘spinup’ of the table produces dispersion of bottom material, whereas spin-down results in a concentration of material towards the centre of the beaker.

There are numerous examples of symbiotic associations between Foraminifera and unicellular algae. Most of these Foraminifera are larger Foraminifera which occur in the shallow, oligotrophic waters of tropical seas (Table 1). Some of the symbiotic algae have been studied by light microscopy (Table 1, nos. 1–6). Dietz-Elbrächter (1971) suggested that the symbionts of Heterostegina depressa might be diatoms. She was, however, unable to prove this statement satisfactorily. Hottinger & Dreher (1974) published electron micrographs of the symbionts of H. depressa and Operculina ammonoides. From these micrographs identification of the symbionts was not possible. To date, only the symbionts of the following Foraminifera have been classified by electron microscopy:Archaias angulatus, Sorites marginalis, Globigerinoides ruber, Hastigerina pelagica and Globigerinoides sacculifer (Table 1, nos. 7,10,12,13,14).

This study of the genus Pterosperma followed on from our work on the genus Halosphaera (Parke & Adams, 1961; Parke & Hartog-Adams, 1965; Boalch & Mommaerts, 1969) since while studying the latter we found abundant pterospermatacean material. In recent books on algae the family Pterospermataceae Ostenfeld (1902) is placed in the class Chrysophyceae (Papenfuss, 1955; Bourrelly, 1957, 1968; Fott, 1959, 1971; Prescott, 1969). The family, however, rightfully belongs in the class Prasinophyceae (Parke in Parke & Dixon, 1964, 1968; Christensen, 1966) in the order Pterospermatales (Parke & Green in Parke & Dixon, 1976).