The feeding ecology and relative abundance of mullet (Mugilidae) in Natal and Pondoland estuaries

An investigation of the feeding ecology of Mugilidae in Natal and Pondoland estuaries showed that although the diet of the eleven species is similar it varies from one estuary to another and is determined largely by the occurrence of particular food items on substrates of the preferred particle size of each species. The findings of this study support the conclusions reached by Blaber (1976) with regard to the partitioning of the food resource according to inorganic particle size. Particle sizes consumed by each species do not remain the same but vary according to locality. Within any one estuary the mullet species avoid interspecific competition by selecting particles of different sizes. The fish are always graded in the same order with regard to particle size. The relative abundance of the various species of mullet in Natal and Pondoland estuaries is probably not controlled by food or substrate requirements because most species are sufficiently flexible in their feeding ecology to cope with a wide variety of estuarine substrates.     

The biology of filter feeding teleosts in Lake St Lucia, Zululand

The biology of filter feeding teleosts in St Lucia, was studied for two years from 1976 to 1978. The three common species, Gilchristella aestuarius, Hilsa kelee and Thryssa vitrirostris were studied with the composition and cyclical nature of the zooplankton which formed their food. Stolephorus commersonii and Hepsetia breviceps which were rare were only briefly examined. The zooplankton was dominated by the calanoid Pseudodiaptomus stuhlmanni which formed > 70 % of the calorific value of the zooplankton for 70 % of the study period. The mysid Mesopodopsis africana was second in importance in terms of calorific contribution while the amphipod Grandidierella lignorum was relatively abundant. Larval forms, particularly post-veligers of Assiminea bifasciata were also important. There was a close correlation between the zooplankton cycles, both diel and annual, and the feeding, reproduction and recruitment of the three common filter feeding teleosts. G. aestuarius spent its whole life-cycle in the system and spawned in early summer when the resulting juveniles could feed on the summer zooplankton peaks. They grew at 0.5 cm month⁻¹ and attained maximum size in one year. They were non-selective taking mainly P. stuhlmanni and post-veligers. H. kelee spawned in the sea and juveniles were common in St Lucia during 1978 when they fed non-selectively, chiefly on P. stuhlmanning the summer before disappearing over the winter. The resulting offspring went through a sequence of dietary changes which were closely related to zooplankton cycles. The importance of P. stuhlmanni in the pelagic food web of St Lucia is illustrated. The species supports not only the filter feeding teleosts but indirectly the predatory fish Argyrosomus hololepidotus and Elops machnata which feed on G. aestuarius and T. vitrirostris .     

Longitudinal zonation and food of larval chironomids (Insecta: Diptera) along the course of a river in temperate Canada

The chironomid larvae of the Rouge River, Ontario, Canada, showed a longitudinal zonation which may have been influenced by water temperature and substrate composition. Species of Orthocladiinae predominated in the cooler headwaters while species of Chironomini dominated the comparatively warmer water near the estuary. In the middle section the chironomid assemblage was of a more mixed nature.
Differences occurred in both food availability and feeding between sites along the river. Within genera, there were differences in the proportions of major food items between the larval guts and the available food material sampled from the same area. In most cases (e.g. Cryptochironomus, Polypedilum and Orthocladius ) larvae selected detritus over diatoms. Some genera (e.g. Microtendipes ) changed the proportions of food items ingested seasonally, while others (e.g. Psectrocladius ) exhibited a more stable diet throughout the year. Second instar larvae appeared to seasonally adjust their diet most often (e.g. Cricotopus. Tanytarsus and Eukiefferiella ), however these changes were not just in the types of food eaten, but also in the proportions of food types consumed. Larvae of all genera continued feeding throughout the cold water conditions (<5°C) of winter. Incidence of predation was very low, for example <10% in the Tanypodinae. In the laboratory, species of Chironomini ingested and assimulated, to varying degress, isolated populations of diatoms, detritus and bacteria.     

Food and feeding habits of four species of juvenile mullet (Mugilidae) in a tidal lagoon in Ghana

Juvenile mugilid fishes, Liza falcipinnis, L. dumerilii, Mugil bananensis and M. curema , which enter the Elmina Lagoon in the Cape Coast District of Ghana, have a similar diet comprising mainly bacteria, diatoms, blue-green/green algae, protozoans, detritus and particulate organic matter. No seasonal changes in the diet and feeding activity were observed. The relative gut length (intestine to standard length ratio) and diet showed no significant changes with size of fish in all the species. All four species were diurnal feeders, but their peak feeding times differed. Interspecific competition for food was possibly limited by species preferences for substrate particles of particular size range and differences in feeding chronology.     

The Influence of Preculture Conditions and Food Quality on the Ingestion and Digestion Process of Three Species of Heterotrophic Nanoflagellates

The influence of prey characteristics such as motility and size as well as of predator characteristics such as satiation and preculturing diet on the feeding process of interception feeding heterotrophic nanoflagellates was investigated. Three species of gram-negative bacteria, one species of gram-positive bacteria, two species of cyanobacteria (Synechococcus) and inert latex particles were fed as prey particles for three species of heterotrophic nanoflagellates (Spumella, Ochromonas, Cafeteria). Ingestion rates depended on the satiation of the flagellates and especially on the filling status of the food vacuoles. In addition, the ingestion rates depended on the characteristics of the food particle and were modified by pre-culturing the flagellates on either Pseudomonas putida or Bacillus subtilis. Digestion was found to be particle-specific. Cyanobacteria were excreted a few minutes after ingestion whereas heterotrophic bacteria were stored and digested in the food vacuoles. The spectrum of ingested particles is not identical to that of digested particles and thus neither the diet of the flagellates nor their impact on bacterial communities can be calculated simply from food vacuole content. "Selective digestion" could be shown to be an important selection mechanism concerning natural food particles. The digestion strategies of Cafeteria on the one hand and Spumella and Ochromonas on the other hand may be an important factor to explain protozoan species composition and succession in the field. In addition to bacterial abundance and grazing pressure by metazooplankton, the bacterial speciescomposition as well as biochemical variations within bacterial species may influence protozoan species composition and abundance.     

Dung feeding in adult scarabaeines (tunnellers and endocoprids): even large dung beetles eat small particles

Abstract 1. The maximum size of ingested particles was determined in 15 species of adult dung beetle (Scarabaeidae: Scarabaeinae) by mixing small latex or glass balls of known diameter into the dung used as food. Twelve species (tribes Coprini, Onitini, Oniticellini, and Onthophagini) were tunnellers (making dung stores for feeding and breeding in the soil below the pat) and three species (tribe Oniticellini) were endocoprids (feeding and breeding in the dung pat itself).
2. The test species, covering a wide range of body size (fresh weights 0.05–7.4 g), ingested minute particles only (maximum diameter 8–50 µm), and there was a statistically significant but numerically small increase in particle size with body weight.
3. When the effect of body size was taken into account, taxon (tribe), ecological group (tunneller/endocoprid), and dung preference (coarse/fine) had no significant effect on the size of ingested particles.
4. Tests using two tunnelling species did not indicate that beetles use their mandibles to grind dung particles prior to ingestion.
5. The results suggest essentially the same feeding mechanism in all adult tunnelling or endocoprid scarabaeines that eat fresh dung. Larger, indigestible plant fragments are avoided by filtration, and ingestion is confined to very small particles of higher nutritional value.     

The food and feeding habits of greenback grey mullet, Liza subviridis (Valenciennes), from different habitats and at various stages of growth

An analysis of the stomach contents of Liza subviridis at various stages of growth and from different habitat types is given. Transitions in diet with respect to size were observed. Postlarval stages of less than 12 mm standard length fed only on zooplankton. The transition to bottom feeding occurred in specimens 16–20 mm, with food items consisting of zooplankton, diatoms, detrital material and inorganic sediment. The transition was complete on attaining a length of 24 mm whereby food items comprised diatoms, detrital material, filamentous algae and inorganic sediment. The relevance of this information in aquaculture is discussed. The stomach contents of adult Liza subviridis taken from different habitat types were consistent, comprising diatoms, detrital material and inorganic sediment. Filamentous algae was also consumed where available.     

Feeding patterns of four macroinvertebrate taxa in the headwaters of the Buffalo River,eastern Cape

Gut content analysis, field and laboratory observations, and food choice experiments were used to assign four abundant macroinvertebrate taxa in the headwaters of the Buffalo River, eastern Cape, to functional feeding groups. The mayfly Adenophlebia auriculata (Leptophlebiidae) was classified as a collector: brusher; while the caddisflies, Dyschimus ensifer (Pisuliidae) and Goerodes caffrariae (Lepidostomatidae), and stoneflies Afronemoura spp. (Notonemouridae) were classified as shredders. The effects of organism size, season and biotope on dietary composition were tested, with size accounting for most of the dietary variability within each taxon. Larger individuals consumed more material, larger items, and, in the case of A. auriculata, a wider variety of food-types. There was little variation in the feeding of the taxa in different seasons or biotopes. Shredders ingested mainly leaf fragments, and this, rather than the size of particles in the gut, is a more useful basis for the shredder designation. A. auriculata was the most opportunistic feeder, and items in its diet additional to fine detritus varied seasonally and in the various biotopes. Of the shredders, Afronemoura spp. and D. ensifer were more varied in their diet, augmenting the staple intake of leaf material with other items. G. caffrariae was the most specialised feeder, being exclusively a shredder, regardless of biotope or season. Despite criticisms of the applicability of the FFG concept in the literature, we conclude that these taxa can reasonably be accommodated in functional feeding classes, and that the results are useful in describing the functions performed by the organisms in the river. The relationship between feeding function and river process is emphasised: we suggest that collectors contribute primarily to organic particle retention, while shredders facilitate organic particle size reduction and mobilisation, and the enhancement of substrates for microbial colonisation. An emphasis on river function is a useful context within which to view the FFG concept.     

Food habits of Lutjanus peru (Pisces:Lutjanidae) in the coasts of Guerrero, Mexico

In this paper we describe the feeding habits of the Red snapper (Lutjanus peru) in the southern coast of Guerrero state, Mexico. This data could be relevant to local fisheries management. In total 385 full stomachs (206 from females and 179 from males) were collected monthly in 1993 and 1994, from commercial catches. Stomach contents were identified to species level when possible. Food items were grouped into taxonomically coherent groups, and their numbers, weight and frequency of occurrence obtained. The index of relative importance (IRI) was calculated for the total sample, by month, sex and size class. In 1993, a total of 42 different food items were obtained, and 43 in 1994. Food items consisted of fishes, crustaceans, and mollusks. The grouping of prey species, genera, or families rendered 14 food groups, as follows: Mollusks, Amphipods, Copepods, Stomatopods, Penaeus vannamei, Brachiuran Larvae, Stomatopods Larvae, Family Albuneidae Larvae, Other crustaceans, Anchoa ischana, Anchoa lucida, Other fishes, Salps and Unidentified organic matter. Anchoa ischana dominated the trophic spectrum in both years. Although, Amphipods, Anchoa lucida and Other fishes had important indexes in 1994. There was high variability in the diet composition by month. Nevertheless, in 1993, from February to August, crustaceans as a whole dominated the diet. In 1994, crustaceans only dominated in March and August. No differences in food habits were found between immature fish, males and females. The diet of the Red snapper varies as they grow, although the same food groups are found always. At the adult phase, in length classes over 261 mm FL, there is some degree of specialization, as they consume more fish, particularly engraulids.     

Diverse diet compositions among harpaline ground beetle species revealed by mixing model analyses of stable isotope ratios

1. Species diversities of some insect lineages have been attributed to differentiation of feeding habits among species. Our objective was to determine variation in diet composition among harpaline ground beetle species occurring in a riverside grassland. 2. We examined the diet compositions of 14 species from six genera in the spring and 10 species from two genera in the autumn. We performed measurements of nitrogen and carbon stable isotope ratios in consumers and in their potential food items, and estimated relative contributions of different food items with two mixing models, IsoSource and MixSIR. 3. IsoSource and MixSIR software gave similar results, but IsoSource tended to calculate higher contributions of principal food items and smaller percentile ranges than MixSIR. Among harparine beetle species, there were diverse food utilisation patterns among four food categories (detritivorous invertebrates, herbivorous invertebrates, C3 plants, and C4 plants). Detritivores comprised the main diets of abundant harpaline species in the spring, whereas abundant harpaline species in the autumn were primarily herbivores feeding on C4 plants, or omnivores feeding on herbivorous invertebrates and C3 plants. Seasonal changes in food use were related to seasonal changes in the abundance of each food resource. 4. Mixing model analysis of stable isotope ratios is a convenient and effective method for roughly estimating diets of many species with diverse food habits (such as ground beetles). This method can contribute to determining the trophic relationships of related insects in one ecosystem.     

Feeding habits and diet in two populations of spined loach, Cobitis taenia (L.)

SUMMARY. The feeding habits of Cobitis taenia were studied by means of monthly samples taken over a 2-year period, October 1972-October 1974, from two sites, one on the River Great Ouse at Newport Pagnell and the other at some neighbouring gravel pits. Dietury components, seasonal variation in these components, and seasonal and diurnal variation in feeding intensity were examined. The ecological niche of the food items and their size range are discussed, since both these factors appeared important in governing the micro-habitat of the fish.
The feeding activity followed a seasonal cycle with little or no feeding in the winter and a high level of feeding activity in mid-summer.
The diet showed a predominance of small food items, such as chydorids. copepods and rhizopods. These items varied in occurrence during the feeding period which appeared to be related to their own abundance, pointing to non-seleclive feeding by the fish. The small size and benthic habits of the food items, many of which are closely associated with surface layers of mud and weed, indicated a preference by Cobitis taenia (L.) for feeding in this type ot habitat and on this type of food, in contrast to the stone loach. Noemacheilus barbatulus (L.), which is believed to inhabit stony areas and take larger food items.     

Food of three upland game birds in Selengei Area, Kajiado District, Kenya

Foods taken by yellow-necked spurfowl, crested francolin and helmeted guinea-fowl were investigated over a 22-month period. Bulblets of sedge (Cyperus sp.) were the major plant item in the diet of all three species. Other foods were seeds and fruits of forbs, florets and fruits of grasses, leaves of forbs and grasses and insects. Insect use increased following the rains, as did the use of florets of the grasses. Except for Cyperus sp. there was little overlap of food items taken by the crested francolin and the guinea-fowl, but both were in competition with the yellow-necked spurfowl for some species of plants. This was probably due to size of food items, that is, there was a direct relationship between size of bird and size of foods taken. Forag ing habits also influence food intake.     

Diel diet shift of roach and its implications for the estimation of daily rations

In a small, 12 ha, mesotropic lake, roach Rutilus rutilus performed diel habitat shifts that clearly influenced the composition of their diet. During daytime, roach stayed in the littoral zone and concentrated on littoral prey. At night they were found in the pelagic zone, and pelagic prey items such as Daphnia spp. or Chaoborus flaricans dominated their food. On a seasonal scale, there were shifts in the importance of different food items and in the diel pattern of feeding intensity. Bioenergetics modelling in combination with an evacuation rate method for estimating daily rations allowed for changes in feeding modes to be taken into account, and so food item specific daily rations over the season could be determined. With the evacuation rate method applied on selected days, diel changes in diet compositions and feeding intensities could be quantitatively accounted for. When the 24 h integrated diet proportions were then used as an input parameter for bioenergetics modelling, food item specific consumption could be determined over the entire sampling season. The consideration of the diel diet shifts proved to be essential for the model output. If only the daytime or the night-time diet composition (derived from one single daily sampling) was taken into account for bioenergetics modelling, severe under- or overestimations of daily rations for specific food items resulted.     

Age class differences in the feeding behavior of captive Japanese macaques (Macaca fuscataia) in the forested and nonvegetated enclosure groups

Age class differences in feeding behavior of primates are affected by many factors, including feeding competition, foraging skills, habitat type, food abundance and distribution, body mass, and food types. Two captive groups of Japanese macaques (Macaca fuscata), one housed in a forested enclosure and the other in a nonvegetated enclosure, were studied to examine the effect of environmental enrichment on age class differences in feeding behavior. Although there was no significant age class difference in time spent feeding on provisioned foods in either enclosure, the feeding rate (intake of unit food/minute) of adults consuming provisioned monkey chow was significantly higher than that of immatures in both enclosures, and was faster for both age groups in the nonvegetated than in the forested enclosure. Overall, feeding time was greatly extended for individuals of both age classes in the forested enclosure compared with their counterparts in the nonvegetated enclosure. Immatures in the forested enclosure utilized a significantly greater number of plant species and food items, exploiting many food items available among the terminal branches, and spent significantly more time feeding than adults. Perhaps constrained by larger body size, adults fed more often on the ground or middle height of the trees, likely reducing competition over plant food resources between adults and immatures. The natural vegetation played an important role in extending feeding time and segregating substrate use during feeding by adults and immatures. This study revealed the benefits concerning environmental enrichment of a naturally forested enclosure, which provides captive primates the opportunity to exhibit age class and species-typical feeding behaviors of importance for their dietary maintenance and general health.     

Factors influencing the longitudinal distribution of larval Hydropsychidae (Trichoptera) in a southern Appalachian stream system (U.S.A.)

The influence of physical habitat variables and suspended particulate organic matter (seston) on the distribution and production of eight species of larval Hydropsychidae was studied along a 6.4 km section of a southern Appalachian stream. Samples were collected at six stations encompassing stream orders 1–4 and an elevation range of 610 m. Multivariate analysis of covariance (using time as the covariable) and discriminant function analysis were used to examine habitat differences between the sampling stations due to the following variables: current velocity; coarse benthic detritus; substrate composition (by particle size); substrate heterogeneity; degree-days; and diel temperature fluctuation. The associations of these variables with the abundance (and production) of larval hydropsychids was also examined using the same statistical procedures. The six sampling stations represented three or four distinct habitats based on patterns of change in the variables along the stream continuum. Diel temperature fluctuation, median substrate particle size, the proportion of sand substrate, and substrate heterogeneity were most closely associated with the overall difference between the sampling stations. Hydropsychid species distribution along the stream system followed subfamily lines, i.e., Arctopsychinae and Diplectroninae were more abundant and productive in the upper 4.5 km of the stream, while Hydropsychinae were dominant in the lower 1.9 km. Diel temperature fluctuation was the habitat variable most highly correlated with patterns of hydropsychid abundance and production. The longitudinal pattern of species distribution, i.e., larger particle feeding Arctopsychinae being replaced downstream by smaller particle feeding Hydropsychinae, also coincided with the distribution of seston particle size classes along the stream. Mean seston particle size generally declined downstream, as particles <42 µm increased in relative abundance while those between 43 µm and 5 mm decreased. Temperature, seston, and substrate composition all undoubtedly exerted an important influence on the distribution and production of Hydropsychidae and other filter feeding insects in this stream. The validity and generality of these results depend upon the scope of the sampling effort. Conclusions drawn from data collected over the entire range (and limits) of a species' distribution are more sound than those based on data from a limited area.     

Seasonal changes in food resource distribution and feeding sites selected by Japanese macaques on Koshima Islet,Japan

Feeding sites of Japanese macaques (Macaca fuscata) change according to seasonal fluctuations in food resource distribution. To examine what characteristics of food items affect feeding site selection, I describe herein the seasonal changes in food items, feeding sites, and food resource distributions of this species. Feeding behavior of monkeys and their food resource distributions were investigated on Koshima Islet, southern Japan, for four study periods (i.e., seasons) in 2002. Monkeys showed large variations in their diet between seasons. To weigh the relative influence of the distribution and abundance of food items on feeding site selection in each season, multiple regression analyses were performed by 100 m × 100 m grid. In the analyses, feeding time was a dependent variable and the abundance of staple food items, for which feeding time was over 5% in each season, in each grid square was an independent variable. There was no correlation between the resource distribution of most food items and the distribution of feeding time by monkeys in each season. Monkeys spent more feeding time where multiple staple food items were available. Food items that affected feeding site selection by monkeys had the following three characteristics: (1) clumped distribution, (2) seasonal availability, and (3) fruit. This suggests that monkeys are likely to select feeding sites to consume food items whose availability is limited temporally and spatially, which may enable them to simultaneously use other widely distributed, abundant food items efficiently.     

Are ball-rolling (Scarabaeini,Gymnopleurini, Sisyphini) and tunnelling scarabaeine dung beetles equally choosy about the size of ingested dung particles?

Abstract.  1. The maximum size of ingested particles was determined in 11 species of ball-rolling, adult dung beetle (Scarabaeidae: Scarabaeinae) by mixing small latex or glass balls of known diameter into their food. The tribes Scarabaeini, Gymnopleurini, and Sisyphini (four, four, and three species respectively) were represented, with mean body sizes ranging from 0.33 to 4.0 g fresh weight.
2. Only particles with maximum diameters of 4–85 µm were ingested. Hence rollers, like other known beetles feeding on fresh dung, filter out larger, indigestible plant fragments and confine ingestion to small particles of higher nutritional value.
3. The maximum diameter of ingested particles increased significantly with body weight, whereas taxon (tribe) had no additional effect. Because big rollers accept larger particles than do tunnellers (which make dung stores for feeding and breeding in the soil immediately below the pat) of similar weight, the slope of the diameter-against-weight regression for rollers was significantly higher than that found earlier for tunnellers.
4. An explanation could be that a typical food ball made by a roller is considerably smaller than the amount of dung available to a feeding tunneller of the same size. If the roller were as choosy about particle size as the tunneller, it might not get enough food. This applies to large rollers in particular because their food balls contain a higher proportion of coarse fibres than those made by small species.     

Comparative morphology of the feeding basket of five species of Euphausia (Crustacea,Euphausiacea) in the western North Pacific,with some ecological considerations

The feeding basket morphology and stomach content analyses of five Euphausia species (E. recurva, E. nana, E. pacifica, E. mutica and E. similis) were compared to elucidate their feeding ecology. The filter areas of feeding basket of E. pacifica and E. nana were proportionally larger than those of others in the size classes 13-20 mm and <13 mm, respectively, suggesting a high filtering efficiency in these species at each size class. Based on the secondary setal distance, it is suggested that there are three types of feeding basket in five Euphausia species. One is the fine mesh (<5 μm) of E. pacifica and E. nana; a second is the medium (10-20 μm) of E. recurva and E. mutica; and the third is the coarse (20-30 μm) of E. similis. The ability to feed on particles <5 μm would give both species, E. pacifica and E. nana, a great advantage over other species when number of flagellates is high. Stomach content analyses indicated a more omnivorous feeding mode in E. mutica, E. recurva and E. similis and a more herbivorous in E. pacifica and E. nana. This is in agreement with morphological studies of feeding baskets. Increments in the primary and secondary setal distances with increasing size of four Euphausia species, except E. pacifica, were evident, reflecting interspecific differences in food particle sizes utilized. In E. pacifica, however, the morphological similarity should produce intraspecific competition in diet. This revised version was published online in September 2006 with corrections to the Cover Date.     

Influence of environmental factors and individual traits on the diet of non-native hybrid bigheaded carp (Hypophthalmichthys molitrix × H. nobilis) in Lake Balaton,Hungary

Planktivorous silver carp and bighead carp (collectively, the bigheaded carps) have been stocked worldwide and their invasion has caused severe impacts on many freshwater ecosystems. Exploiting the chance provided by the specific hybrid bigheaded carp stock in Lake Balaton (Hungary) covering the entire morphological range between the two species (including gill raker morphology), we implemented a comprehensive study (1) to reveal the feeding habits of hybrid bigheaded carps living in a mesotrophic, lacustrine habitat and (2) to assess how biotic and abiotic environmental factors and gill raker morphology affect diet composition. We found that all bigheaded carps utilized primarily zooplankton and neglected the scarce and inefficiently digestible phytoplankton, irrespective of gill raker morphology. Moreover, we observed strikingly high levels of inorganic debris consumption, but the proportion of inorganic matter in the guts was not associated directly with the concentration of suspended inorganic particles. Variance in the diet composition of bigheaded carps was related mostly to environmental factors, including the wind-induced resuspension of inorganic particles and seasonally variable availability of food resources. In conclusion, the effects of abiotic environmental factors and available food resources could overwhelm the effect of gill raker morphology in shaping the feeding habits of bigheaded carps.

     

Organic coatings and ontogenetic particle selection in Streblospio benedicti Webster (Spionidae: Polychaeta)

Surface deposit feeders select food particles based upon characteristics including size, texture, specific gravity, and organic coatings. Spionid polychaetes feed at the sediment-water interface using a pair of ciliated palps and switch between surface deposit feeding and suspension feeding primarily as a function of water flow. Juveniles and adults of some spionid species have different stable isotopic carbon signals, indicating the ingestion of different food sources and potentially the ability to differentiate organic cues ontogenetically. In the present study, the feeding responses of juvenile and adult Streblospio benedicti Webster to seven organic coatings bound to glass microbeads were tested using five amino acids and two carbohydrates. Coated versus uncoated particles were presented in equal proportions based upon surface area. Juveniles and adults were highly selective for all seven types of organically coated beads—87.1% of all beads ingested were organically coated beads. For two of the organic coatings, there were ontogenetic differences; juveniles were more selective of threonine and adults were more selective of proline. These differences may result in ontogenetic diet shifts that allow maximization of energy and/or essential nutrients during critical early life-history stages. Particle selection in tentaculate surface deposit feeders is generally thought to occur primarily during particle contact and transport to the mouth, and is typically characterized as a passive process. Active particle selection at the site of the everted pharynx was observed and quantified for S. benedicti. Organically coated particles represented 50% of the ambient experimental treatment, 64.4% of the particles transported along the palp after contact, and 81.8% of the particles ingested after pharyngeal rejection behavior. Of the beads reaching the pharynx, 26.9% were rejected by ciliary sorting on the pharynx before ingestion, and 81.8% of the rejected beads at the site of the pharynx were uncoated. Our study demonstrates that microphagous feeders that generally handle food particles in bulk are capable of significant levels of active selection for organically coated particles.