Attractive Prey Research Articles

Records of drill holes and repair scars on Rectithyris subdepressa (Brachiopoda) from the Maastrichtian Kallankurichchi Formation, India

In the post-Paleozoic communities, brachiopods are generally thought to be less attractive prey to predators than bivalves. However, recent studies have documented significant predation pressure on brachiopods throughout the Mesozoic and Cenozoic. The present study is aimed to document predation pressure on the Maastrichtian Rectithyris subdepressa from the Kallankurichchi Formation of the Cauvery Basin, India. While drilling intensity is a direct measure, repair scar frequency measures failed, non-lethal attacks. A drilling intensity of 7% and repair scar intensity of 4% is observed in the present study. These results, along with the stereotype of predatory behavior, such as the preference of size and location of the attack, indicate that both drilling and durophagous predators preyed upon Rectithyris subdepressa and the attacks are not accidental by nature. Although both predatory drill holes and repair scars could be successfully identified, specific groups could not be identified as the predators responsible for these attacks. While previous studies suggested a comparatively lower predation pressure on brachiopods than sympatric bivalves, brachiopods are the only drilled taxa in the Kallankurichchi Formation. While bivalves are the most abundant component, the large size and thicker shell of the epifaunal bivalves may explain the absence of drilling predation on the bivalves.

Retracted: A novel optimized Bat Extreme Learning intrusion detection system for smart Internet of Things networks

SummaryRapid growth in technology has triggered the exponential growth in an advancement of the profoundly associated ubiquitous biological system of unavoidable gadgets, all things considered, called as Internet of Things (IoT). Although these devices make everyone's life as flexible and comfortable, they also suffer from various security breaches. Current scenario of security systems which are employed to safeguard the IoT devices are still in darker side, which has been considered as attractive prey for the attackers. This paper proposes the novel BEL three‐tier intrusion detection architecture which is based novel bat optimized extreme learning machines to detect the various cyber‐attacks over the IoT network. The proposed system consists of (1) design of scalable IoT deployable software which is used to collect the data which are used to classify the different behaviors of IoT networks and (2) data analyzer mechanism (DAM) which analyzes the various malicious characteristics of IoT networks after incurring the attacks in the networks and classifies the type of attacks that has been injected. The real‐time scenario of smart IoT networks for smart automation has been created using API NDNOMNeT which is an extension of OMNeT++ in which the 100 IoT devices has been deployed and attack methodology has been created by Python API. The efficiency of the projected IDS planning has been evaluated on the above test beds, deploying different attacks categories such as denial of services (DoS), man in middle (MIM)/spoofing, replay, and data leakage. The experiments demonstrate that the performance of the proposed IDS architecture has outperformed the other existing learning‐based IDS in terms of accuracy, sensitivity, time complexity, and reliability.

Ранньомезолітичні помешкання в гроті Шпан-Коба (Крим, Україна)

Shpan-Koba Grotto is currently the only stratified Mesolithic and Neolithic site on the plateau of the First Range of the Crimean Mountains (Yayla). Lower Early Mesolithic cultural layers of the site (archaeological unit 3) have exceptional preservation due to the rapid accumulation of sediment and infrequent settlement of the grotto. Their planigraphy, number and composition of the artifacts can tell about the peculiarities of the economical use of the landscapes and rock shelter of the Crimean highlands at that time. Cultural layers of archaeological unit 3 date back to time from 11500 to 7600 years cal BP, which belongs to Early Preborial. At this time, the climate was colder and wetter than today, the plateau of the Yayla around Shpan-Koba was covered by mesofit steppes, pine, birch and juniper grew on the slopes of the mountains. According to archaeozoological data, the fauna of the Yayla included such representatives of steppe landscapes as saiga and horse, and simultaneously typical forest animals — red deer, brown bear and lynx. All cultural layers of the unit 3 are very similar. They belong to the type of "ephemeral": are represented by small fires, few bones of hunted animals and single flint artifacts. The layers were left by the bearers of the Swiderian culture, due to very few flint artifacts, among them: swidrian points, segment, backed blades, straight dihedral burin, end-scrapers. More than half of the found flint artifacts are retouched tools, the rest — blades and flakes, have the traces of use in the form of macro retouch. Such composition of the flint inventory indicates on the hunters (“expeditional”) character of the habitations in the Shpan-Koba grotto. The planigraphy of all layers of the unit 3 was similar too. It corresponds to classic ethnographical «Drop-Toss model» be L. Binford, which describe the organization of the living space around the hearth by a group of people from one to five people (Binford 1978; 1983). The central object in each of the cultural layers was one hearth about one meter in diameter with the thin charcoal lens and little piece of burned clay under it. Three concentric zones were traced around the hearths on the western, southern, and southeastern sides: 1) without artifacts; 2) with little bones and flint artifacts (Drop zone); 3) with bigger bones (Toss zone). The "asymmetrical" location of the finds in relation to the hearths indicates the absence of artificial housing in the grotto. The only exception is the habitation of the 3-5/6 cultural layer, in which a small wall of stones was excavated. For it, the "symmetrical" location of the finds around the hearths can be assumed to be an artificial structure made of plant materials, such as a brush windbreak or a hut. The windbreak could also exist in the habitation of layer 3-2, judging by the lack of a Toss zone in the south-western part. The presence of only one hearth in each of the cultural layers, the location of the artifacts relative to the hearth and their number, the composition of hunting prey, etc., evidence, that Shpan-Koba grotto in the Early Mesolithic was used as dwelling of little group (4—5 people). The occupation, probably, was very short terming, due to small and low-power fires, very few bones of animals and single flint artifacts, which were found in сertain layers. Their purpose was recreation, skinning and butchering of hunting prey, repair of hunting equipment and more. Seasonality of the Early Mesolithic dwellings in the grotto, due to archaeozoological data, fall on warm time — spring and summer (Benecke 1999, s 83, abb. 10). The aim of the swidrian people’s hunting expeditions to Yaila was hunting, first, on the saiga and red deer, which migrated from from the steppes of northern Crimea. The number of the red deer also increased in the First Range of the Crimean Mountains during warm seasons. The bones of the brown bear in many layers suggest that it was also an attractive prey. Key words: Crimea, Ukraine, Early Mesolithic, habitation, seasonal migrations, Swiderian.

Drug Dealers’ Rational Choices on Which Customers to Rip-Off

a b s t r a c t Background: Drug dealers are infamous for overcharging customers and handing over less than owed. One reason rip-offs frequently occur is blackmarket participants have limited access to formal means of dispute resolution and, as such, are attractive prey. Yet drug dealers do not cheat every customer. Though this is implicitly understood in the literature, sparse theoretical attention has been given to which customers are ripped-off and why. Methods: To address that lacuna, this paper uses the rationality perspective to analyze qualitative data obtained in interviews with 25 unincarcerated drug sellers operating in disadvantaged neighborhoods of St. Louis, Missouri. Results: We find that dealers typically rip-off six types of customers: persons who are strangers, first-time or irregular customers; do not have sufficient money on hand to make a purchase; are uninformed about going market rates; are deemed unlikely to retaliate; are offensive; or are addicted to drugs. Dealers target these groups due to perceiving them as unlikely to be repeat business; not worth the hassle of doing business with; unlikely to realize they are being ripped-off; in the wrong and thus deserving of payback; and, unwilling to retaliate or take their money elsewhere. Conclusion: Our findings are discussed in relation to their practical implications, including the importance of giving blackmarket participants greater access to law, and how customers may prevent being ripped- off.

Predation of the round goby (Neogobius melanostomus Pallas, 1814) on Atlantic herring eggs in the Western Baltic Sea

ABSTRACTThe Ponto-Caspian round goby (Neogobius melanostomus Pallas, 1814) is a prominent invasive species in many European waters. Eggs of the Western Baltic Spring Spawning Atlantic herring might be attractive prey for the invasive round goby during the spawning season. However, investigations of the small fish fauna in an important spawning area of herring, which was characterized by high densities of macrophytes, indicated a spatio-temporal mismatch of round goby and herring spawn in spring, at least on some of the known important spawning beds situated on vegetated sandy bottoms. In contrast, a spatio-temporal overlap between round gobies and herring spawn was observed in a more structured area, characterized with stones, where round gobies’ stomachs were sampled. Further field study results suggest that large round gobies (> 10 cm) do not feed on herring eggs, while smaller round gobies (< 10 cm) do so. To support these results, we conducted laboratory feeding experiments with round gobies. When C. crangon, M. edulis and herring eggs were offered simultaneously, round gobies preferred C. crangon. M. edulis was preferred over herring eggs when C. crangon was absent. The predatory impact of the round goby on herring eggs seems to be of minor importance compared to other species, such as three-spined stickleback or perch. Applying the same data, different food ‘preference indices’ revealed a discrepancy in preference between indices. Therefore, we propose a modified food preference index (mE), taking into account four important parameters and combining benefits of two commonly applied indices.

The diet of reservoir perch before, during and after establishment of non-native tubenose goby

In recent decades, gobiid species have increased their distribution throughout Europe and now often represent the dominant genus along many rivers and canals. In this study, we assessed the role of tubenose goby (Proterorhinus semilunaris) as a prey species of native perch (Perca fluviatilis) in a lowland reservoir soon after their initial introduction in 1994 (sampling started 1998) and 17 years after establishment (2011–2012). We compare these data with perch diet composition from before introduction (1981–1982). Our data indicate that tubenose gobies quickly became the dominant species along the reservoir bankside, making them an attractive prey for ≥1 + perch. There was a clear increasing trend in the numbers of larger perch caught along the rip-rap, with the largest fish clearly specialising on gobies. As such, introduction of tubenose gobies has had a pronounced effect on food web and population dynamics along the littoral zone. While goby numbers appear to have dropped significantly in recent years, apparently due to predation pressure, further studies are needed to assess whether such changes have had any general impact on population and food web dynamics within the reservoir.

Pseudomonas aeruginosa lasI/rhlI quorum sensing genes promote phagocytosis and aquaporin 9 redistribution to the leading and trailing regions in macrophages.

Pseudomonas aeruginosa controls production of its multiple virulence factors and biofilm development via the quorum sensing (QS) system. QS signals also interact with and affect the behavior of eukaryotic cells. Host water homeostasis and aquaporins (AQP) are essential during pathological conditions since they interfere with the cell cytoskeleton and signaling, and hereby affect cell morphology and functions. We investigated the contribution of P. aeruginosa QS genes lasI/rhlI to phagocytosis, cell morphology, AQP9 expression, and distribution in human macrophages, using immunoblotting, confocal, and nanoscale imaging. Wild type P. aeruginosa with a functional QS system was a more attractive prey for macrophages than the lasI/rhlI mutant lacking the production of QS molecules, 3O-C12-HSL, and C4-HSL, and associated virulence factors. The P. aeruginosa infections resulted in elevated AQP9 expression and relocalization to the leading and trailing regions in macrophages, increased cell area and length; bacteria with a functional QS system lasI/rhlI achieved stronger responses. We present evidence for a new role of water fluxes via AQP9 during bacteria–macrophage interaction and for the QS system as an important stimulus in this process. These novel events in the interplay between P. aeruginosa and macrophages may influence on the outcome of infection, inflammation, and development of disease.

Drug dealers’ rational choices on which customers to rip-off

BackgroundDrug dealers are infamous for overcharging customers and handing over less than owed. One reason rip-offs frequently occur is blackmarket participants have limited access to formal means of dispute resolution and, as such, are attractive prey. Yet drug dealers do not cheat every customer. Though this is implicitly understood in the literature, sparse theoretical attention has been given to which customers are ripped-off and why. MethodsTo address that lacuna, this paper uses the rationality perspective to analyze qualitative data obtained in interviews with 25 unincarcerated drug sellers operating in disadvantaged neighborhoods of St. Louis, Missouri. ResultsWe find that dealers typically rip-off six types of customers: persons who are strangers, first-time or irregular customers; do not have sufficient money on hand to make a purchase; are uninformed about going market rates; are deemed unlikely to retaliate; are offensive; or are addicted to drugs. Dealers target these groups due to perceiving them as unlikely to be repeat business; not worth the hassle of doing business with; unlikely to realize they are being ripped-off; in the wrong and thus deserving of payback; and, unwilling to retaliate or take their money elsewhere. ConclusionOur findings are discussed in relation to their practical implications, including the importance of giving blackmarket participants greater access to law, and how customers may prevent being ripped-off.

Prey Choice During the South African Middle Stone Age: Avoiding Dangerous Prey or Maximising Returns?

Scrutinising prey choice allows the testing of hypotheses on whether the hunting capabilities of Middle Stone Age (MSA) people were as sophisticated as those of Later Stone Age hunter–gatherers. I apply an optimal foraging perspective to investigate whether MSA prey choice was constrained by the danger associated with hunting certain species. Here, I study the relative importance of elands, buffalo and suids. Eland was the most attractive prey to hunter–gatherers because it is large and docile. Buffalo and suids are more aggressive. When additional species to eland needed to be exploited, we would expect unsophisticated hunters to prefer the smaller suids over buffalo. If hunting prowess was sufficient to deal with both buffalo and suids, buffalo should be preferred. Due to their size, exploitation of buffalo would be more profitable than exploitation of suids. I show that, taking environmental circumstances into account, buffalo were preferred to suids, suggesting that MSA people were capable, sophisticated hunters.

5,000 Miles to Freedom: Ellen and William Craft's Flight from Slavery (review)

Reviewed by: 5,000 Miles to Freedom: Ellen and William Craft's Flight from Slavery Elizabeth Bush Fradin, Judith Bloom 5,000 Miles to Freedom: Ellen and William Craft's Flight from Slavery; by Judith Bloom Fradin and Dennis Brindell Fradin. National Geographic, 200696 p illus. with photographs Library ed. ISBN 0-7922-7886-0$29.90 Trade ed. ISBN 0-7922-7885-2$19.95 R Gr. 5-10 Contemporary Wendell Phillips described the Crafts' near-miraculous escape from slavery in the deep South as "one of the most thrilling tales in the nation's annals." Readers are bound to agree as the Fradins trace their treacherous journey and its equally perilous aftermath from the moment the Crafts decided to pose as a Southern gentleman (light-skinned Ellen) and his slave (darker William) and made their way to Philadelphia in plain view via rail and water. Hunger, sleeplessness, and brushes with imminent discovery nearly resulted in disaster, and even the expected safety of Philadelphia, and later Boston, proved illusory as a more draconian Fugitive Slave Law made the celebrated runaways attractive prey. Their sojourn in Great Britain and later work in the post-bellum United States demonstrate their contribution to African-American advancement but also paint a bittersweet picture of two people who longed for a normal, private life and were instead laden with more public responsibilities. Several pieces of pictorial and documentary evidence are reproduced here, but most illustrations try to capture the sense of the period through photos, engravings, and maps. Source notes, bibliography, and index will aid report writers, but readers are just as likely to peruse this title for their own noncurricular interest. Copyright © 2006 The Board of Trustees of the University of Illinois

Hydrothermal vent octopuses of Vulcanoctopus hydrothermalis, feed on bathypelagic amphipods of Halice hesmonectes

A feeding frenzy of 12 octopuses of Vulcanoctopus hydrothermalis was observed from the manned submersible ‘Alvin’ at Parigo, a 2620 m deep hydrothermal vent on the East Pacific Rise. The aggregated benthic octopuses at the active vent used their arms and webs to forage on bathypelagic amphipods, apparently targeting their attacks based on contact with the swarming amphipods. Individual octopuses wrapped their arms around the mantles of smaller octopuses, apparently in competition for prey. Although members of the prey species, Halice hesmonectes, are individually small (&lt;5 mm long), the density of their swarms may make them attractive prey for the octopus. Inactive sulphide spires encircled part of this vent site; octopuses that climbed these spires had easy access to the dense prey swarms. The presence of the spires may uniquely enable this site to support simultaneous foraging by large numbers of octopuses.

Prey vulnerability and active predator choice as determinants of prey selection: a carabid beetle and its aphid prey

Petri dish experiments were conducted to study various aspects of prey selection in the predatory carabid Poecilus cupreus. The potential influence of active and passive prey selection, relative prey frequencies and hunger state of the carabid beetle were investigated with respect to the predation of aphids. For prey the focus was on the aphid Rhopalosiphum padi, and the fruit fly Drosophila melanogaster and the house cricket Acheta domestica were used as prey for comparison. Both search time and handling time for live prey items was longest for A. domestica, shorter for D. melanogaster and shortest for R. padi. Absolute maximum consumption in numbers was lowest for A. domestica, whereas the consumed numbers of D. melanogaster and R. padi were not significantly different. In the prey preference experiments with live prey (passive selection), P. cupreus ranked prey types in the order R. padi &gt; D. melanogaster &gt; A. domestica. Due to the predation activity of P. cupreus, prey frequencies changed in the course of the experiments; however, the relative abundance of alternative prey did not affect prey preferences. Although starved P. cupreus consumed slightly more prey individuals, the different saturation level of the carabids had no influence on prey preferences. In the preference experiment with dead prey (active choice), rank order of prey selection was reversed: P. cupreus now selected prey types in the order A. domestica &gt; D. melanogaster &gt; R. padi. The results indicate that for P. cupreus, the cricket A. domestica is the most attractive prey, Drosophila is at an intermediate position, and R. padi is the least attractive one. Nevertheless, in live prey tests P. cupreus preferred the aphid R. padi, probably because this prey type was easier to catch. The results suggest that the outcome of predator–prey encounters in P. cupreus is determined by prey vulnerability rather than by active choice of the carabid predator. Therefore, it is argued that the predation impact of carabid beetles on aphids depends not only on the presence and value of alternative prey, but also strongly on the escape efficiencies of the different prey species. Hence, in studying prey preferences of carabids with the aim of evaluating their effectiveness against aphids, a closer examination is necessary of the behavioural parameters affecting the outcome of specific carabid–prey encounters.

Cercopagis pengoi — New Important Food Object of the Baltic Herring in the Gulf of Finland

The non-indigenous predaceous cladoceran Cercopagis pengoi (Ostroumov) was found for the first time in the Gulf of Finland in 1995. After this invasion, the diet of the Baltic herring Clupea harengus mebras and its seasonal dynamics were investigated in the coastal waters of SE Finland. The specimens of C. pengoi were not present in plankton samplings until the end of July when the surface water temperature reached 13.5 °C. From the beginning of August to the end of October Cercopagis was found in all the plankton samples. Before the occurrence of Cercopagis, the diet of herring consisted mostly of Eurytemora affinis and Bosmina coregoni maritima. During August to mid-October, C. pengoi was the main food source. In November, after the disappearance of C. pengoi from the plankton, B. coregoni maritima became the main prey object. Both the smallest and largest size classes of the herrings investigated consumed C. pengoi. Females with overwintering eggs are the most attractive prey for herrings. The overwintering eggs of C. pengoi, due to their very hard capsules, seem to pass undamaged through the stomach and intestines of herring. C. pengoi started to play a highly important role in the zooplankton community in the waters of SE Finland, and its abundance is not too dependent upon the annual temperature fluctuations. The Baltic herring population has substantially changed its diet in this area, and now it prefers the new-comer C. pengoi.

Cercopagis pengoi — New Important Food Object of the Baltic Herring in the Gulf of Finland

The non-indigenous predaceous cladoceran Cercopagis pengoi (Ostroumov) was found for the first time in the Gulf of Finland in 1995. After this invasion, the diet of the Baltic herring Clupea harengus mebras and its seasonal dynamics were investigated in the coastal waters of SE Finland. The specimens of C. pengoi were not present in plankton samplings until the end of July when the surface water temperature reached 13.5 °C. From the beginning of August to the end of October Cercopagis was found in all the plankton samples. Before the occurrence of Cercopagis, the diet of herring consisted mostly of Eurytemora affinis and Bosmina coregoni maritima. During August to mid-October, C. pengoi was the main food source. In November, after the disappearance of C. pengoi from the plankton, B. coregoni maritima became the main prey object. Both the smallest and largest size classes of the herrings investigated consumed C. pengoi. Females with overwintering eggs are the most attractive prey for herrings. The overwintering eggs of C. pengoi, due to their very hard capsules, seem to pass undamaged through the stomach and intestines of herring. C. pengoi started to play a highly important role in the zooplankton community in the waters of SE Finland, and its abundance is not too dependent upon the annual temperature fluctuations. The Baltic herring population has substantially changed its diet in this area, and now it prefers the new-comer C. pengoi.

Hermit Crabs in the Diet of Pigeon Guillemots at Kachemak Bay, Alaska

-Guillemots (Cepphus spp.) feed their chicks a diet that is almost exclusively fish. We observed Pigeon Guillemots (C. columba) at two colonies in Alaska where hermit crabs (Crustacea: Anomura) were a major part of the diet for some nestlings. Hermit crabs were delivered to three of five observed nests at one colony, comprised between 2% and 22% of the items delivered at those nests, and were the second most common food type at one nest. Hermit crabs may be an attractive prey item when lipid-rich forage fish are scarce, and crabs living in gastropod shells that have been softened by encrustations of Suberites sponges may be vulnerable to guillemot predation. Received 11 March 1998, accepted 1 April 1998.

Walking, Jumping, Collaboration, and Competition Characterize Race to Cystic Fibrosis Gene

THE INDENTIFICATION of the cystic fibrosis (CF) gene earlier this month culminated one of the most concerted and competitive efforts in the history of medical genetics. Cystic fibrosis' high incidence (one in 2000 births in the United States), severity, and resistance to prenatal diagnosis has made its gene an especially attractive prey for molecular biologists and geneticists. The race to find the gene began, for all practical purposes, in 1980 with the discovery that restriction fragment length polymorphisms (RFLPs), stretches of DNA that vary among people, could serve as diagnostic markers if they were close enough to a disease gene to be inherited with the gene most of the time. By analyzing the DNA from several members of an affected family, it was often possible to tell which RFLP haplotype signaled the disease in that family. Lap-Chee Tsui, PhD, became involved in the quest to find RFLPs associated with the

The prey localisation model: A stability analysis

This paper analyses the “Prey Localisation Model” (House, 1984), for animals that are unable to verge their eyes. The Prey Localisation Model selects a single point or a portion of the scene in its visual space. In particular it imitates the behaviour of frogs and toads of selecting the closer target when two equally attractive prey are presented to it. The model achieves its goal by tightly coupling two prey selection processes, one for each eye, with lens accommodation. In this paper we offer a stability analysis of the model, and show how lens accommodation, i.e. adjustment in the focal length of the lens, biases the selection of the proximal target. We examine the properties of the model that are responsible for its behaviour and derive a set of conditions which guarantees the localisation of the correct target.

The prey localisation model: a stability analysis.

This paper analyzes the "Prey localisation Model" (House 1984), for animals that are unable to verge their eyes. The Prey localisation Model selects a single point or a portion of the scene in its visual space. In particular it imitates the behaviour of frogs and toads of selecting the closer target when two equally attractive prey are presented to it. The model achieves its goal by tightly coupling two prey selection processes, one for each eye, with lens accommodation. In this paper we offer a stability analysis of the model, and show how lens accommodation, i.e. adjustment in the focal length of the lens, biases the selection of the proximal target. We examine the properties of the model that are responsible for its behaviour and derive a set of conditions which guarantees the localisation of the correct target.

Feeding biology of the sea-starAstropecten irregularisPennant

Abstract As other species of Astropecten, A. irregularis rests buried in the substrate between periods of feeding activity. These usually occur at twilight hours. The sea-star can sense and localize prey buried underneath it with great precision. Prey animals are quickly pushed through the mouth opening and into the stomach by the (sucker-less) tube feet surrounding the mouth. Astropecten cannot dig deep enough to seize deep-sitting prey such as e. g. members of the Tellinidae and non-juvenile Mya spp. It feeds mainly on small animals, but may occasionally swallow very large prey. Digestion of prey takes place in pockets of the stomach wall and requires that lobes of the stomach can be inserted and applied in direct contact with the digestible tissue. Protected prey organisms such as bivalves with tightly appended valves cannot be digested before they succumb and start to gape permanently due to a lack of oxygen. Since oxygen requirements differ, prey are retained in the stomach for varying periods of time. Whereas Spisula subtruncala, for example, is digested and the empty shells ejected well within 24 hours, specimens of (non-juvenile) Venus gallina and Corbula gibba may be retained for 2-3 weeks or more. Certain prey as e. g. non-juvenile Natica spp., V. gallina of all sizes and C. gibba more than 2-3 mm long may often be ejected alive after a shorter or longer stay in the sea-star stomach. Astropecten is a selective feeder, mainly engulfing bivalves, among which it exhibits a distinct preference for species with a low resistance to anaerobic conditions. This behaviour and a pronounced tendency to feed primarily on juvenile specimens ensure that the digestible matter of swallowed prey in most cases may be quickly assimilated. Metabolic rate may seemingly be used as an index for attractiveness of bivalve prey, but the real stimulus is probably one or several metabolic end products. Food uptake is significantly reduced in the absence of “first class” food species. If only highly undesirable food species are present, the sea-star may almost stop feeding and loose weight. A medium sized Astropecten may pick up and digest more than 400 S. subtrullcata spat within 24 hours and theoretically destroy some 30,000 spat annually. Among other bivalves taken in considerable numbers are Mya truncata and Montacuta ferruginosa. Newly settled. Echinocardium cordatum are also heavily preyed upon, at least when attractive molluscan species are absent or scarse. In Danish waters fee.ding practically stops below 40 C. Above this temperature the feeding rate depends highly on the density and types of potential prey spesies present. In the 0resund, for example, feeding rates are usually low at the most favourable temperature level because such attractive prey as O-group S. subtruncata are exterminated while the tempereture still is low. This results in undernourishment and stops reproduction. At 11-16°C, small specimens fed on attractive prey may daily consume an amount of food equal to about 18% of their own living weight, whereas adult specimens consume considerably less, i. e. about 2%. Data from the literature indicates that the majority, if not all, of the Astropecten spp. probably are selective feeders which mainly feed on molluscs.