Food gathering

SUMMARY The mode of feeding in Amphioxus is effected by– (1) The maintenance of a stream of water through the pharynx by rows of lateral cilia on the gill-bars. (2) The throwing out of mucus from the endostyle on to the gill-bars to serve for entrapping food-particles. (3) The collection of food-particles by rows of cilia on the pharyngeal surface of the gill-bars; these cilia woraSkip the foodparticles with mucus into cylindrical masses and transport such masses dorsally into the dorsal groove which carries the collected masses backwards into the digestive tract. Thus the ciliary mechanisms on a gill-bar of Amphioxus are exactly the same as those on the gill-filaments of some Lamellibranchs, as Pecten, and some Gastropods, as Crepidula. A subsidiary mode of food-collection is effected in the buccal cavity of Amphioxus by the ciliated tract known as the wheel organ, and Hatchek's pit, which supplies mucus for entrapping food-particles. These particles are passed on to the peri-pharyngeal bands which, conduct them in turn into the dorsal groove. The gill of Amphioxus functions mainly as a feeding organ and a water pump, and probably not at all as an organ for aerating the blood. The mode of feeding in Ascidians is almost exactly the same as that described above for Amphioxus. Food-collection, however, in Ascidians is effected by cilia on the papillae and similar outgrowths on the gill, and is also helped in some forms by transverse waving of the longitudinal bars, by which process the food is pushed as well as lashed towards the dorsal region of the pharynx.

@article{orton1913the,
    author = "Orton, J. H.",
    title = "The Ciliary Mechanisms on the Gill and the Mode of Feeding in Amphioxus, Ascidians, and Solenomya togata",
    year = "1913",
    journal = "Journal of the Marine Biological Association of the United Kingdom",
    abstract = "SUMMARY The mode of feeding in Amphioxus is effected by– (1) The maintenance of a stream of water through the pharynx by rows of lateral cilia on the gill-bars. (2) The throwing out of mucus from the endostyle on to the gill-bars to serve for entrapping food-particles. (3) The collection of food-particles by rows of cilia on the pharyngeal surface of the gill-bars; these cilia woraSkip the foodparticles with mucus into cylindrical masses and transport such masses dorsally into the dorsal groove which carries the collected masses backwards into the digestive tract. Thus the ciliary mechanisms on a gill-bar of Amphioxus are exactly the same as those on the gill-filaments of some Lamellibranchs, as Pecten, and some Gastropods, as Crepidula. A subsidiary mode of food-collection is effected in the buccal cavity of Amphioxus by the ciliated tract known as the wheel organ, and Hatchek's pit, which supplies mucus for entrapping food-particles. These particles are passed on to the peri-pharyngeal bands which, conduct them in turn into the dorsal groove. The gill of Amphioxus functions mainly as a feeding organ and a water pump, and probably not at all as an organ for aerating the blood. The mode of feeding in Ascidians is almost exactly the same as that described above for Amphioxus. Food-collection, however, in Ascidians is effected by cilia on the papillae and similar outgrowths on the gill, and is also helped in some forms by transverse waving of the longitudinal bars, by which process the food is pushed as well as lashed towards the dorsal region of the pharynx.",
    url = "https://doi.org/10.1017/s0025315400006706",
    doi = "10.1017/s0025315400006706",
    number = "1",
    openalex = "W2036476667",
    pages = "19-49",
    volume = "10"
}

@article{orton1913the2,
    author = "Orton, J. H",
    title = "The ciliary mechanisms on the gill and the mode of feeding in Amphioxus, Ascidians and Solenomyo togato",
    year = "1913",
    journal = "Journal of the Marine Biological Association of the United Kingdom, v. 10, p. 19-49",
    note = "talkorigins\_source = {true}; raw\_reference = {Orton, J. H., 1913, The ciliary mechanisms on the gill and the mode of feeding in Amphioxus, Ascidians and Solenomyo togato: Journal of the Marine Biological Association of the United Kingdom, v. 10, p. 19-49.}"
}

Abstract The cilia lining the stigmata of the branchial sac of an ascidian circulate water through the animal. These stigmatal cilia are under nervous control; when either siphon is stimulated, both siphons close by muscular contractions and at the same time the stigmatal cilia stop beating simultaneously in all parts of the branchial sac. Spontaneous ciliary arrests may also occur, with or without associated closure of the siphons. Elements of the branchial nervous system that run in the gill bars are assumed to be concerned in coordination of the ciliary arrests. The majority of the branchial nerve fibres emerge dorsally from the visceral nerves that form the posterior brain roots, although nerves are also believed to enter the branchial sac along its anterior margin. No cell bodies could be found in the branchial nerves or in the visceral nerves, so that the cell bodies of the branchial nerve fibres are assumed to lie in the central nervous system. The branchial nerve fibres form a peripheral conducting net extending throughout the branchial sac. Branches of these nerve fibres terminate in contact with some of the ciliated cells; cell-to-cell conduction (through close junctions?) probably spreads excitation to the other ciliated cells. Nerve-nerve junctions appear to be more sensitive to curare than those between nerves and ciliated cells. Electrical recordings from the branchial sac, obtained with suction electrodes, show that arrest of the cilia is accompanied by electrical activity, and that prolonged arrest is maintained by trains of regular pulses. Intracellular microelectrodes in the ciliated cells indicate that these cells have a negative resting potential of 30-40 mV, and that a ciliary arrest is associated with a positive-going spike of 45-50 mV. The externally recorded ‘ciliary arrest potentials’ probably represent the coordinated depolarization of many ciliated cells. The rhythmical character of the trains of pulses presumably depends on pacemaker activity; this is not localized, since intact organisms or isolated small portions of the branchial sac are capable of generating similar trains of pulses. During the arrest response the stigmatal cilia first perform a reverse beat, then maintain the reverse position for several seconds before slowly relaxing and after several more seconds recommencing to beat with progressively increasing amplitude. The duration of the arrest response varies in media with different concentrations of the common cations, and also varies in response to repetitive stimulation, in a manner which suggests that the depolarization of the ciliated cells is associated with an influx of Ca2+, so that the ciliary control here may have some close parallels with that described for Paramecium.

@article{doi101098rspb19740058,
    author = "Mackie, G. O. and Paul, D. H. and Singla, C. M. and Sleigh, M. A. and Williams, Daphne",
    title = "Branchial innervation and ciliary control in the ascidian Corella",
    year = "1974",
    journal = "Proceedings of the Royal Society of London. Series B, Biological sciences",
    abstract = "Abstract The cilia lining the stigmata of the branchial sac of an ascidian circulate water through the animal. These stigmatal cilia are under nervous control; when either siphon is stimulated, both siphons close by muscular contractions and at the same time the stigmatal cilia stop beating simultaneously in all parts of the branchial sac. Spontaneous ciliary arrests may also occur, with or without associated closure of the siphons. Elements of the branchial nervous system that run in the gill bars are assumed to be concerned in coordination of the ciliary arrests. The majority of the branchial nerve fibres emerge dorsally from the visceral nerves that form the posterior brain roots, although nerves are also believed to enter the branchial sac along its anterior margin. No cell bodies could be found in the branchial nerves or in the visceral nerves, so that the cell bodies of the branchial nerve fibres are assumed to lie in the central nervous system. The branchial nerve fibres form a peripheral conducting net extending throughout the branchial sac. Branches of these nerve fibres terminate in contact with some of the ciliated cells; cell-to-cell conduction (through close junctions?) probably spreads excitation to the other ciliated cells. Nerve-nerve junctions appear to be more sensitive to curare than those between nerves and ciliated cells. Electrical recordings from the branchial sac, obtained with suction electrodes, show that arrest of the cilia is accompanied by electrical activity, and that prolonged arrest is maintained by trains of regular pulses. Intracellular microelectrodes in the ciliated cells indicate that these cells have a negative resting potential of 30-40 mV, and that a ciliary arrest is associated with a positive-going spike of 45-50 mV. The externally recorded ‘ciliary arrest potentials’ probably represent the coordinated depolarization of many ciliated cells. The rhythmical character of the trains of pulses presumably depends on pacemaker activity; this is not localized, since intact organisms or isolated small portions of the branchial sac are capable of generating similar trains of pulses. During the arrest response the stigmatal cilia first perform a reverse beat, then maintain the reverse position for several seconds before slowly relaxing and after several more seconds recommencing to beat with progressively increasing amplitude. The duration of the arrest response varies in media with different concentrations of the common cations, and also varies in response to repetitive stimulation, in a manner which suggests that the depolarization of the ciliated cells is associated with an influx of Ca2+, so that the ciliary control here may have some close parallels with that described for Paramecium.",
    url = "https://doi.org/10.1098/rspb.1974.0058",
    doi = "10.1098/rspb.1974.0058",
    openalex = "W1982720788",
    references = "doi101017s002531540001170x"
}

Observations using SCUBA reveal that macroscopic organic aggregates produced by appendicularians reached densities of 44 to 1,130 m −3 in the Gulf of California. Though these aggregates constituted less than 5% of total particulate carbon, their carbon: nitrogen ratio was twice that of particles in the surrounding seawater. The C: N ratio of the total particulate matter increased directly with the density of appendicularian produced aggregates. Aggregates were utilized extensively as food by euphausiid larvae, copepods, and planktivorous fish. Such aggregates affect the adaptive strategies and distribution of the plankton by introducing spatial heterogeneity and physical structure into an environment previously considered unstructured and may substantially alter the chemical composition of particulate organic matter.

@article{doi104319lo19762110014,
    author = "Alldredge, Alice L.",
    title = "Discarded appendicularian houses as sources of food, surface habitats, and particulate organic matter in planktonic environments",
    year = "1976",
    journal = "Limnology and Oceanography",
    abstract = "Observations using SCUBA reveal that macroscopic organic aggregates produced by appendicularians reached densities of 44 to 1,130 m −3 in the Gulf of California. Though these aggregates constituted less than 5\% of total particulate carbon, their carbon: nitrogen ratio was twice that of particles in the surrounding seawater. The C: N ratio of the total particulate matter increased directly with the density of appendicularian produced aggregates. Aggregates were utilized extensively as food by euphausiid larvae, copepods, and planktivorous fish. Such aggregates affect the adaptive strategies and distribution of the plankton by introducing spatial heterogeneity and physical structure into an environment previously considered unstructured and may substantially alter the chemical composition of particulate organic matter.",
    url = "https://doi.org/10.4319/lo.1976.21.1.0014",
    doi = "10.4319/lo.1976.21.1.0014",
    openalex = "W2156426192"
}

@article{flood1978filter,
    author = "Flood, P. R.",
    title = "Filter characteristics of appendicularian food catching nets",
    year = "1978",
    journal = "Experientia",
    url = "https://doi.org/10.1007/bf01944659",
    doi = "10.1007/bf01944659",
    number = "2",
    openalex = "W1995033830",
    pages = "173-175",
    volume = "34",
    references = "doi101007bf00391483, doi1010160011747176909189, doi1023072965, doi1023073225307"
}

@misc{flood1978filter1,
    author = "Flood, P. R",
    title = "Filter characteristics of appendicularian food catching nets",
    year = "1978",
    howpublished = "Experientia, v. 34, p. 173-175",
    note = "talkorigins\_source = {true}; raw\_reference = {Flood, P. R., 1978, Filter characteristics of appendicularian food catching nets: Experientia, v. 34, p. 173-175.}"
}

Transmission and scanning electron microscopy of food trapping filters or “mucous films” of several Ascidians reveal the same type of extensive net with elongate rectangular meshes. The ultrastructural appearance and mesh size varies only slightly within the group. Pore sizes from 0.2 to 0.5 μm in width and from 0.5 to 2.2 μm in length with a thickness of the filaments from 10 to 40 nm are probably representative for the nets under in vivo conditions. These observations corroborate earlier experimental results which indicate a remarkably high and constant efficiency of filtration in all species kept undisturbed. Great quantities of water are evidently filtered through these nets at relatively low resistance and particles even below bacterial size (0.5 μm) are effectively trapped. Histochemical reactions indicate the presence of both mucoproteins and acidic polysaccharide components and that the filaments are probably made up of a peptide core surrounded by polysaccharides.

@article{doi101111j146363951981tb00616x,
    author = "Flood, Per R. and Fiala‐Médioni, Aline",
    title = "Ultrastructure and Histochemistry of the Food Trapping Mucous Film in Benthic Filter-Feeders (Ascidians)",
    year = "1981",
    journal = "Acta Zoologica",
    abstract = "Transmission and scanning electron microscopy of food trapping filters or “mucous films” of several Ascidians reveal the same type of extensive net with elongate rectangular meshes. The ultrastructural appearance and mesh size varies only slightly within the group. Pore sizes from 0.2 to 0.5 μm in width and from 0.5 to 2.2 μm in length with a thickness of the filaments from 10 to 40 nm are probably representative for the nets under in vivo conditions. These observations corroborate earlier experimental results which indicate a remarkably high and constant efficiency of filtration in all species kept undisturbed. Great quantities of water are evidently filtered through these nets at relatively low resistance and particles even below bacterial size (0.5 μm) are effectively trapped. Histochemical reactions indicate the presence of both mucoproteins and acidic polysaccharide components and that the filaments are probably made up of a peptide core surrounded by polysaccharides.",
    url = "https://doi.org/10.1111/j.1463-6395.1981.tb00616.x",
    doi = "10.1111/j.1463-6395.1981.tb00616.x",
    openalex = "W2091970060",
    references = "doi101007bf00397151, doi1010160011747176909189, doi101017s0025315400017021, doi101083jcb171208, doi101086399023, doi101111j1469185x1955tb01546x, doi1023072879, doi103354meps001055, doi104319lo19762110014, openalexw655705066, orton1913the"
}

The filtering rates of Oikopleura dioica and Stegasoma magnum (Tunicata: Appendicularia) were measured in situ by a SCUBA diver in the Gulf of California. Simultaneous measurement of the age class structure of each appendicularian population, natural food densities, and the rate of increase of food particles allowed calculation of the grazing impact of each population on natural food assemblages in the field. Filtering rates increased exponentially with animal size and reached maxima of 12.5 ml·animal −1 ·h −1 for O. dioica and 627 for S. magnum. The filtering rate of S. magnum was an order of magnitude higher than that of copepods of similar ash‐free dry weight. At densities ranging from 205 to 4,587 animals·m −3, O. dioica populations filtered from 1.3 to 37.7% of each cubic meter in 24 h. At maximum population densities clearance exceeded the replacement rate of the particulate food. Stegasoma magnum ranged from 11 to 63 animals·m −3 and filtered from 5.4 to 13.4% of each cubic meter in 24 h. Direct field evidence indicates that appendicularian grazers exert significant grazing pressure on natural food assemblages in situ.

@article{doi104319lo19812620247,
    author = "Alldredge, Alice L.",
    title = "The impact of appendicularian grazing on natural food concentrations in situ1",
    year = "1981",
    journal = "Limnology and Oceanography",
    abstract = "The filtering rates of Oikopleura dioica and Stegasoma magnum (Tunicata: Appendicularia) were measured in situ by a SCUBA diver in the Gulf of California. Simultaneous measurement of the age class structure of each appendicularian population, natural food densities, and the rate of increase of food particles allowed calculation of the grazing impact of each population on natural food assemblages in the field. Filtering rates increased exponentially with animal size and reached maxima of 12.5 ml·animal −1 ·h −1 for O. dioica and 627 for S. magnum. The filtering rate of S. magnum was an order of magnitude higher than that of copepods of similar ash‐free dry weight. At densities ranging from 205 to 4,587 animals·m −3, O. dioica populations filtered from 1.3 to 37.7\% of each cubic meter in 24 h. At maximum population densities clearance exceeded the replacement rate of the particulate food. Stegasoma magnum ranged from 11 to 63 animals·m −3 and filtered from 5.4 to 13.4\% of each cubic meter in 24 h. Direct field evidence indicates that appendicularian grazers exert significant grazing pressure on natural food assemblages in situ.",
    url = "https://doi.org/10.4319/lo.1981.26.2.0247",
    doi = "10.4319/lo.1981.26.2.0247",
    openalex = "W2115134910",
    references = "alldredge1976field, doi101007bf00360952, doi101007bf00391483, doi1010160022098176900770, doi101017s0025315400018956, doi101093icb81107, doi101111j146979981977tb03236x, doi104319lo19671230492, doi104319lo19721730494, doi104319lo19741960984, doi104319lo19762150724, doi104319lo19812620247, flood1978filter"
}

Filter characteristics have been determined and compared in ciliary and mucus-net filter feeders. The ciliary feeders include the polychaete Sabella penicillus, the brachiopod Terebratulina retuso, the marine bivalves Monia squama, Cardiurn glaucum, and Petricola pholadiformis, and the freshwater bivalves Dreissena polymorpha, Unio pictamrn, and Anodonta cygnea. The mucus-net feeders are the polychaete Chaetopterus variopedatus, the gastropod Crepidula fomicata, and the ascidians Sfyela clava, Ciona intestinalis, Ascidia virginia, Ascidia obliqua, and Ascidia mentula. Efficiencies of particle retention as a function of particle size was determined by counting of particles in samples of inhalant and exhalant water. The lower threshold for efficient particle retention varied from about 6 p m in T. retuso to about 1 p n in D. polyrnorpha. Mucus nets efficiently retained particles down to 1 to 2 pm. Filter feeding is characterized by processing of water at low pressures (5 l mm H,O). Mechanisms of water processing and particle retention in brachiopods and bivalves are compared. It is concluded that laminar flow of through-currents and surface-currents in brachiopods is consistent with the hypothesis of capture of suspended particles by means of viscous forces acting upon the particles in the zone of contact between the 2 flow systems.

@article{doi103354meps015283,
    author = "Jørgensen, CB and Kørboe, T and Møhlenberg, F and Riisgård, Hans Ulrik",
    title = "Ciliary and mucus-net filter feeding, with special reference to fluid mechanical Characteristics",
    year = "1984",
    journal = "Marine Ecology Progress Series",
    abstract = "Filter characteristics have been determined and compared in ciliary and mucus-net filter feeders. The ciliary feeders include the polychaete Sabella penicillus, the brachiopod Terebratulina retuso, the marine bivalves Monia squama, Cardiurn glaucum, and Petricola pholadiformis, and the freshwater bivalves Dreissena polymorpha, Unio pictamrn, and Anodonta cygnea. The mucus-net feeders are the polychaete Chaetopterus variopedatus, the gastropod Crepidula fomicata, and the ascidians Sfyela clava, Ciona intestinalis, Ascidia virginia, Ascidia obliqua, and Ascidia mentula. Efficiencies of particle retention as a function of particle size was determined by counting of particles in samples of inhalant and exhalant water. The lower threshold for efficient particle retention varied from about 6 p m in T. retuso to about 1 p n in D. polyrnorpha. Mucus nets efficiently retained particles down to 1 to 2 pm. Filter feeding is characterized by processing of water at low pressures (5 l mm H,O). Mechanisms of water processing and particle retention in brachiopods and bivalves are compared. It is concluded that laminar flow of through-currents and surface-currents in brachiopods is consistent with the hypothesis of capture of suspended particles by means of viscous forces acting upon the particles in the zone of contact between the 2 flow systems.",
    url = "https://doi.org/10.3354/meps015283",
    doi = "10.3354/meps015283",
    openalex = "W1971107871",
    references = "doi101007bf00386593, doi1010160022098171900542, doi101016s0003936580800091, doi10108000785326197810425487, doi101111j109636421962tb01626x, doi101111j146363951981tb00616x, doi101128aem335122512281977, doi103354meps001055, doi103354meps005291, doi103354meps011089, doi104319lo19812661062, openalexw1549886310"
}

@article{berrill1987early,
    author = "Berrill, N. J.",
    title = "Early Chordate Evolution Part 2. Amphioxus and Ascidians To Settle or Not to Settle",
    year = "1987",
    journal = "International Journal of Invertebrate Reproduction and Development",
    url = "https://doi.org/10.1080/01688170.1987.10510264",
    doi = "10.1080/01688170.1987.10510264",
    number = "1",
    openalex = "W2065842809",
    pages = "15-27",
    volume = "11",
    references = "doi101002jmor1050540103, doi101002jmor1050570204, doi101007bf00232284, doi101086413055, doi101098rstb19350013, doi101098rstb19580007, doi101111j1469185x1983tb00379x, doi101111j146979981973tb01381x, doi104319lo1959420181, openalexw1567612426"
}

@article{martinucci1987a,
    author = "Martinucci, G.B. and Dallai, R. and Burighel, P.",
    title = "A comparative study of ciliary differentiations in the branchial stigmata of ascidians",
    year = "1987",
    journal = "Tissue and Cell",
    url = "https://doi.org/10.1016/0040-8166(87)90010-3",
    doi = "10.1016/0040-8166(87)90010-3",
    number = "2",
    openalex = "W1968396852",
    pages = "251-263",
    volume = "19",
    references = "doi1010160040816683900198, doi1010160303264781900460, doi101016s0065288108604575, doi101016s0074769608611936, doi101083jcb782451, doi101098rspb19740058, doi101242jcs133687, doi101242jcs6811, doi101242jcs8411, doi1023073226119"
}

@article{stokes1995ciliary,
    author = "Stokes, M. D. and Holland, N. D.",
    title = "Ciliary Hovering in Larval Lancelets (=Amphioxus)",
    year = "1995",
    journal = "The Biological Bulletin",
    url = "https://doi.org/10.2307/1542300",
    doi = "10.2307/1542300",
    number = "3",
    openalex = "W2121451173",
    pages = "231-233",
    volume = "188",
    references = "doi101017s002211207000215x, doi101038044202a0, doi1010381841849a0, doi101098rstb19940059, doi101111j146363951995tb00986x, doi101111j1469185x1989tb00471x, doi101242jcss254215279, doi101242jcss27228551, openalexw1482353918, openalexw20166170"
}

@incollection{logie2006reactive,
    author = "Logie, Robert and Hall, Jon G. and Waugh, Kevin G.",
    title = "Reactive Food Gathering",
    year = "2006",
    booktitle = "Lecture Notes in Computer Science",
    url = "https://doi.org/10.1007/11750734\_24",
    doi = "10.1007/11750734\_24",
    openalex = "W1812349136",
    pages = "406-413",
    references = "doi1010160165489694900051, doi101023a1010090405266, doi101023a1026176900459, doi10109301951346130010001, doi101093oso97801951315810010001, doi101093oso97801985345320030001, doi101093oso97801985374650010001, doi101109iat20031241092, doi1043249780203783221, doi107551mitpress58030010001"
}

@incollection{gonzaleziii2009gathering,
    author = "Gonzalez III, Joaquin Jay",
    title = "Gathering Souls with Food",
    year = "2009",
    booktitle = "Filipino American Faith in Action",
    url = "https://doi.org/10.18574/nyu/9780814731963.003.0004",
    doi = "10.18574/nyu/9780814731963.003.0004",
    openalex = "W2497778778",
    pages = "82-99"
}

@incollection{crossref2013foodgathering,
    title = "FOOD-GATHERING ECONOMIES",
    year = "2013",
    booktitle = "Habitat, Economy and Society",
    url = "https://doi.org/10.4324/9781315017440-26",
    doi = "10.4324/9781315017440-26",
    openalex = "W4244201684",
    pages = "391-397"
}

@incollection{candiani2015detection,
    author = "Candiani, Simona and Garbarino, Greta and Pestarino, Mario",
    title = "Detection of mRNA and microRNA Expression in Basal Chordates, Amphioxus and Ascidians",
    year = "2015",
    booktitle = "Neuromethods",
    url = "https://doi.org/10.1007/978-1-4939-2303-8\_14",
    doi = "10.1007/978-1-4939-2303-8\_14",
    openalex = "W2478715418",
    pages = "279-292",
    references = "doi101002dvdy20847, doi101002dvdy20956, doi101016016895259090008t, doi101016jydbio200703009, doi101038nature02871, doi101038nature07415, doi101038nmeth843, doi101111j1525142x201000452x, doi101126science1064921, doi101126science1114519"
}

@incollection{santhanam2025ascidians,
    author = "Santhanam, Ramasamy",
    title = "Ascidians As a Human Food Source",
    year = "2025",
    booktitle = "Biotechnological Potential of Ascidians",
    url = "https://doi.org/10.1201/9781003637127-3",
    doi = "10.1201/9781003637127-3",
    openalex = "W4410862283",
    pages = "25-64"
}