Structure and function of the eversible organs of several genera of larval firefly (Coleoptera: Lampyridae)

Larval defensive behaviour and eversible organ morphology were compared in the firefly species Luciola cruciata Motschulsky 1854, L. lateralis Motschulsky 1860, L. leii Fu et Ballantyne 2006, Lampyris noctiluca Linnaeus 1767, Pyrocoelia analis Fabricius 1801, P. pectoralis Oliver 1883, P. sp. and two Diaphanes species. In all cases the eversible organs are located on the pleural cuticle, dorsal to the spiracle, but there is considerable variation between species in their number, size and shape. In La. noctiluca they are confined to the abdomen, whereas in the other species they also occur on the meta- and mesothorax. In La. noctiluca and the Pyrocoelia species the organs are columnar in shape, contrasting with the forked organs of the Luciola and Diaphanes species. The eversible organs of the Luciola species, which are all aquatic, are remarkably larger (relative to body length) than those of the other, terrestrial species. On organ eversion the Luciola species emit an odour resembling pine oil, the Diaphanes species smell weakly of mint and L. noctiluca and the Pyrocoelia species produce no discernible scent, though ants are nonetheless repelled by contact with everted L. noctiluca organs. The organs of all the species studied support protuberances on their external surface, though these too vary in shape, size and ornamentation between species. In all species except L. noctiluca each protuberance is connected to a well-developed globular body via a long, thick stalk. Circular foveae are located in the centres of these globular bodies. The globular bodies consist of secretory cells characterized by the presence of numerous mitochondria and an extensive system of cisternae and tubular endoplasmic reticulum. Behavioural tests revealed that small larvae run away instead of becoming immobile and glowing, whereas large larvae start to glow when disturbed. The study shows that the eversible larval organs form an important part of a defensive arsenal in the Lampyridae.     

Comparative morphology and cytology of siphons and siphonal sensory organs in selected bivalve molluscs

 The form, anatomy and cytology of the water-passages in siphon-possessing and siphon-lacking species of a selected group of bivalve molluscs from the Red Sea (Callista florida, Circe currogata, C. crocea, Lucinia dentifera, Dosinia histrio, Pitar hebraea, Tridacna maxima, Pteria aegyptica), and from the Mediterranean Sea (Spondylus spinosus, Pinctada radiata, Pinna nobilis, Donax trunculus, D. semistriatus, Mactra stultorum, Tapes decussatus, Petricola lithophaga, Brachidontes pharaonis) were studied by means of light and electron microscopy. In the mytiloids, ostreoids and ptrioids studied, the water-passages are covered by a ciliated epithelium and the few tentacles around their openings are identical to those found on the mantle edges. Contrary to this, in the veneroids studied, the siphons are covered by a microvillar epithelium and their tentacles, especially of the inhalant siphon, reveal characteristic branching. The so-called Type I, Type II and Type III ciliated sensory organs on and within the siphons are similar to those observed in other bivalves, differing from each other in the dimension, number and form of cilia. In the studied mytiloid species only Type I and Type II organs were found. The form and structure of the siphons and the distribution of sensors on them can be used as markers for ecological as well as phylogenetic considerations. Received: 28 January 2000 / Accepted: 28 May 2000     

Ecology of two littoral species of caprellid amphipods (Crustacea) from Washington,USA

Ecology of 2 littoral species of caprellid amphipods is compared. Populations of Caprella laeviuscula, a periphyton scraper/filter-feeder, are most dense on eelgrass Zostera marina L. In the absence of C. laeviuscula, periphyton biomass increases 411% in protected Z. marina beds. The light absorption spectra of periphyton and Z. marina are similar, and C. laeviuscula, by its periphyton removal, may allow Z. marina to grow in areas where it would otherwise be excluded. C. laeviuscula is aggressively dominant over sympatric caprellids, and seasonal predators of C. laeviuscula are absent during winter, the period when periphyton would be most limiting to Z. marina. Populations of Deutella californica, a predator, are most dense on the hydroid Obelia dichotoma (L.). In the O. dichotoma epibiotic community, D. californica is the primary predator, but removal did not change the composition of the community structure. In the absence of other macropredators, the structure of the O. dichotoma epibiotic community depends more on the seasonality of O. dichotoma occurrence than on organismal interactions.     

Range extensions of teredinids (shipworms) and polychaetes in the vicinity of a temperate-zone nuclear generating station

A study of marine boring and fouling organisms in the vicinity of the thermal effluent from the Oyster Creek Nuclear Generating Station, Barnegat Bay, New Jersey, USA has been conducted since 1971. Two subtropical species of shipworms have been found in significant numbers in the effluent. These are Teredo bartschi Clapp and Teredo furcifera von Martens. The shipworm Lyrodus sp. and the flatworm Taenioplana teredini Hyman, which is predatory on teredinids, were also found, but on only one occasion. The polychaete Ficopomatus enigmaticus (Fauvel) has been found for the first time on the Atlantic Coast of North America. Three other polychaetes, Potamilla (Potamethus) spathiferus (Ehlers), Loimia medusa (Savigny), and Sphaerosyllis sp., have been newly identified from Barnegat Bay, but probably are not recent range extensions. Only T. bartschi, T. furcifera, and F. enigmaticus have established breeding populations. Their distributions and abundances are probably related to the thermal effluent; this is most clear in the case of T. bartschi and least clear in the case of F. enigmaticus. T. bartschi was confined at first to the heated effluent in Oyster Creek, but has spread to Forked River. It has become a major faunal element in Oyster Creek. The impact of the other exotic species has been negligible. The primary mechanism of the range extensions is by boat transport.     

Mechanistic aspects of the thermal formation of halogenated organic compounds including polychlorinated dibenzo‐p‐dioxins. Part V†: Hypotheses and summary

The hypotheses on the de novo syntheses of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo‐p‐dioxins (PCDDs), based on known literature, are presented. Polychlorinated benzenes and polychlorinated phenols are probably key intermediates.

In the present article, hypotheses that may account for the presence of polychlorinated dibenzofurans (PCDFs) and dibenzo‐p‐dioxins (PCDDs) in the effluents from municipal and industrial incinerators are put forward. These hypotheses are based on the previously surveyed literature (Ref. 203–206) and experimental results on laboratory scale and thermodynamic calculations are considered. The interconnections of various reaction steps are speculative and no technological information was added to account for conditions in real incinerators. Conclusion of the discussions on the related subject matter, presented in the Parts I‐IV (Ref. 203–206), are also described in this paper.     

Behavior and ecology of Old World Luperini beetles of the genusAulacophora (Coleoptera: Chrysomelidae)

Summary The attraction of Old World leaf beetles in the genusAulacophora to kairomones and parakairomones which are effective lures for New WorldDiabrotica andAcalymma were investigated. Beetles captured on sticky traps baited with single and multicomponent lures were no different from the control traps for two species ofAulacophora. Yellow colored traps and squash blossoms are attractive toAulacophora beetles which detect sub-microgram quantities of cucurbitacins on silica gel. Leaf feeding behavior and flight activity data are correlated with varietal preference of threeAulacophora species. The common response byDiabrotica andAulacophora to cucurbitacins reinforces the two groups' coevolutionary association with the Cucurbitaceae. The apparent lack of a common response toCucurbita blossom volatiles suggests recent evolutionary pathways are substantially different for these two groups of beetles.     

Morphological and habitat divergence in the intertidal limpet Patelloida pygmaea

In the intertidal limpet Patelloida pygmaea, two distinctive morphs, the forms pygmaea and conulus, have been recorded. The former possesses a flat elongated shell, and the latter has an extremely high round shell. It has been observed in the field that pygmaea is found on oyster shells Crassostrea gigas. The form conulus uses an unusual substrate for attachment. It is found on the living shells of the intertidal gastropod Batillaria cumingi. Although conulus is normally found only on shells of Batillaria, it can also be found on oyster shells when pygmaea and Batillaria shells are not present in nature. An electrophoretic analysis of allozymes showed that these two forms are reproductively isolated from each other and coexist without gene exchange on the same mudflat. Laboratory experiments showed that pygmaea prefers oyster shells and conulus prefers Batillaria shells as substrates for attachment when both oyster and Batillaria shells are present. The form pygmaea did not attach to Batillaria shells, even when only Batillaria shells were available. However, conulus also attached to oyster shells when Batillaria shells were not available. The proportion of individuals of conulus that attached to oyster shells decreased significantly when pygmaea was attaching to the oyster shells. These results suggest that pygmaea is ecologically more specialized to living on oyster shells than conulus.     

Macroalgae as habitat patch islands for Scutellidium lamellipes (Copepoda: Harpacticoida) and Ampithoe tea (Amphipoda: Gammaridae)

Scutellidium lamellipes and Ampithoe tea live in patches formed by the brown alga Pelvetia fastigiata. The distributions and abundance of both crustaceans were examined on P. fastigiata obtained during 1975 and 1976 from 7 collecting and 6 experimental sites in the mid-intertidal zone at La Jolla, California (USA). At each collecting site, the abundance of each crustacean generally increases with increasing plant size. Following defaunation and transplantation of algae, abundances of both crustaceans on individual plants appear to be governed by equilibria determined by in situ reproduction, immigration and emigration. Immigration rates of both animal species decrease significantly with increasing distance from areas occupied by P. fastigiata. During short-term experiments, neither crustacean was able to establish colonies on defaunated plants placed across a 30 m P. fastigiata-free zone and both species would have to reproduce to persitst on plants transplanted to that site. More frequent immigration and reproduction (and, for S. lamellipes at least, decreasing emigration rates with increasing patch size) would increase abundances and decrease probabilities of local extinction on larger and/or less distant plants. However, even within sites with isolated plants, the smallest plants often are not inhabited by either crustacean. The densitics of both species differ with plant size and distribution. Densities of S. lamellipes are greatest within a large aggregation of P. fastigiata, whereas those of A. tea are greatest on moderate-sized isolated plants at mid-tide levels.     

Biology and ecology of the crab Rhithropanopeus harrisii ssp. tridentatus

Data are presented on the geographic and local distributions as well as on the life cycle of the crab Rhithropanopeus harrisii (Gould) ssp. tridentatus (Maitland). Extensive studies on this subspecies were carried out in its natural habitat (an abandoned arm of the Vistula, Poland), and under laboratory conditions. The effects of some environmental factors on distribution, life cycles, and abundance of the crab are discussed. The results obtained are compared with those reported by other investigators.     

Defenses and refuges: alternative mechanisms of coexistence between a predatory gastropod and its ascidian prey

Only five of the 14 species of solitary ascidians in the San Juan Islands, Washington, USA commonly co-occur with an abundant predator of the rocky subtidal, the gastropod Fusitriton oregonensis. None of the common subtidal species is defended by vanadium or sulfuric acid; concentrations of these substances are highest in species that are eaten readily by F. oregonensis and are uncommon in the rocky subtidal. Experimental manipulations indicate that Halocynthia igaboja are protected by stiff spines of the tunic. The defense mechanism of Pyura haustor consists of a tough, leathery tunic with inorganic inclusions, and microscopic spines around the siphons. Boltenia villosa and Styela gibbsii are eaten by snails in the laboratory, but live in areas where the predator is abundant. Both find refuge as epizooites on P. haustor and H. igaboja. The mechanisms by which Cnemidocarpa finmarkiensis persists in the presence of F. oregonensis is unknown.     

Bioaccumulation of platinum group metals on some fish species ( Oreochromis niloticus,Penaeus laspisulcates,Scylla serrate,Galaxias brevipinnis and Mollusc ) in the Pra estuary of Ghana

Catalytic converters have been designed to solve the problem of pollution from automobiles. However, recent studies have shown that the platinum group metals (PGMs) that are used in the design are being deposited alongside highways. The objective of this study was to measure the levels of PGMs that bioaccumulate in Oreochromis niloticus, Penaeus laspisulcates, Scylla serrate, Galaxias brevipinnis and Mollusc in the river Pra estuary along a major highway in Ghana. Chemical analysis using neutron activation analysis showed accumulation of the PGMs in all the biota species analysed. The S. serrate and mollusc showed higher accumulation than the other species. The mollusc and the other fish species in the estuary are consumed in Ghana, and therefore there is the need to educate the population on the effect of the PGMs on their health.     

Patterns of use of space in a guild of territorial reef fishes

There exists on Heron Reef, at the southern end of the Great Barrier Reef, an 8-species guild of ecologically very similar, territorial, herbivorous reef fishes. All individuals of these species maintain territories on rubble substrata throughout juvenile and adult life. Territories are defended from all other guild members. Three rubble patches, each containing residents of 3 guild species: Pomacentrus apicalis, P. wardi, and Abudafduf lachrymatus, have been monitored for 12 to 18 months. This paper examines the patterns of use of space as shown by the antecedent and subsequent histories of sites chosen by 43 new colonists, and sites vacated through the loss of 34 residents on the rubble patches. In addition, variation through time is examined in the total amount of space held in territories on each rubble patch. The 3 species show similar preferences for space as colonists, although adult and juvenile colonists behave differently. Numbers of colonists detected on rubble patches are not proportional to the resident populations of the 3 species. Residents of the 3 species are equal in their abilities to enter spaces vacated through mortality, although they differ slightly in methods used to enter sites. They do not respond preferentially to sites previously occupied by any particular species. P. wardi shows a higher rate of mortality than the other species, and residents of this species are more often dislodged by new colonists. The total amount of space held on any rubble patch did not vary during the year from September, 1972 to October, 1973. The data are interpreted as supporting the hypothesis that the 3 species do not differ in their requirements for space on rubble patches, and that they are in competition for a short supply of such space. Differences exist in their strategies for obtaining and holding such space. These differences are important for explaining the continued presence of P. wardi on rubble patches. P. apicalis and a. lachrymatus are both specialists in holding territories on the upper reef slope. No differences have been detected in their requirements or competitive abilities. P. wardi is a fugitive species on the upper reef slope, coexisting because it maintains a refuge from competition by occupying some un-preferred sites off rubble patches.     

Changes in barnacle population structure along an intertidal community gradient in the Florida Keys

Population distributions, densities and percentage deaths and individual size variations of the barnacles Chthamalus stellatus and Tetraclita squamosa, and the distribution of the vermetid snail Spirogluphus annulatus are measured to clarify determinants the Florida Keys (USA). The species composition of the pilings community and barnacle population densities correspond to physical gradients dependent on piling distance from shore. Interspecific competition for space is insignificant in determining C. stellatus presence or absence on pilings. Intraspecific crowding in highdensity zones of adult T. squamosa is evidenced by a significant decrease in basal diameter as density increases. The peak percentage of dead C. stellatus coincides with peak densities. The percentage of dead T. squamosa is at a low point at peak densities due to the ability of T. squamosa cyprids to settle and survive on adult shells in high-density regions. Feasible perturbation experiments for testing the importance of interspecific competition in determining the densities and vertical distributions of the species are discussed. The results of such experiments can be used to test the assumptions and predictions of the widely applied competition coefficient measure proposed by Levins (1968). Several theoretical deficiencies of Levins' measure are discussed.     

Defensive secretions from the larvae ofApatania fimbriata (Pictet) (Trichoptera: Limnephilidae)

Summary When the larvae of the caddis flyApatania fimbriata (Pictet) are threatened, drops of fluid appear on their head capsules. The secretions are produced in a gland in the dorsal part of the prothorax. The neck region contains an eversible sac with numerous single setae, groups of 3 setae, or rows of setae on the surface. The secretion is released through two paris of orifices on the lateral sides of the sac. For the most part the secretion is composed of some 30 fatty acids, with the major components having 12–14 carbon atoms and up to 4 double bonds (approx. 1–2 µg secretion per specimen). Biotests with synthetic saturated acids (C₆–C₁₂) in a stream and in the laboratory demonstrated a paralysing effect on small invertebrate predators (Rhyacophila sp.,Plectrocnemia conspersa, Hydropsyche sp., larvae, all Trichoptera). In choice experiments,Rhyacophila sp. larvae preferred larvae ofAgapetus fuscipes andDrusus annulatus (Trichoptera) as food as compared withApatania fimbriata larvae. Larger predators, such asDinocras cephalotes (Insecta, Plecoptera) and the fishCottus gobio, did not discriminate betweenApatania fimbriata and other prey species. The use of fatty acids in defensive secretions is interpreted as an adaptation to the running water environment. They are effective repellents againstRhyacophila sp. larvae, the most important predator in the natural environment ofApatania larvae.     

Introduced versus native subspecies of Codium fragile: how distinctive is the invasive subspecies tomentosoides?

After its introduction, the green alga Codium fragile (Sur.) Hariot ssp. tomentosoides (van Goor) Silva has spread widely on several temperate-zone, rocky shores where non-weedy conspecific subspecies occur (N.E. Atlantic, N.E. Pacific, S. Pacific). To determine how phenologically and morphologically distinctive the invasive alga was relative to native subspecies, I compared marine intertidal populations of C. fragile ssp. tomentosoides and the native C. fragile ssp. novaezelandiae (J. Ag.) Silva (hereafter referred to as ssp. tomentosoides and ssp. novae-zelandiae respectively on New Zealand shores in 1992, 1993 and 1995. On the North Island, the invasive ssp. tomentosoides is sparsely distributed on low intertidal benches on wave-protected shores in the Hauraki Gulf (east coast) in spring and summer, and thalli die back to the perennial holdfast in autumn. In contrast, the native ssp. novaezelandiae forms dense beds within the low intertidal mussel zone on wave-swept shores of Maori Bay (west coast), and fronds are perennial. Whereas ssp. tomentosoides has only a few fronds arising from the spongy basal hold-fast, ssp. novae-zelandiae thalli are composed of many fronds. The ssp. tomentosoides from the Hauraki Gulf is significantly more branched than comparably sized native conspecifics from Maori Bay. These phenological and morphological differences were used to predict the subspecific identity of C. fragile from three other locations on the North Island, two locations on the South Island, and four locations on S.E. Australian shores; microscopic examination of utricles was used to check the predictions. Seasonality and number of fronds per thallus are the most reliable characters for field identification of native vs invasive subspecies: perennial intertidal thalli with large numbers of fronds are indicative of native subspecies for different geographic regions.     

Not all ctenophores are hermaphrodites. Studies on the systematics,distribution, sexuality and development of two species of Ocyropsis

The lobate ctenophores Ocyropsis maculata and O. crystallina are not simultaneous hermaphrodites, based on morphological, histological and experimental evidence. Sex ratios in populations, sex ratios of size classes within populations, and average sizes of males and females support the hypothesis that both species are dioecious, rather than sequential hermaphrodites. We have divided each species into two subspecies, based on morphology and geographic distribution. Preliminary evidence suggests that the subspecies also differ in reproductive behavior. One subspecies, O. crystallina guttata, spawns on a daily cycle in the laboratory, and spawning becomes more synchronous when males and females are placed together. Species of Ocyropsis, all of which are oceanic in distribution, are probably descended from a common ancestor that was a simultaneous hermaphrodite. That this group of oceanic ctenophores evolved dioecy directly contradicts the assertion that there is a selective advantage to hermaphroditism in environments where the probability of finding a mate is reduced.     

Sympatry in grapsoid crabs (genera <Emphasis Type="Italic">Planes</Emphasis> and <Emphasis Type="Italic">Plagusia</Emphasis>) from olive ridley sea turtles (<Emphasis Type="Italic">Lepidochelys olivacea</Emphasis>), with descriptions of crab diets and masticatory structures

Grapsoid crabs of the genera Planes and Plagusia are commonly referred to as “rafting crabs” due to their propensity to live on flotsam and pelagic marine animals. Planes minutus and Planes major (=Planes cyaneus) are epibionts of sea turtles. Occurrences of grapsoid crabs in the genera Planes and Plagusia were evaluated on a total of 27 olive ridley sea turtles, Lepidochelys olivacea, from the eastern tropic Pacific (1998–2001) and the Hawaiian Islands (2002) captured in July–December each year. This is the first report of Planes marinus and Plagusia squamosa on sea turtles, and of P. major, P. marinus, and P. squamosa in sympatry on a confined substrate. Stomach content analyses showed P. major and P. marinus consumed a variety of neuston and marine vegetation, with the former consuming considerably more animal material. Epibiotic P. squamosa consumed mostly plant material. The three Planes species had distinctive differences in gastric mill tooth morphology. The versatile mouthparts of P. marinus are described and resemble those of their congeners. Most female P. major and P. marinus collected were ovigerous and present in all survey months.     

Two herbivore-deterrent iridoid glycosides reduce the in-vitro growth of a specialist but not of a generalist pathogenic fungus of Plantago lanceolata L

Summary. Many secondary plant compounds are involved in defense against both insect herbivores and pathogens. Two secondary plant compounds of Plantago lanceolata, the iridoid glycosides catalpol and its precursor aucubin, are well known for their deterrent effects on generalist and non-adapted specialist insect herbivores. We tested the effects of these compounds on the in-vitro growth of a specialist and generalist fungal pathogen of this host species. Two chemical forms of these iridoids were tested. The glycosides and their aglycones, the products of enzymatic conversion by specific $/Beta$-glucosidase enzymes. The glycosides enhanced growth of both the specialist fungus Diaporthe adunca and the generalist fungus Fusarium moniliforme var. subglutinans. The positive effect of these glycosides on the generalist fungus is in sharp contrast with the generally negative effects of these glysosides on generalist insect herbivores. The aglycones of aucubin and catalpol reduced the growth of the specialist fungus D. adunca, but, contrary to expectation, enhanced the growth of the generalist fungus F. moniliforme var. subglutinans. Effects of aucubin on D. adunca were stronger than effects of catalpol. This was true both for the growth stimulating effects of the glycosides and for the fungitoxic effects of the aglycones. We therefore expect that the effects of these iridoids in P. lanceolata on the specialist fungus will strongly depend on the ratio between catalpol and its precursor aucubin and the chemical form (glycoside or aglycone) in which these compounds are encountered by the fungus during growth. Our results suggest that iridoid glycosides in P. lanceolata can be used as defense against both herbivores and pathogens, but that their effects are highly specific with respect to the natural enemy species that is encountered. Received 11 April 2002; accepted 9 August 2002     

Purification of multiple vitellogenins in grey mullet (<Emphasis Type="Italic">Mugil cephalus</Emphasis>)

Coralliophila abbreviata (Lamarck) is a corallivorous gastropod that lives and feeds on several species of scleractinian coral in the Western Atlantic and Caribbean. Previous studies of C. abbreviata have revealed that snails on branching acroporid corals are larger and consume more tissue than those on massive and plating corals. To ascertain whether snail life-history and fitness are differentially affected by the coral host, an analysis of the age structure and female reproductive output of snail populations on three coral host taxa (Acropora palmata, Diploria spp., and Montastraea spp.) was conducted at four shallow (2–7 m depth) reef sites off Key Largo, Florida in June through August, 2004. Snails were, on average, almost twice as large on A. palmata than on Diploria spp. and Montastraea spp., averaging 30.3 mm shell length, compared to 17.2 and 17.6 mm, respectively. Brood size increased as a power function with female shell length. Females on A. palmata were significantly larger than females on the other two hosts and, therefore, produced more offspring per female. The number of growth striae on the inner surface of the operculum was used to estimate snail age. Estimates of growth rate were obtained by fitting the Gompertz growth function to size-at-age plots and mortality was estimated using growth parameters and size-frequency data. The data suggest that C. abbreviata inhabiting A. palmata are larger than on alternative hosts due to a combination of a faster growth rate and longer life-span. The species is believed to be a protandrous hermaphrodite. The timing of sex change varied among hosts; snails on A. palmata changed sex later at larger sizes relative to those on the other two hosts. Based on these results, it seems probable that C. abbreviata has developed reaction norms for life-history traits, allowing snails to adjust and maximize fitness in the different environments associated with various coral hosts.     

Diets of some deep-sea brittle stars in the Rockall Trough

The stomachs of 1 165 individuals of the species Ophiacantha bidentata (Retzius), Ophiactis abyssicola (M. Sars), Ophiocten gracilis (O. Sars), Ophiura irrorata (Lyman), O. ljungmani (Lyman) and Ophiomusium lymani Wyville Thomson, collected from the general area of the Rockall Trough from 1973 to 1983, were examined; 47% contained material. This varied in nature and in volume between individuals, but overall, the diets of the 6 species showed quite high similarity. The few differences evident are interpreted as reflecting different lifestyles. Except for Ophiocten gracilis, the probably motile, epifaunal species (Ophiura irrorata, O. ljungmani and Ophiomusium lymani) showed the greatest variety in items, and the lowest similarity with the remaining species; they are probably unselective omnivores, eating whatever small prey or organic detritus they are able to find. Ophiacantha bidentata and Ophiactis abyssicola showed both the least dietary variety, and the highest similarity to each other. This probably reflects their more sedentary lifestyle, feeding on current-borne particles and small prey from perches on sessile fauna. The stomach contents of Ophiocten gracilis consisted mainly of amorphous organic material and mineral particles, indicating a microphagous feeding mechanism. With O. gracilis, the proportion of stomachs with food decreased markedly in summer, this coinciding with seasonal gonadal development when stomachs frequently appeared ruptured or compressed. The possible importance of seasonal sedimentation of fast-sinking particulates from the surface is discussed in relation to finds of flocculent organic material, often containing diatom frustules, in stomachs of all 6 species. Some doubts remain as to whether our results are biased by specimens egesting stomach contents on capture. As in shallow water, deep-sea ophiuroids seem to be trophic generalists lacking in dietary specialization. Brief notes on parasites encountered are also given.