In 1971 and 1972 during the course of short cruises to the South Biscay area on R.V. ‘Sarsia’ several hauls were made with a 100 hook long-line on the Continental Slope at depths ranging from 800 to 3600 m. The hooks used were of two different patterns (Fig. 1) arranged alternately. The hooks were mounted on wire snoods of about 1 m length which were attached to the line at 10 m intervals by stainless-steel snap-on connectors. The object of this arrangement was to find out if the incurving hook pattern based on a traditional South Pacific type of wooden hook showed any advantage over a normal type of hook.

Stromateoid fishes form a small group among the Perciformes, characterized by remarkable toothed saccular outgrowths in the gullet just behind the last gill arch (Haedrich, 1967). Most are associated with medusae when young but are poorly known as adults. In addition to the diagnostic oesophageal teeth, a striking feature of many stromateoids is the curious subdermal canal system, whose function is unknown and whose structure has not been described in detail. The present note describes observations upon the biology of Schedophilus medusophagus Cocco, and upon the structure of its integument.

Although the anatomy of the coelacanth muscles has been examined very thoroughly, their protein composition has, until recently, not been investigated. Thanks, however, to the 1972 British–French–American expedition to the Comores, frozen material has been made available and some results on myoglobin and four glycolytic enzymes have already been published. We have carried out a comparison of the sarcoplasmic proteins of red and white muscle by starch-gel electrophoresis. The ninhydrin-positive dialysable constituents and the myofibrillar proteins of white muscle have also been examined.

A few puzzling results obtained with the white muscle extracts have been related to the occurrence of o.1 M ammonia, due presumably to the splitting of urea by a bacterial urease, and to an alteration of the active thiol groups of GAPDH and PK. If due account is taken of these unusual post-mortem changes, the extractability of the proteins and their properties are strikingly similar to those of teleosteans. The comparison of the sarcoplasmic proteins of white and red muscle by starch-gel electrophoresis revealed also that the differentiation observed in the coelacanth was similar to that occurring in the carp. A study of the low-molecular-weight proteins, or parvalbumins, of white muscle and of the myofibrillar proteins also shows the expected differences between the two muscle types.

The only abnormal features observed in this study were the high concentration of parvalbumins, 1.5–2 times that found in other species examined, and the occurrence of an unusual globulin fraction which was easily extracted at ionic strength 0.5 and insoluble at ionic strength 0.35 and neutral pH.

Growth of the littoral harpacticoid copepod Tigriopus brevicornis O. F. Müller was measured in an intertidal rock pool. The generation time at the field temperature of 15°C was 31 days, and growth during this period resulted in an increase of 1.1829 μg body nitrogen.

Measurements of nitrogen excreted by developmental stages were made on animals removed from the natural population. Ammonia comprised on average 89.7% of the total nitrogen excreted by adults. Some measurements of phosphorus excretion indicated a nitrogen: phosphorus ratio in excretory products of 4.86. Adult females excreted 27.2 μg N/mg dry wt/day, representing a release of about 30% of body nitrogen daily. Excretory rates of earlier copepodite and naupliar stages were higher.

The efficiency with which ingested food was assimilated was measured for animals feeding on natural suspended matter obtained from the pool. Assimilation efficiencies averaged 75.4%.

Egg production was measured at a range of temperatures in the laboratory, enabling an estimate to be made of total production by an individual female. At 15°C females produced an average of ten egg sacs in 30 days.

Measurement of nitrogen lost during moulting suggested a value of 6% of total body nitrogen.

The data obtained have been used to estimate growth efficiency in terms of nitrogen during the entire life-history of a female in the pool. Gross growth efficiency calculated for the period of growth from egg to adult is 13.0% and the net efficiency 17.2%. Efficiencies of egg production by the adult female are higher, the gross efficiency being 22.1% and the net 29.3%. During the entire life-span 72.9% of assimilated nitrogen is expended in metabolism, 3.9% in growth, 0.4% as moults, and 26.6% in egg production.

All species of the Mysidacea (Crustacea) lay their eggs into a marsupium, thus allowing direct counts of brood sizes to be made. The different forms of the young stages in the marsupium are closely similar in all species. The most detailed embryological studies are those of Manton (1928) on Hemimysis lamornae (Couch), Wagner (1896) and Needham (1937) on Neomysis integer (Leach), and Nair (1939) on the tropical species Mesopodopsis orientalis (W. M. Tattersall). Kinne (1955) describes and figures the general body forms of the different stages of development of the larvae in the marsupium of Neomysis integer; Vannini (1930) examines the larvae of Leptomysis lingvura (G. O. Sars), while Kane (1904) illustrates the most advanced larval stage of Mysis relicta Lovén. The larvae of several non-British species have been described -Boreomysis arctica (Kröyer) by Jepsen (1965), Mysidium columbiae (Zimmer) by Davis (1966) and Neomysis intermedia Czerniavsky by Murano (1964b).

Many studies have been made on the metabolism of polycyclic aromatic hydrocarbons in mammals and it has been shown that these animals can convert compounds such as naphthalene into several metabolites (see, for example, Corner & Young, 1955). Baldwin (1957) has remarked on the ability of mammals to metabolize substances that they are unlikely to meet ‘except through the medium of the laboratory’. Marine animals, how-ever, can encounter these compounds in their normal environment, considerable quantities of polycyclic aromatic hydrocarbons being present in crude oil (Boylan & Tripp, 1971), in which form substantial amounts must be released into the sea annually.

Little work has been done on the metabolism of naphthalene in marine animals, apart from studies confined – as far as we are aware – to experiments with three species of fish (Lee, Sauerheber & Dobbs, 1972) and the mussel Mytilus edulis L. (Lee, Sauerheber & Benson, 1972). Data obtained using fish were consistent with those of earlier studies with mammals in showing that the hydrocarbon is converted into hydroxylated derivatives: but no evidence of naphthalene metabolism was found in the experiments with Mytilus. Indeed, until the present work, the only species of invertebrate that has been found to metabolize the compound is the housefly Musca domestica L. (Terriere, Boose & Roubal, 1961).

The present study, using Maia squinado (Herbst), has been carried out as part of a general investigation of the accumulation of polycyclic aromatic hydrocarbons in marine food chains and was designed to establish whether a marine crustacean possesses a means of metabolizing naphthalene by converting it into soluble excretion products.

A micro-analytical scheme for the determination of protein, carbohydrate, lipid and RNA levels in marine invertebrate larvae has been described in a previous paper (Holland & Gabbott, 1971). This addendum describes minor modifications to the scheme so that the level of DNA may be determined and includes a different procedure for the determination of RNA by u.v. absorption. DNA and RNA levels were determined in a number of nauplii and veliger larvae.

In the first paper of this series (Bryan & Hummerstone, 1971) it was shown that in the estuarine polychaete Nereis diversicolor O. F. Müller the concentration of copper is roughly proportional to that of the surrounding sediment. On the other hand, concentrations of zinc appeared to be relatively independent of those in the sediment and it was suggested that the level of zinc in the worm is regulated.

In a previous paper (Bryan & Hummerstone, 1971) the average concentrations of copper, zinc, lead, manganese and iron in the polychaete Nereis diversicolor O. F. Müller from several estuaries draining the mineralized areas of South-West England were compared with concentrations in the sediments. Although high levels of copper and zinc were encountered in some sediments none contained high levels of manganese and, in the worms, concentrations of manganese were low and relatively constant. Other estuaries in the area have since been examined, but although thousands of μg/g of copper, zinc, lead and arsenic have been found in some sediments, concentrations of manganese exceeding 1000, μg/g have rarely been encountered. Manganese ores occur quite widely in South-West England but the scale of mining appears to have been small by comparison with that for more obvious contaminants of estuaries such as copper, lead and arsenic (Dines, 1956). However, it is thought that the field observations and experimental results described in this paper can be extrapolated to situations where much higher concentrations of manganese occur.

Salps swim by rhythmic contraction of the hoop-like bands of muscle which form a series of incomplete annuli along the body. The histology of these muscle bands was briefly examined by various early workers, such as Dolley (1887) and Knoll (1895), but was little known until Fedele (1932,1938) published the results of his careful investigations of a variety of species. His observations demonstrated the complexity and peculiarity of the muscle fibres forming the bands, which, as he pointed out, are in some respects comparable to those of arthropods in the arrangement of the sarcomeres. In all the species he examined, Fedele found that the muscle fibres were essentially similar in organization: a central granular core containing large nuclei was surrounded on the free borders of the fibre by a layer of myofibrils. However, this general arrangement differed in detail between different species, and Fedele recognized five types of muscle fibre, distinguishing these types upon such criteria as the fibrillar arrangement, and the disposition of the nuclei. In an earlier paper (Fedele, 1925) he had also given very clear figures of the manner in which these muscle fibres were innervated. He found that dis-crete motor end-formations occurred on the surface of the muscle bands, and that these were frequently intercalary, unlike the motor terminations of vertebrates.

Fedele's work was based upon very careful observation of living and fixed material at the light microscope level; in the present note, we extend his observations by describing the ultrastructure of these curious protochordate muscle fibres.

All animals do not display the same capacities for repairing injuries, i.e. they possess what may be termed different ‘regeneration potentials’. One parameter influencing the regeneration potential manifested by an organism is its developmental history, or ontogeny. Early in an animal's ontogeny many of its cells are still undergoing both structural and biochemical modifications. As the animal matures, its cells become increasingly differentiated, ultimately attaining a high degree of specialization (Hay, 1966; Balinsky, 1970).

Numerous studies support the contention that the younger an animal ontogenically, the greater is its regeneration potential. Investigations using amphibians have presented several cogent examples of this generalization (Balinsky, 1970). Analogous situations are also evident in the Cnidaria. In the hydrozoan, Hydra, the tentacles contain what are among the ontogenically ‘oldest’ cells in the organism (Tripp, 1928; Brien & Reniers-Decoen, 1949; Burnett, 1966; Campbell, 1967b). Unlike the remainder of the organism, these structures also reportedly possess no regeneration potential (Peebles, 1897; Kanaev, 1952).

Three explanations have been proposed to account for the absence of regeneration potential in isolated tentacles. Nussbaum (cited in Kanaev, 1952) suggested that the absence of interstitial cells in the tentacles precluded regeneration. However, other regions of the animal, when experimentally deprived of this cell type, retained their regenerative capacities (Brien, 1953; Diehl & Burnett, 1964).

A second explanation invoked the size of an isolated tentacle as a factor limiting regeneration. In disputing this suggestion, Peebles (1897) measured tentacle volume. Isolated Hydra grisea (Pallas) tentacles ranged from 0.01 to to 0.03 mm3, while the volume of the smallest body fragment capable of total regeneration was considerably smaller, 0.006 to 0.01 mm3. From these measurements she concluded that the size of isolated tentacles could not account for the inability to regenerate.

Many workers have experienced difficulties in trying to identify species within the genus Enteromorpha. The difficulties arise from our lack of knowledge of the range of variation for the characters used to delimit the taxa and of the sources of the variation shown.

Enteromorpha intestinalis (L.) Link was originally described by Linnaeus (1753) under the name Ulva intestinalis as ‘Ulva tubulosa simplex’ and Enteromorpha compressa (L.) Grev., also by Linnaeus (1753) under the name Ulva compressa as ‘Ulva tubulosa ramosa compressa’. In their interpretations by later authors, the two species differ only in that the former is unbranched and the latter branched. In their cell size, in the unordered arrangement of the cells and in the single pyrenoid in the chloroplast, they seem to belong together. Whether or not a plant is branched would seem to be a straightforward character to use in practice, but for an alga of this kind this is not necessarily so. In its development the unbranched tube of the thallus begins life as a zoospore or zygote which at first divides transversely to form a short uniseriate filament and later by radial longitudinal divisions, the subsequent expansion of which leads to the formation of the hollow tube. In the formation of branches, individual cells, usually towards the base of the frond, divide by a single periclinal division. The outer cell of the pair thus formed then divides transversely forming a single-celled filament, later dividing by radial longitudinal divisions and repeating the structure of the main axis.

The type species of Platychrysis, P. pigra, was described by Geitler in 1930 from a sample taken at Las Palmas in the Canary Islands (Geitler, 1930). It was later recorded by Carter in 1937 from a brackish pool at Bembridge, Isle of Wight, and a more complete description of the species was given, including a description of the motile cells (Carter, 1937). A taxonomic comparison of the three genera Prymnesium J. Massart, Chrysochromulina Lackey and Platychrysis Geitler was published by Conrad (1941), whose Belgian records for the species (Lilloo) were subsequently published in 1954 (Conrad & Kufferath, 1954). In 1967, Norris (Norris, 1967) described a new species, P. neustophila, recorded from Puerto Peñasco (Mexico), but this species needs further investigation since the account is somewhat incomplete.

A number of workers have studied the uptake of zinc by algae, but the mechanisms of uptake are not fully understood. Broda, Desser & Findennegg (1964) concluded that 65Zn uptake by Chlorella was a passive process since it was affected neither by metabolic inhibitors nor by anaerobic conditions. In later papers, however, Broda and co-workers (Matzku & Broda, 1970; Findennegg, Paschinger & Broda, 1971) have concluded that 65Zn uptake occurs both by a rapid passive process of ion-exchange and also by a slower, metabolically dependent process. Bachmann & Odum (1960) showed that65Zn uptake by Chaetomorpha was stimulated by light and they concluded that uptake was a metabolically active process. Gutknecht (1961,1963) showed that uptake of65Zn by Viva and Porphyra was stimulated by illumination and by increase in temperature. He also showed that increase in pH of the surrounding medium increased65Zn uptake and thus concluded that65Zn uptake was a passive process which was affected indirectly by metabolism.

At the present time only limited data about the release of organic matter by phyto-plankton in the marine environment are available (Antia, McAllister, Parsons, Stephens & Strickland, 1963; Fogg, Nalewajko & Watt, 1965; Hellebust, 1967; Jitts, 1967; Home, Fogg & Eagle, 1969; Anderson & Zeutschel, 1970; Thomas, 1971; Samuel, Shah & Fogg, 1971).

A few studies on the excretion of organic matter by marine phytoplankton in culture have been reported (Guillard & Wangersky, 1958; Wangersky & Guillard, 1960; Stewart, 1963; Hellebust, 1965). Eppley & Sloan (1965) reported extensive excretion in Skeletonema costatum (Greville) Cleve cultures as they approached senescence and emphasized that excretion is inversely proportional to the physiological activity of cells. Hellebust (1965) demonstrated the release of high amounts (up to 38% of the carbon assimilated) of organic matter by Sk. costatum cells exposed to low light intensities. It is apparent that more knowledge is needed in order to define the intra- and extracellular factors affecting the excretion.

It has been suggested in Part IV of these contributions that the larger diameter of centric diatom cells met with in collections made in the oceans in the lower latitudes might be caused in part by the relatively greater grazing known to take place in these areas (Steemann-Nielsen, 1962; Lohmann, 1912). Eight series of experiments were therefore carried out to determine any effect that might be attributed to animals grazing on populations of centric marine diatoms.

In spite of the large number of Chlamydomonas species which have been described, there is very little information on those occurring in marine or brackish environments. Many of the earlier descriptions may be disregarded as being not sufficiently complete for recognition (e.g. Schiller, 1913, 19255 West, 1916; Wille, 1903), whilst in recent years only a few marine species have been observed and studied in detail (Chadefaud, 1951; Dangeard, 1965; Ettl, 1967).