Pillai (1970) proposed that the Spirorbidae form a distinct family and, though closely related to serpulids, they are indeed more surely separate than many families of birds and insects. Their study in Britain was well begun by Montagu (1803), with so much ecological detail that most of the species in his account (about ten) can be recognized by anyone who is really familiar with the marine fauna of Devon. All the names which he used, however, have lapsed or been applied otherwise, except Spirorbis spirorbis L. and even that has often been called S. borealis. Some of the nomenclature of McIntosh (1923) has similarly lapsed, because it conflicted with clear descriptions by French and Scandinavian authors, including Fauvel (1927).

The ciliates are considered to be the dominant protozoan group in the lacunar system of marine sediments and the important role which they play in the benthic ecosystem has been emphasized (Fenchel, 1969). More than 7500 ciliate species have been described (Corliss, 1974 a) and their distribution is worldwide (Agamaliev, 1967 a; Burkovsky, 1970c; Dragesco, 1960, 1965a; Kahl, 1930–35; Petran, 1967; Raikov, 1962). However, only two surveys of the interstitial ciliates of the British Isles have been carried out (El Maghraby & Perkins, 1956; Lackey & Lackey, 1963). This paper describes a study of the systematics and ecology of interstitial ciliates of the North Yorkshire coast.

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).

The taxonomy and distribution of sipunculan species in the shallow-water zone (< 200 m depth) of European seas are fairly well-documented. One notable exception is Phascolosoma intermedium, a small-sized species described by Southern (1913 a) from material dredged off the west coast of Ireland at 44–143 m depth. Since its description, no further specimens of P. intermedium have been reported in the region and the species was not considered by Stephen (1960) in his synopsis of the British species.

Among the teleosts three basic modes of locomotion have been recognized; anguilli-form, carangiform and ostraciiform (Breder, 1926). During the past 50 years much attention has been paid to the anguilliform (Breder, 1926; Gray, 1933 a, b; Gadd, 1952; Taylor, 1952; Lighthill, 1960, 1969, 1970) and carangiform (Breder, 1926; Gray, 1933 c; Bainbridge, 1958, 1960, 1963; Lighthill, 1969, 1970) modes. In contrast little work has been done on the ostraciiform mode. Models have been made along mechanical (Breder, 1926; Gray, 1968, p. 35) and mathematical (Smith & Stone, 1961) lines. How-ever as Gray (1968) points out, ostraciiform locomotion has not been analysed in living fish.

It is our aim in this paper to answer three questions. All of them relate to the well-known ability of lugworms to act as isosmotic osmo-conformers over a wide range of salinities. When exposed to diluted sea water, the body fluids come into osmotic equilibrium with the lowered external concentration, and considerable amounts of water enter the body of the worm. There is no evidence of weight or volume regulation in dilute media, as assessed by a return of the body weight towards its original value. The processes of osmotic adaptation down to the lowest salinity limits for survival include, therefore, tolerance of a lowered osmotic concentration of the body fluids, and of the retention of increased amounts of water in the body. The evidence on which this view of osmotic adaptation in lugworms is based is reviewed by Oglesby (1969, 1973). Additional information on Arenicola marina is provided by Freeman & Shuttleworth (1977).

In February 1965 larvae of Sabellaria spinulosa Leuckart removed from the plankton off Plymouth were reared for settlement experiments (Wilson, 1970b). Among the early stages in the rearing dishes there appeared several Sabellarian-type larvae which after a few days growth became conspicuous by their larger size, longer and straighter bristles, and by their general appearance being different from the more numerous Sabellaria larvae. It soon became apparent that they closely resembled a larva found in February 1927 which was described and illustrated many years ago (Wilson, 1929, p. 242, text figs. 4, 5), at which time it was attributed in all probability to Pallasia murata Allen, now Lygdamis muratus (Allen). Apart from two species of Sabellaria whose larvae were known, this was and still is the only other Sabellarian recorded from the coasts of Devon and Cornwall and adjacent offshore waters of the English Channel. In most years since 1965 varying numbers of this species of larva have been obtained in January and February, and have several times been reared through metamorphosis to early tube-building stages, these latter confirming by their distinctive characters that the above early attribution was correct. Work on a description of the development was begun but it was not until 1974, when work on colony formation of Sabellaria alveolata (L.) was virtually completed, that close attention could be given to it, and experiments on settlement carried out. In the meantime Bhaud (1969) had described and illustrated the development from larvae in winter plankton off Banyuls-sur-Mer, wrongly attributing them to Phalacrostemma cidariophilum Maranzella, while criticizing my identification of my 1927 larva.

The spermatophore in the Copepoda is an elongated flask-shaped object produced by the male copepod in which are contained the sperm and associated secretions. The male must attach the spermatophore to the female genital segment in such a position that the opening to the neck of the spermatophore, through which the sperm come out, is in contact with the opening of the female cavity. Placement of the spermatophore elsewhere, in such a manner that connexion with the female genital cavity is not achieved, may not cause fertilization and will waste sperm.

There has been some confusion over the past 150 years or so concerning the correct combination to be applied to the single species of hydroid variously known as Arum cocksi, Myriothela phrygia and M. cocksi. The correct binominal would seem to be Candelabrum phrygium, a combination first used by de Blainville (1830) but hardly used since. An attempt by Stechow (1921, 1922, 1923) to re-introduce this combination has apparently been unsuccessful. The synonymy relevant to the genus name is as follows. To avoid repetition some information more relevant to the nomenclature of the species name is also included here.

In an attempt to identify the causes of the natural population fluctuations on British rocky coasts, an exploratory programme on the recruitment fluctuations of certain ‘key species’ has been operating for several years. The choice of species and the emphasis upon their recruitment have been discussed elsewhere (Lewis, 1976) and were justified as the most economical means of gaining the ability to (a) ‘explain’ major changes in the general character of rocky shore communities, and (b) make predictions about natural events against which to detect regional or temporal consequences of man-made changes in water quality. Mussels, barnacles and limpets are being studied but it is the last with which most interpretative progress appears to have been made, and this paper is concerned solely with Patella vulgata L. It is, however, essentially a preliminary report in a continuing study and it illustrates the practical and interpretative problems inherent in formulating and substantiating hypotheses in this type of work.

The saithe, Pollachius virens (L.), makes substantial diel vertical migrations like many other teleost fish. Adulst saithe offshore are known to ascent at dusk from 100 to 10 m (Schmidt, 1955) during which they experience a pressure decrease from 11 to 2 atm. If the swimbladders of these fish were fully adapted to the daytime depth, the gas of the swimbladder (which ‘obeys’ Boyle's Law) would expand 4½ times and rupture the swimbladder wall (Tytler & Blaxter, 1973). Even if not fullly adapted it is likely that some increase in volume would be experienced, giving not only the danger of the swimbladder bursting, but also a serious equilibrium problem as the fish become more positively buyant during the ascent. Jones (1952) for example suggested that the physoclistous perch adapted to a particular pressure could only cope with a 33% decrease in pressure without rising to the surface out of control.

A population of the two species, Nephtys hombergii Savigny and N. caeca Fabricius, has been studied for a period of 3 years. Three separate but related aspects of the biology of these species have been investigated; gametogenesis (Olive, 1976a, and in preparation), reproductive endocrinology (Olive, 1976 a, b) and the life-history and population structure which is the subject of the present report. Nephtys species are particularly interesting for studies of this kind since Kirkegaard (1970) described rings in the teeth of N. hombergii which were thought to represent annual growth rings. Estcourt (1975) has found that these rings can be used to age the nephtyid species Aglaophamus verrilli in New Zealand which is a slow growing species living to at least 5 years of age. The degree of overlap between the successive generations, as indicated by the rings in the teeth, emphasizes how difficult age analysis of populations with this type of growth is without additional information of this kind. This problem is particularly acute in long lived polytelic (= iteroparous, Gadgil & Bossert, 1970) species. Olive (1975) has discussed the problem with reference to Eulalia viridis and other recently investigated polychaetes but it is not peculiar to Polychaeta as, for instance, Lewis & Bowman (1975) have shown in a particularly detailed study of populations of Patella vulgata.

Temperature, salinity and nutrient structure at a station, E1, in the English Channel 22 miles from Plymouth have been described for many individual years (see Armstrong & Butler, 1968, for example). By averaging the results gathered over many years (1903–61) the mean seasonal changes in the vertical distributions have been obtained (Pingree & Pennycuick, 1975). In this paper these distributions have been extended to incorporate data to 1975 and as well as presenting up-to-date mean distributions for temperature, salinity and inorganic phosphate, the mean distributions for silicate and nitrate are included. The purpose of the present work is to interpret the observed mean seasonal changes in the inorganic nutrient distributions in the light of recent measurements giving continuous variations of chemical properties (Armstrong & Lafond, 1966), and in particular, from the knowledge gained from continuous vertical chlorophyll ‘a’ determinations (Lorenzen, 1966; Holligan & Harbour, 1977; Pingree, Holligan & Head, 1977).

As Moseley (1879) noted, it may be imprudent to assume there must always be a ‘reason’ for observed displays of bioluminescence. However, knowledge of the colour of the light emitted may be useful for examining some of the theories about the function of marine bioluminescence. Certainly the colour of the light is important in predicting the rate of its attenuation in sea water, and the ease of perception of the light by the organism itself, or by potential predators, prey, or mates. In addition, the colour of the light may indicate something about the compounds responsible for producing the light. The present paper presents some bioluminescent emission spectra of freshly caught organisms from the Sargasso Sea.

The polychaete Capitella capitata (Fabricius) has become well known amongst marine biologists as an indicator of polluted conditions, especially those due to organic enrichment. Reish (1959) mapped zones in a polluted harbour and correlated the presence of C. capitata with the polluted region. Bellan (1967) and Cognetti (1972) drew similar conclusions and Henriksson (1969) describes the species as a bacterial pollution indicator. Pearson (1975) records its presence in areas enriched by pulp mill effluents and Rosenberg (1972, 1973) notes its importance in the pioneer community developing after the closure of a pulp mill.

Many of the calanoid copepods contain large amounts of neutral lipid that is predominantly wax esters (Lee, Hirota & Barnett, 1971; Lee & Hirota, 1973; Sargent & Garten, 1976). The role of these compounds in the life-history of copepods is particularly well documented for the large Northern Pacific calanoid Euchaeta japonica Marukawa. These animals have their highest levels of total lipid (50% of the dry weight) at stage V, up to 80% being wax esters (Lee, Nevenzel & Lewis, 1974). Wax ester levels are lower in adult females but are high in the eggs, the contents of which are subsequently used during the naupliar stages (Lee et al. 1974). Thus, wax esters accumulated during the later developmental stages provide a fuel for the developing eggs and embryos; from which it follows that the amounts of these lipids present in mature animals are likely to be critical in determining the brood size and survival of the ensuing generation. So far, however, the factors controlling lipid levels in copepods have been poorly understood.

The development of sensitive fluorimetric techniques for continuous in vivo measurements of chlorophyll ‘a’ (Lorenzen, 1966) has made it possible to study in detail the vertical distribution of phytoplankton in lakes and seas (e.g. Strickland, 1970; Berman & Pollingher, 1974; Lasker, 1975; Fasham & Pugh, 1976; Pingree et al. 1976). However, for marine environments there is little compatible data, such as given by Lasker (1977), on the species composition of localized phytoplankton populations. This is an important gap in our knowledge since the variations shown by different algal taxa in attributes such as nutrient requirements, growth rates, adaption to light, and palatability to zooplankton have wide ecological implications.

The ability of the slipper limpet Crepidula fornicata L. to feed on suspended particles carried into the mantle cavity by cilia on the gill has attracted attention for many years since the feeding mechanism was described by Orton (1912). Subsequent studies were made on the possible origins of this mode of feeding (Yonge, 1928, 1938), and later Werner (1951, 1952, 1953, 1955, 1959) made more detailed observations on the mechanisms by which particles are retained by the animal. He showed that coarse particles are strained by means of a mucus filter covering the inhalant aperture to the mantle cavity, whilst the majority of the medium and fine particles are entangled by a second mucus filter secreted by an endostyle and which lies against the frontal surface of the gill (for review, see Jørgensen, 1966; Newell, 1970).

The oceanic sunfish Mola mola is occasionally found close to our shores, its normal habitat being the oceans throughout the world. It is replaced by Mola ramsayi only in the South Pacific (Fraser-Brunner, 1951). Specimens which are caught around the British Isles normally come from the North Atlantic as a result of being washed inshore when the warm westerly winds are blowing during the summer.

This paper is concerned with a re-examination of the pattern of nerve activity from receptors in ray fin muscles in response to stretch applied to the muscles. In earlier work receptors have been found in the fin muscles of elasmobranchs, those in rays being described in a recent paper by Bone & Chubb (1975 - which see for references to earlier anatomical work) and physiologically by Fessard & Sand (1937). The receptors are supplied by myelinated axons, and the endings take the form of beaded nerve strands associated with congregations of connective tissue lying between muscle fibres. In the pectoral fin muscles these structures lie between small-diameter muscle fibres, with multiple motor nerve endings, which occur superficially in the muscle. Most of these muscle fibres show a positive staining reaction for succinic dehydrogenase (SDH) and lipid, though some are negative for SDH. They contrast with the larger fibres, which show negative staining reactions for SDH and lipid, andhave focal motor innervation. The latter make up the bulk of the muscle (Bone & Chubb, 1975). It seems very likely that most of the small fibres are slow contracting (possibly with no propagated action potential in the muscle fibre), and the large fibres are of a twitch type. This would parallel the arrangement in dogfish myotomes (Bone, 1966). Bone & Chubb consider the coupling between the endings and the muscle fibres to be generally loose, although they also describe occasional sites of much tighter coupling. Such small muscle fibres are particularly concentrated in a superficial and rather discrete part of the muscle, here called the tonic bundle and used in the present experiments as an isolated preparation.