Feeding Biology Research Articles

Qualitative assessment of the diet of European eel larvae in the Sargasso Sea resolved by DNA barcoding

European eels (Anguilla anguilla) undertake spawning migrations of more than 5000 km from continental Europe and North Africa to frontal zones in the Sargasso Sea. Subsequently, the larval offspring are advected by large-scale eastward ocean currents towards continental waters. However, the Sargasso Sea is oligotrophic, with generally low plankton biomass, and the feeding biology of eel larvae has so far remained a mystery, hampering understanding of this peculiar life history. DNA barcoding of gut contents of 61 genetically identified A. anguilla larvae caught in the Sargasso Sea showed that even the smallest larvae feed on a striking variety of plankton organisms, and that gelatinous zooplankton is of fundamental dietary importance. Hence, the specific plankton composition seems essential for eel larval feeding and growth, suggesting a linkage between eel survival and regional plankton productivity. These novel insights into the prey of Atlantic eels may furthermore facilitate eel larval rearing in aquaculture, which ultimately may replace the unsustainable use of wild-caught glass eels.

Habitat Utilization and Feeding Biology of Himalayan Grey Langur (<I>Semnopithecus entellus ajex</I>) in Machiara National Park, Azad Jammu and Kashmir, Pakistan

Habitat utilization and feeding biology of Himalayan Grey Langur (Semnopithecus entellus ajex) were studied from April, 2006 to April, 2007 in Machiara National Park, Azad Jammu and Kashmir, Pakistan. The results showed that in the winter season the most preferred habitat of the langurs was the moist temperate coniferous forests interspersed with deciduous trees, while in the summer season they preferred to migrate into the subalpine scrub forests at higher altitudes. Langurs were folivorous in feeding habit, recorded as consuming more than 49 plant species (27 in summer and 22 in winter) in the study area. The mature leaves (36.12%) were preferred over the young leaves (27.27%) while other food components comprised of fruits (17.00%), roots (9.45%), barks (6.69%), flowers (2.19%) and stems (1.28%) of various plant species.

Can Dental Microwear Textures Record Inter-Individual Dietary Variations?

BackgroundDental microwear analyses are commonly used to deduce the diet of extinct mammals. Conventional methods rely on the user identifying features within a 2D image. However, recent interdisciplinary research has lead to the development of an advanced methodology that is free of observer error, based on the automated quantification of 3D surfaces by combining confocal microscopy with scale-sensitive fractal analysis. This method has already proved to be very efficient in detecting dietary differences between species. Focusing on a finer, intra-specific scale of analysis, the aim of this study is to test this method's ability to track such differences between individuals from a single population.Methodology/Principal FindingsFor the purposes of this study, the 3D molar microwear of 78 individuals from a well-known population of extant roe deer (Capreolus caprelous) is quantified. Multivariate statistical analyses indicate significant seasonal and sexual differences in individual dental microwear design. These are probably the consequence of seasonal variations in fruit, seed and leaf availability, as well as differences in feeding preference between males and females due to distinct energy requirements during periods of rutting, gestation or giving birth. Nevertheless, further investigations using two-block Partial Least-Squares analysis show no strong relationship between individual stomach contents and microwear texture. This is an expected result, assuming that stomach contents are composed of food items ingested during the last few hours whereas dental microwear texture records the physical properties of items eaten over periods of days or weeks.Conclusions/SignificanceMicrowear 3D scale-sensitive fractal analysis does detect differences in diet ranging from the inter-feeding styles scale to the intra-population between-season and between-sex scales. It is therefore a possible tool, to be used with caution, in the further exploration of the feeding biology and ecology of extinct mammals.

Experimental infection of selected arthropods with spirurid nematodesSpirocerca lupiRailliet & Henry, 1911 andGongylonema ingluvicolaMolin, 1857

Gongylonema ingluvicola and Spirocerca lupi are spirurid nematodes that require arthropod intermediate hosts in order to complete their life cycle. Beetles of the family Scarabaeidae are reported to serve as intermediate hosts for both these parasites. In this study selected species of beetles of the family Scarabaeidae as well as other groups of arthropods were screened for susceptibility to infection with S. lupi and G. ingluvicola. Arthropods were exposed to infective eggs of both parasites for a determined period of time and dissected/digested to determine the presence or absence of pre-infective and infective larvae. All the five species of dung beetles exposed to infection with S. lupi, namely, Pachylomerus femoralis, Scarabaeus rugosus, Gymnopleurus humanus, Kheper nigroaeneus and Anachalcos convexus were susceptible and, of the two species exposed to G. ingluvicola, only Gy. humanus was susceptible. Spirocerca lupi eggs developed in millipede species, Daratoagonus cristulatus, and remained as encysted larvae, while in Orthoporoides kyrhocephalus no development was observed. Spirocerca lupi larvae were not detected in the cricket species Gryllus assimilis, or the cockroach species Periplaneta americana, and, similarly, G. ingluvicola larvae were not detected in the millipede species O. kyrhocephalus. The difference in the susceptibility of the arthropods to the two parasite species may depend on their feeding biology.

Predator–spreaders: Predation can enhance parasite success in a planktonic host–parasite system

The "healthy herds" hypothesis suggests that selective predators, by acting as parasite sinks, may inhibit the start of epidemics and reduce prevalence of infection. Here, we describe a counter-example using field patterns, experiments, and a model. The predator Chaoborus releases infective spores of a fungal parasite and, in doing so, may facilitate epidemics in Daphnia populations. In the field, epidemics occur in lakes with higher Chaoborus densities. Experiments revealed that nonselective Chaoborus release many of the spores contained in their prey. Since these released spores remain infective, this predator can catalyze epidemics when a lake's physical environment might otherwise impede them. Without Chaoborus, Daphnia dying of infection may sink to the lake bottom before releasing spores. A model tracking hosts and spores in the water column (where hosts contact spores) and in bottom sediments (where they cannot) illustrates this mechanism. Thus, by dispersing spores while feeding, this predator spreads disease. Many invertebrates are parasitized by obligately killing parasites, offering a variety of systems for additional tests of this "predator-spreader" hypothesis. In the meantime, this planktonic disease system prompts a very important, general warning: before we use predators to keep the herds healthy, we need to carefully think about the interface between predator feeding biology and the underlying epidemiology of wildlife disease.

Reproductive biology of Symphodus mediterraneus (Teleostei, Labridae) in the Azores

AbstractA description of the colour patterns, reproductive behaviour, spawning season and size at first maturity is given for an Atlantic population of Symphodus mediterraneus, based on underwater observations and animals collected by spear‐fishing and photographed. Gonad histology was used to determine the sex and maturity stages. Size at first maturation was estimated as the length at which 50% of the individuals are mature. General appearance was a brown or brownish‐red body, with a series of large brown transverse stripes, a conspicuous yellow‐ringed black spot on the base of the pectoral fins and a black spot on the caudal peduncle. Terminal males could be distinguished from females by the blue tones on the extremities of the median fins and on the throat. Differences from the colour pattern of the Mediterranean population are noted. This is probably a gonochoric species: the larger males are territorial, building algal nests and defending them from conspecific males and from other microbenthic carnivorous fishes; the smaller mature males did not show sneaking or satellite behaviour. Reproduction takes place in late spring and summer, after the spring productivity peak, suggesting that the feeding biology of the adults may be the main determinant factor of the timing of spawning. Total length at first maturity is 12.1 cm for males and 9.6 cm for females.

The AC–DC Correlation Monitor: New EPG design with flexible input resistors to detect both R and emf components for any piercing–sucking hemipteran

Much of what is known today about hemipteran feeding biology, as well as mechanisms of their host plant interactions and transmission of phytopathogens, has been learned via use of electrical penetration graph (EPG) technology, originally called electronic monitoring of insect feeding. Key to all of this information has been the electronic designs of EPG monitors. It has been 45 years since the publication of the original EPG, the AC monitor, and 30 years since introduction of the DC monitor, an important improvement for EPG science. Herein we describe our new AC–DC Correlation Monitor, the first major improvement in design since the DC monitor. We provide the monitor's block diagram and circuit description, and discuss (as a first example) its application to aphid feeding waveforms. Our instrument combines design features from the existing AC Missouri monitor and the DC Tjallingii monitor, plus several new innovations. It can produce three simultaneous, time-synchronized, output signals from a single insect, via AC and DC signal processing circuitry, as well as using either AC, DC, AC-plus-DC, or 0 V substrate voltage. Our research conclusively demonstrates that AC signal processing can be designed to duplicate the level of detail and fidelity of aphid waveforms previously provided solely by the DC monitor, including all R- and emf-component waveforms. Availability of either AC or DC applied voltages will allow similar high-resolution recording of insects that appear to be sensitive to DC applied voltages. We also begin to determine the subtle reasons why published waveforms from older AC and DC monitors appear to differ so greatly. Our instrument is a single, flexible, universal monitor that can provide maximum, R-plus-emf waveform information from any piercing–sucking species, especially non-aphid species with sensitivity to DC applied voltage.

Recent blooms of the dinoflagellate <i>Ceratium</i> in Albert Falls Dam (KZN): History, causes, spatial features and impacts on a reservoir ecosystem and its zooplankton

A lake-wide bloom of the dinoflagellate Ceratium hirundinella, discovered in Albert Falls Dam in October 2006, exposed a significant ecological change indicative of reduced water quality in this historically mesotrophic reservoir. The spatial distribution of the bloom was examined synoptically in October 2006 and January 2007; these surveys revealed generally higher dinoflagellate densities in inshore reaches of the lake, and especially in the discharge plume of the inflowing Mgeni River. Ceratium totally dominated the phytoplankton assemblage, accounting almost completely for coincident chlorophyll levels, which generally increased with depth to generate a ‘deep’ chlorophyll maximum. Vertical oxygen profiles during the bloom differed substantially from corresponding profiles during non-bloom conditions historically typical in this reservoir. Direct count data and ordination analysis using non-metric multidimensional scaling exposed marked changes in zooplankton community structure compared to seasonally congruent non-bloom conditions in other years. Changes included the effective replacement of Moina by Bosmina, substantial reductions in Daphnia and Ceriodaphnia, and smaller but definite increases in abundance especially of calanoid copepods, as well as cyclopoid copepods and of Chaoborus, although not all of these differences were apparent in both survey months. These compositional changes are attributable to intrinsic differences in feeding biology among taxa and their associated susceptibility to the altered food environment, which was commensurate with Ceratium’s emergence. In addition, chydorid cladocerans appeared as a new (but spatially restricted) eutrophic bio-indicator component of the zooplankton, and the species diversity of cyclopoid copepods was enriched.The historical incidence of Ceratium in the lake since 1995 coincided with low NO3-N:TP values (used here as an N:P ratio proxy), particularly of inflow waters, and with broadly coincident values in the open lake. Ceratium was present but sparse in 1995, at average N:P ratios around 5.5. It disappeared in 1996 when the ratio increased radically to >10, and reappeared in 2004 after an erratic decline of the ratio to < 5 in the lake. The decline in N:P ratio of inflow waters since 1996 was clearly associated with a consistent rise in TP levels in inflows, most plausibly attributable to inputs of (Howick) wastewater treatment (WWT) plant origin. The appearance of Ceratium blooms is accordingly related to progressive elevations in mean annual P concentrations in inflows from ~40 ìg/l in 1995 to 120 ìg/l in 2007 (broadly mirrored in annual TP loadings), suggesting that improved operational efficiency (and capacity) of the WWT plant offers a plausible prospect for mitigation and reversal

Cryptic speciation at organic-rich marine habitats: a new bacteriovore annelid from whale-fall and fish farms in the North-East Atlantic

Vigtorniella ardabilia sp. nov., a new chrysopetalid annelid, is described from a whale-fall in Sweden and from sediment samples collected beneath fish farms in Norway. The new Vigtorniella species is morphologically almost identical to Vigtorniella flokati from whale-falls in the Pacific Ocean, although molecular evidence from four genes shows that they are different species. Population genetic structure and phylogenetic relationships of V. ardabilia sp. nov. were assessed using molecular data from the nuclear genes 18S and 28S, and the mitochondrial 16S and cytochrome c oxidase subunit I (COI). High levels of gene flow are reported between contrasting organic-rich environments in the North Atlantic (fish farms and whale-fall). Observations of feeding biology and habitat suggest that V. ardabilia specializes on bacterial mats, rather than on whale-falls, although the two species of Vigtorniella for which data were available show very different feeding behaviours. Our results further showed an unexpectedly low divergence rate in Vigtorniella for the mitochondrial markers, suggesting stabilizing selection. Analyses carried out with parsimony, maximum likelihood, and MrBayes all placed the genus Vigtorniella as sister group to Dysponetus, suggesting a close evolutionary link to sediment-dwelling fauna.

Eocene tortoise beetles from the Green River Formation in Colorado, U.S.A. (Coleoptera: Chrysomelidae: Cassidinae)

Abstract The fossil history of leaf beetles (Chrysomelidae) is relatively poorly documented despite an abundance of available material. Of particular interest is the origin and radiation of the diverse tortoise beetles, a derived group within Cassidinae s.l. (=Cassidinae + Hispinae) defined by the exophagous life history and specialized morphology of the immature stages. Cassidinae is also a group with relatively few fossil records that can be assigned with any degree of certainty. Here we report two of the oldest definitive tortoise beetle fossils, Eosacantha delocranioidesgen.n. et sp.n. and Denaeaspis chelonopsisgen.n. et sp.n., from the Eocene Green River Formation (ca. 47 million years old) in northwestern Colorado, U.S.A. Owing to the fine level of preservation, many important features can be observed and are coded into the recent cladistic analysis for the subfamily. Phylogenetic analysis highlights that both genera have affinities with modern lineages, one restricted to the Old World and the other restricted to the Neotropics. Although Cassidinae as a whole extend into the Cretaceous, the available information suggests that the tortoise beetles perhaps originated and diversified during the Early Tertiary. As such, the morphological and biological transitions from the leaf‐mining hispiforms to the distinctive tortoise‐like cassidiforms, with their elaborate defensive larval shields and other unique behaviours, probably took place during the latest Paleocene or earliest Eocene. These Green River fossils are the oldest yet to document the specialized morphology associated with the transition in cassidine feeding and immature biology.

Stable isotope monitoring of benthic–planktonic coupling using salt marsh fish

Salt marshes are important coastal ecosystems whose trophic function can be moni- tored with stable isotopes of abundant fish biosentinel species such as the mummichog Fundulus heteroclitus and the Atlantic silverside Menidia menidia. We compared movement patterns and feeding biology of these species in the summers of 1999 and 2000 in the Rowley River salt marsh estuary north of Boston, Massachusetts, USA. A 15 N tracer addition experiment showed that fish of both species were more resident than transient, with mummichogs resident at scales of 1 km or less. Natural abundance stable isotope C, N, and S distributions showed that mummichogs feed more strongly in the benthic food web while silversides feed more in the planktonic food web, with % benthic feeding respectively averaging 58 ± 5 and 32 ± 3% (mean ± 95% confidence limit, CL). For both species, isotope results indicated considerable individual specialization in foraging behavior, likely related to use of channel habitat versus use of the marsh. Power analysis showed that mea- suring 3 composite samples each comprising 10 to 15 individual fish should provide relatively low errors of 0.5‰ (95% CL) or less around stable isotope averages. Use of such composite samples in monitoring programs will allow detection of significant temporal and spatial changes in benthic- planktonic coupling for salt marsh ecosystems, as recorded in average fish diets. Analyzing some individual fish also is recommended to obtain more detailed information on fish food sources, feed- ing specializations, and end-member isotope values used in estimating importance of benthic and planktonic food sources.

Xenoturbella (Deuterostomia) probably feeds on dissolved organic matter

The enigmatic deuterostome Xenoturbella does ubiquitously contain exogenous nucleic acids. This has been used in several papers as proof of selective feeding by Xenoturbella on nuculid bivalves. However, their feeding biology is unknown and exogenous nucleic acids might not originate from their main nutrient source. I have examined the possible pathways of nutrient uptake. The animals neither took up cells nor dissolved dyes through the ‘mouth’. Instead, they possessed extensive pinocytosis through the epidermis. Therefore, it is probable that the main source of nutrients is dissolved organic matter uptaken through the epidermis. This does not exclude that phagocytosis in the gastrodermis does occur, e.g. due to direct expose of the gastrodermis during asexual reproduction. The ubiquitously present exogenous nucleic acids in Xenoturbella probably do originate from such events and not from their main food source.

High altitude mountain streams as a possible refuge habitat for the catfish Amphilius uranoscopus

Amphilius uranoscopus is a catfish species, restricted to rivers and streams in east, southern and central Africa. It is likely to be displaced due to both competition and predation by exotic trout and other introduced fish. In high altitude mountain streams it can be the only species occurring, which means that this habitat may act as a refuge for this species. Ecosystems like this are threatened by habitat alteration and are therefore in need of protection. The abiotic environment, population structure, behavior and feeding biology of Amphilius uranoscopus were studied in a small, high-altitude perennial tributary of the Limpopo River in the Soutpansberg mountain range, Limpopo Province, South Africa, during 2005–2006. Here A. uranoscopus showed nocturnal behavior. It used dark hollow crevices in rapids as shelters during the daytime. The rapids are characterized by a high flow rate, high dissolved oxygen content and coarse riverbed substrate consisting mainly of boulders without fallen leaves. In contrast to the adults, juveniles found shelter among the fallen leaves in pools. At night, A. uranoscopus moved out of the rapids into the open water of the pools. The main food of A. uranoscopus consisted of macroinvertebrates, mainly Trichoptera larvae. Amounts of algae and detritus in its diet were negligible. A. uranoscopus foraged mainly in rapids and on rock surfaces, spending less time foraging between the fallen leaves at the bottom of pools, in open water, at the surfaces of bottom and bank and near the water surface. At the water surface, it also fed opportunistically on terrestrial insects that dropped into the stream, like flying termites. A. uranoscopus was the top predator of the stream system and reached a high density (0.71 fish m−2). There was no competition from other fish species at the study site as they were lacking. A. uranoscopus showed a striking ability to climb and cling on to vertical substrates to conquer waterfalls and very shallow streams that sometimes become dry, using its fins, adhesive body and protruding mouth teeth.

Telemetry System for Assessing Jaw-Muscle Function in Free-ranging Primates

In vivo laboratory-based studies describing jaw-muscle activity and mandibular bone strain during mastication provide the empirical basis for most evolutionary hypotheses linking primate masticatory apparatus form to diet. However, the laboratory data pose a potential problem for testing predictions of these hypotheses because estimates of masticatory function and performance recorded in the laboratory may lack the appropriate ecological context for understanding adaptation and evolution. For example, in laboratory studies researchers elicit rhythmic chewing using foods that may differ significantly from the diets of wild primates. Because the textural and mechanical properties of foods influence jaw-muscle activity and the resulting strains, chewing behaviors studied in the laboratory may not adequately reflect chewing behaviors of primates feeding in their natural habitats. To circumvent this limitation of laboratory-based studies of primate mastication, we developed a system for recording jaw-muscle electromyograms (EMGs) from free-ranging primates so that researchers can conduct studies of primate jaw-muscle function in vivo in the field. We used the system to record jaw-muscle EMGs from mantled howlers (Alouatta palliata) at Hacienda La Pacifica, Costa Rica. These are the first EMGs recorded from a noncaptive primate feeding in its natural habitat. Further refinements of the system will allow long-term EMG data collection so that researchers can correlate jaw-muscle function with food mechanical properties and behavioral observations. In addition to furthering understanding of primate feeding biology, our work will foster improved adaptive hypotheses explaining the evolution of primate jaw form.

Feeding strategy of the megamouth shark Megachasma pelagios (Lamniformes: Megachasmidae)

The feeding biology of the planktivorous megamouth shark Megachasma pelagios was investigated. Morphological examination disclosed that the megamouth has a suite of unique characteristics among sharks, such as large mouth, large bucco‐pharyngeal cavity, elongate jaw cartilages, long palatoquadrate levator and preorbital muscles, long ethmopalatine ligament and elastic skin around the pharynx. The combination of these characters suggests that the megamouth shark performs engulfment feeding that is typically seen in the rorqual and humpback whales. Engulfment is a new feeding method for sharks, and the detailed mechanism of the engulfment feeding is discussed.

Factors promoting marine invasions: a chemoecological approach.

The Mediterranean Sea is losing its biological distinctiveness, and the same phenomenon is occurring in other seas. It gives urgency to a better understanding of the factors that affect marine biological invasions. A chemoecological approach is proposed here to define biotic conditions that promote biological invasions in terms of enemy escape and resource opportunities. Research has focused on the secondary metabolite composition of three exotic sea slugs found in Greece that have most probably entered the Mediterranean basin by Lessepsian migration, an exchange that contributes significantly to Mediterranean biodiversity. We have found toxic compounds with significant activity as feeding deterrents both in the cephalaspidean Haminoea cyanomarginata and in the nudibranch Melibe viridis. These findings led us to propose aposematism in the former and dietary autonomy in producing defensive metabolites in the latter case, as predisposing factors to the migration. In the third mollusk investigated, the anaspidean Syphonota geographica, the topic of marine invasions has been approached through a study of its feeding biology. The identification of the same compounds from both the viscera of each individual, separately analyzed, and their food, the seagrass Halophila stipulacea, implies a dietary dependency. The survival of S. geographica in the Mediterranean seems to be related to the presence of H. stipulacea. The initial invasion of this exotic pest would seem to have paved the way for the subsequent invasion of a trophic specialist that takes advantage of niche opportunities.

Precision of ingestion time and evacuation predictors for individual prey in stomachs of predatory fishes

Without evaluating precision, gastric evacuation models in combination with stomach data are widely used to investigate the feeding biology of wild predatory fishes. Assuming each predator individual to operate with its own evacuation rate parameter, the precision of estimated ingestion times for individual prey in the stomachs of predatory fishes was derived in this study. This way, the variability of gastric evacuation not accounted for by a deterministic model of gastric evacuation was described. The variability of initial body mass of ingested prey was included as well. General values 0.03 and 0.10 of the coefficients of variation σ m and σ e were obtained for the square root of initial prey mass and the evacuation rate parameter, respectively. They were estimated from length–mass data on a variety of fresh prey fishes and from data on gastric evacuation in the predatory gadoids whiting ( Merlangius merlangus), Atlantic cod ( Gadus morhua), and saithe (pollock) ( Pollachius virens). Deriving the variance of gastric evacuation rate, evacuation time, and remaining prey mass, the study also established a basis for statistical analyses of the results obtained from laboratory experiments on gastric evacuation.

Predicting ingestion times of individual prey from information about stomach contents of predatory fishes in the field

In contrast to previous approaches, and incorporating interactions between individual prey in the stomach, the cylinder model of gastric evacuation predicted accurately the ingestion times of individual prey recovered from stomachs of predatory gadoids sampled in laboratory experiments. For application to field situations, estimates of the variance σ τ 2 = ( σ τ , e 2 + σ τ , m 2 ) of the predicted time interval τ between prey ingestion and stomach sampling were obtained from generalised considerations about the errors of estimated gastric evacuation rate ( σ τ,e ≅ 0.10 τ) and prey size at ingestion ( σ τ, m increased from 1 h to 2.5 h with increasing number and body size of other prey in the stomach). The bias originating from non-observable prey (that were completely evacuated from the stomach prior to sampling) may amount to more than 20% and should be taken into consideration. In contrast, the sensitivity of τ to estimated body lengths of other prey recovered as small remains from the stomach was generally low. These error and bias considerations render possible an appraisal in advance of the precision and the accuracy and, so, of the usefulness of the method in specific field studies on the feeding biology of predatory fishes.

Reproductive and feeding biology of the endangered fiery redfin, Pseudobarbus phlegethon (Barnard 1938) (Teleostei: Cyprinidae), in the Noordhoeks River, South Africa

The aim of this study was to contribute to the knowledge on the reproductive and feeding biology of the endangered Pseudobarbus phlegethon (Barnard 1938) in the Olifants River system, by providing estimates of its maturity, reproductive periodicity and the diet in the Noordhoeks River. The study was based on available specimens, stored in the fish collection of the South African Institute for Aquatic Biodiversity, that were collected by electrofishing between March 1996 and July 2005. A total of 158 fish were examined. The sex ratio was 1:1. Maturity was validated histologically. The length at first maturity was 33.2mm SL for males and 35.5mm SL for females. Gonadosomatic index and the proportion of ripe fish indicated a spawning peak in October. The ratio between gut length and fork length was consistent with carnivorous cyprinid species. Foregut contents were dominated by invertebrate remains (frequency of occurrence (FO) = 75%), but also contained filamentous algae (FO = 54%), sand (FO = 53%) and detritus (FO = 45%). The number of invertebrate prey found in the foregut ranged from 0.3 ± 0.6 (mean ± standard deviation) in May 1998 to 33 ± 21.5 in October 1998. The invertebrate prey was predominantly aquatic and the family Chironomidae was most important, contributing >80% to the index of relative importance in most months. The significance of these results is discussed with regard to the conservation of this species.

Food capture kinematics in the deep-water chain catshark Scyliorhinus retifer

The chain catshark (Scyliorhinus retifer) is a member of one of the most well studied groups of elasmobranchs (Order: Carcharhiniformes), yet its feeding strategy is unknown due to the inaccessible deep water environment in which it lives (greater than 200 m). To investigate the feeding biology of captive S. retifer, high-speed videography was used to document the kinematic events during capture of two differently sized fish pieces, ‘large’ (scaled to the mouth width), and ‘small’ (scaled to one-half the mouth width). Despite a significant delay in the timing of select kinematic variables for large food captures, a multivariate analysis of the feeding behaviour indicated that overall, food capture kinematics and strike behaviour in S. retifer were not statistically different between large and small items (MANOVA, Wilks' Lambda P =0.598, df=4,24). Food capture in S. retifer was suction-dominant, with items being drawn into the mouth about twice the distance that the predator moved. While suction-dominant food capture appears to be an advantage to benthic predators, it contrasts sharply with the phylogenetic position of S. retifer among several ram-feeding carcharinoid sharks including Cephaloscyllium ventriosum, a member of the same family (Scyliorhinidae). Thus, feeding mode in carcharinoid sharks seems to reflect their ecology and does not appear to have been phylogenetically constrained.