INTRODUCTION

The problems involved in the identification of freeliving marine nematodes have stood in the way of ecologists for some time. Although considerable advances are now being made on the continent (particularly in Kiel Bay and the Mediterranean) and in North America, our lack of knowledge of the British species is still lamentable. In order to rectify this state of affairs to some extent, a study of the distribution of nematodes in the Exe estuary was planned to cover as wide a spectrum of physical and chemical conditions as possible, ranging from fine muds with a low interstitial salinity at the head of the estuary to coarse sands with a high salinity at the mouth. It is hoped that the characterization of the fauna of various habitats in the estuary will form a basis for further ecological studies in other areas. Not surprisingly, a large proportion of the species found were new British records, and some new to science. The fourteen species of this latter group discussed in this paper are described elsewhere (Warwick, 1970).

The anatomy of the teleost lymph system is considered in relation to the observed flow of lymph. The plaice Pleuronectes platessa L. was studied.

The vessels described by anatomists as longitudinal ventral, dorsal and lateral lymph ducts do not pass lymph to the head but act as collecting sinuses; the lymph flows from these sinuses to the neural lymph duct via the interspinal ducts.

At the junction of each interspinal duct and the neural lymph duct there is a simple valve. Lymph drains through this system as a result of a negative pressure developed in the neural canal by the respiratory movements of the gill apparatus.

The rigid nature of the neural lymph duct and the valves where the interspinal ducts join it allow the negative pressure to develop from a negative positive gill generated pres-sure cycle in the cephalic lymph sinuses. Valves Unking cephalic lymph sinuses aid the return of lymph to the duct of Cuvier using the same pressure cycles.

The drainage system is different in the salmonidae where the neural lymph duct is degenerate and the network of peripheral ducts serve as lymph return ducts. This can probably be explained by the occurrence of higher circulation pressures in the salmonidae.

Lymph from the neural lymph duct is a clear fluid having a composition similar to that of blood plasma. Like blood, lymph clots, and contains normal blood levels of mobile leucocytes and thrombocytes and lymph reflects blood levels of lactate. Lymph contains nearly no erythrocytes and the protein concentration of neural duct lymph is 80–4% that of blood plasma.

INTRODUCTION

Dinoflagellates have often been held responsible for a large part of the phosphorescence of the surface waters of the sea. In temperate waters, dinoflagellates are seldom the most abundant constituents of the phytoplankton, and until recently little experimental evidence has been available to support this assertion. Until recently there have been few careful attempts to determine which particular species of dinoflagellates are luminescent, or to relate total luminescence to numbers of dinoflagellates present.

Mesopeiagic fish without swim bladders, found in depths from 100 to 1000 m, have soft bodies with a very high water content (88–95%) low haematocrits (5–9%), smallhearts, a low proportion of red muscle, and large lymph ducts. Species possessing swim bladders have a lower water content (70–83%), higher haematocrits (14–35%), larger hearts, more prevalentred muscle and smaller lymph ducts. Some active surface species have still less water (64–74%) and higher haematocrits (48–57%).

The soft watery fish appear to use skeletal reduction and high water content asa buoyancy mechanism but there is no evidence, judging from analyses of freezing-point depression of the plasma and muscle fluid, that they maintain an extra low ionic content to assist buoyancy. Although oxygen is probably adequate in the deep water, there may be some constraint on activity because the oxygen-carrying capacity ofthe blood is low and oxygen may be limited at the tissues. This is partly compensated for by the high proportion of anaerobic white muscle and the large lymph system. These watery fish appear to be best adapted to short bursts of activity. Nevertheless they do make diel vertical migrations which may cause them to reach the limits of their aerobic metabolic systems.

The mesopeiagic species with swim bladders are much more similar in their circulatory characteristics to inshore fish. They also make quite substantial vertical migrations with the concomitant problem of adjusting buoyancy by varying the pressure within the swim bladder. Metabolically this is unlikely to be unduly difficult.

INTRODUCTION

Oxyrrhis marina Dujardin is among the few phagotrophic micro-organisms, and the only dinoflagellate with this mode of nutrition, to have been cultivated under axenic conditions. In common with most other phagotrophs studied, Oxyrrhis had to be supplied with a natural source of lipid growth factors for axenic cultivation, lemon rind or grass extracts in this instance (Droop, 1959). The eventual replacement of these natural sources by ubiquinone (Droop & Doyle, 1966) cleared the way for the development of a completely denned culture medium for Oxyrrhis and the completion of the nutritional study, the water-soluble nutrients having been fully worked out previously (Droop, 1959). However, identification of this requirement immediately raises two questions. The answer to the first, whether ubiquinone is the only lipid required, appears to be in the negative, and the details of an additional, fairly specific, steroid requirement are presented in the second part of this paper. The other question concerns the specificity of the quinone requirement. Is the quinone merely a convenient source of the benzene ring – mammals require at least one aromatic compound in the diet – or does it act as a true growth factor, in which case the requirement would be unique and would have more than protozoological interest?

INTRODUCTION

Initially the haptonema was recorded as a ‘little additional flagellum’ by Scherffel (1899) when he described Phaeocystis globosa. Similarly, the haptonema was referred to as the ‘third flagellum’ on the apparently tri-flagellate, brackish-water Prymnesium saltans Massart (Massart, 1920). Two further brackish water species of Prymnesium were described by Carter (1937) and all were characterized by a very short immobile ‘third appendage’. Lackey (1939) found a freshwater organism similar to Prymnesium but it possessed a ‘third flagellum’ several times the length of the true flagella. He re-corded that the third appendage was held out rigidly when the cell was at rest but during rapid swimming he was unable to see it and thought that this was due to an extremely rapid beat. He named his new organism Chrysochromulina parva and C. parva Lackey is now the type species of a considerable genus.

Parke, Manton & Clarke (1955,1956,1958,1959) made a study of the light microscopy and fine structure of numerous marine species of Chrysochromulina. Their results showed that the ‘third flagellum’ differed in appearance and structure from that of a true flagellum and hence they decided to call this organelle a haptonema owing to its thread-like form and its ability to adhere to a smooth surface (Parke, Manton & Clarke, 1955). Their observations revealed that the haptonema could attach to a surface by an ‘adhesive tip’ and that the majority of species could coil their haptonemata into a helix and extend it again. In some species, e.g. C. strobilus (Parke, Manton & Clarke, 1959), the haptonema was usually tightly coiled whilst the cell was swimming.

Prof. Jerzy Stanislaw Alexandrowicz, who died at Plymouth on 28 October 1970, was one of the most distinguished histologists of the nervous system, whose series of memoirs upon invertebrate peripheral nervous systems stimulated much physiological and histo-logical research. He was born at Stoczki, in Poland, on 2 August 1886, and after matriculating in Warsaw studied medicine and natural science at the universities of Warsaw, Zurich, Munich, Heidelberg, Paris and Jena. He took his Ph.D. at Zurich under Lang, and his M.D. at Jena, under Biedermann, serving for a short period as a surgeon in the Military hospital at Belgrade, before being appointed to the department of descriptive anatomy at Wilno. He remained here during the war, and in 1918 served with the field hospitals coping with epidemic diseases brought to Poland from the East. He himself survived an attack of typhus. In 1919 he was appointed to organize and direct the department of descriptive anatomy at Wilno, and the next year rejoined the army to serve as the chief medical officer of a cavalry regiment in the fighting against Russia.

In 1920 he returned to Wilno, as head of the department of histology, and remained there until 1929, when he moved to Lwow, again as director of the department of histology, in the Academy of Veterinary medicine. In 1933 he became Pro-Rector of the Academy, and in 1936 Reaor, finally leaving the university in 1937 to head the scientific and university department of the Ministry of Education. He quickly became Under-secretary of State for Education, and in 1938 relinquished this post to spend six months at the Stazione Zoologica, Naples, where he had previously worked on three occasions.

INTRODUCTION

Certain sand-dwelling amphipods occur either in the intertidal or in the sublittoral zone and extreme low-water springs (E.L.W.S.) has been taken as a convenient dividing line between these two habitats. Previous workers have concentrated mainly on one or other of these contiguous regions. General studies of the in-fauna of intertidal sand on the Isle of Man include those of Pirrie, Bruce & Moore (1932), Jones (1948) and Southward (1953). The in-fauna of sublittoral sandy deposits around the Isle of Man has been studied by Jones (1940, 1951, 1956) and Fincham (1969a). However, Mclntyre & Eleftheriou (1968) working at Firemore Bay, Loch Ewe showed that the intertidal and shallow-water sand regions should be regarded as a unit. Faunal distributions were not always discontinuous about E.L.W.S.

INTRODUCTION

The black scabbard fish, Aphanopus carbo Lowe, is an elongate mid-water trichiurid, which is caught commercially off Madeira, and has been recorded, though infrequently, from British waters (Tucker & Palmer, 1949; Tucker, 1956). Twelve specimens were caught during a recent cruise of R.V. ‘Sarsia’ in the Biscay area (Forster, 1970), and this note reports observations on their behaviour, histology and anatomy, which suggest that these fish are highly specialized for a particular method of catching prey.

INTRODUCTION

Recent experiments with symbiosis in the flatworm Convoluta roscqffensis Graff (Provasoli, Yamasu & Manton, 1968; Provasoli, Yamasu & Mabuchi, 1969) reveal an important area in the investigation of algal-invertebrate associations, demonstrating the potential of studies based on the principle of cross-infections using various experimental symbionts. The studies which these authors describe are feasible only if detailed taxonomic data are available to facilitate rapid identification of symbionts in situ. This kind of experimentation is impossible in symbiotic systems involving ‘zooxanthellae’, because of the general failure to provide adequate descriptions of the genera and species included in this ill-defined group. Admittedly, the situation shows signs of improvement. We now know that the ‘zooxanthella’ associated with C. convoluta Abildgaard is a diatom belonging to the genus Licmophora (Ax & Apelt, 1965; Apelt, 1969), the morphological criteria for the identification of Symbiodinium microadriaticum Freudenthal have been redefined (Taylor, 1969 a) and a revised taxonomic description of this species is now available (Kevin, Hall, McLaughlin & Zahl, 1969). Nevertheless, we are still a long way from achieving a representative collection of well known experimental symbionts for use in comparative studies. It therefore seems worthwhile (not merely an exercise in micro-taxonomy and micro-horticulture) to continue to collect, identify and describe the range of genera and species that may be hidden among the ‘zooxanthellae’. The present paper is one in a series (see Taylor, 1969 a, b, c) intended to explore the potential variety of these organisms.

INTRODUCTION

Balanus balanoides (L.) is a cross-fertilizing hermaphrodite. Insemination takes place in November in North Wales. Spermatozoa are deposited in the mantle cavity of a receptive individual by the extended penis of a neighbouring ‘acting male’. If a receptive individual – that is one that will accept insemination – is examined before oviposition takes place, the oviducal glands are found to be distended by a clear fluid (Walley, 1965). Oviposition follows insemination and fertilization is external, taking place within the confined space of the mantle cavity. The oocytes enter the mantle cavity, via the paired oviducal glands, and become enclosed in a pair of thin membranes. These membranes, enveloping the egg masses, are formed by distension of the elastic sacs secreted by the oviducal glands (Walley, 1965) and the spermatozoa have to pass through them in order to fertilize the eggs. If spermatozoa which have been deposited in the mantle cavity of a receptive individual are removed and examined before oviposition begins, they are immotile. If, however, they are examined several minutes later, during oviposition, they are found to be swimming vigorously (Barnes & Crisp, 1956): they have apparently been activated. The work described in this paper yields some information on the activation of the spermatozoa in B. balanoides, supplements recent work on the structure of cirripede spermatozoa (Brown, unpublished2; Turquier & Pochon-Masson, 1969; Bocquet-Vedrine & Pochon-Masson 1969; Munn & Barnes, 1970), and fixes the time within the sequence of maturation divisions of the oocyte at which fertilization takes place.

While it is known that the hydroid Clytiajohnstoni (Alder) may get broken off and drift in the plankton (Russell, personal communication), rounding off into pelagic colonies, there is, however, no record of the hydroids Sarsia tubulosa (M. Sars) and Tubularia larynx (Ellis and Solander) living under similar conditions.