Pharyngeal Basket Research Articles

Dental structure and tooth attachment modes in the common fangtooth Anoplogaster cornuta (Valenciennes, 1833) (Actinopterygii; Trachichthyiformes; Anoplogastridae).

We studied the structure and attachment modes of the teeth of adult Anoplogaster cornuta using light- and scanning-electron microscopic techniques. All teeth were monocuspid, composed solely of orthodentin, and lacked a covering enameloid cap. Fourteen teeth were present in the oral jaws, with three teeth each on the left and right premaxilla and four teeth each on the left and right dentary. The anteriormost premaxillary and dentary teeth were considerably larger than the more posteriorly located ones. The oral jaw teeth were transparent, non-depressible and firmly ankylosed to their respective dentigerous bone by a largely anosteocytic bone of attachment. No evidence for replacement of the large oral jaw teeth was found in the analyzed adult specimens. The bone of attachment exhibited lower calcium and phosphorus concentrations and a higher Ca/P ratio than the orthodentin. The connection between dentinal tooth shaft and bone of attachment was stabilized by a collar of mineralized collagen fibers. In contrast to the oral jaw teeth, the pharyngeal teeth exhibited a ring-like fibrous attachment to their supporting bones. This mode of attachment provides the teeth with some lateral mobility and allows their depression relative to their supporting bones, which may facilitate intra-pharyngeal prey transport. In contrast, a firm ankylosis was observed in numerous small teeth located on the branchial arches. The function of these teeth is presumably to increase the tightness of the pharyngeal basket and thereby the retention of small prey items in a species living in a habitat with only sparse food supply. Our findings corroborate earlier statements on the tooth attachment modes of the oral jaw teeth of Anoplogaster cornuta, but provide new findings for the attachment modes of pharyngeal teeth in this species.

New Ediacaran fossils from the Ukraine, some with a putative tunicate relationship

Sack-like body fossils Finkoella ukrainica gen. et sp. nov. and F. oblonga sp. nov., and reticulate fossil Pharyngomorpha reticulata gen. et sp. nov. are described from the upper Ediacaran shallow-marine deposits of Ukraine, which are no younger than 557 Ma. The first two resemble the flattened bodies of tunicates showing mainly the outline of tunica, while the third is considered as a fragment of the pharyngeal basket of a tunicate. F. ukrainica is represented by smaller individuals interpreted as juveniles, which may occur in clusters together with less numerous larger individuals. The larger forms are interpreted as adults, some of which show the preserved oral/atrial syphons and possible traces of internal organs bulging through the tunica. Moreover, Burykhia sp. from the uppermost Ediacaran of the same region is presented. This is the second and younger occurrence of the genus Burykhia, which is preserved as a possible fragment of the pharyngeal basket. All the fossils are preserved as the “death masks” between microbial mats, and their appearance depends partly on the relation to the parting surface on which they are observed. The presented new taxa along with the literature data reinforce the possibility that tunicates originated already in late Ediacaran.

Analyses of marine products containing a large quantity of toxic elements

In recent years, the contamination of marine products with heavy toxic elements has become a problem in Japan, as the Japanese coastal sea water is confirmed to be highly contaminated with heavy elements. In this study, parts of scallops and ascidians, which are the main foods of the people living in the Sanriku District, including hijiki and the fatty meal of whale, were analyzed. We also analyzed some parts that are not commonly eaten in general but are often consumed by some local populations, such as the mantle, mid-gut gland, ovary and spermary of scallops, and the internal organs and pharyngeal basket of ascidians. Dangerous quantities were detected for mercury in fatty meal of whale and for arsenic in hijiki, the mid-gut gland and mantle of scallops and the internal organs and pharyngeal basket of ascidians. In addition, concentrations of cadmium in the mid-gut gland and mantle of scallops as well as in the internal organs and pharyngeal basket of ascidians also showed high values. These results suggested that, even in the daily diet, it is possible to consume arsenic and cadmium in greater-than-tolerable quantities.

Multiple origins of Heliozoa from flagellate ancestors: New cryptist subphylum Corbihelia, superclass Corbistoma, and monophyly of Haptista, Cryptista, Hacrobia and Chromista

Heliozoan protists have radiating cell projections (axopodia) supported by microtubular axonemes nucleated by the centrosome and bearing granule-like extrusomes for catching prey. To clarify previously confused heliozoan phylogeny we sequenced partial transcriptomes of two tiny naked heliozoa, the endohelean Microheliella maris and centrohelid Oxnerella marina, and the cercozoan pseudoheliozoan Minimassisteria diva. Phylogenetic analysis of 187 genes confirms that all are chromists; but centrohelids (microtubules arranged as hexagons and triangles) are not sisters to Endohelea having axonemes in transnuclear cytoplasmic channels (triangular or square microtubular arrays). Centrohelids are strongly sister to haptophytes (together phylum Haptista); we explain the common origins of their axopodia and haptonema. Microheliella is sister to new superclass Corbistoma (zooflagellate Telonemea and Picomonadea, with asymmetric microfilamentous pharyngeal basket), showing that these axopodial protists evolved independently from zooflagellate ancestors. We group Corbistoma and Endohelea as new cryptist subphylum Corbihelia with dense fibrillar interorganellar connections; endohelean axopodia and Telonema cortex are ultrastructurally related. Differently sampled trees clarify why corticate multigene eukaryote phylogeny is problematic: long-branch artefacts probably distort deep multigene phylogeny of corticates (Plantae, Chromista); basal radiations may be contradictorily reconstructed because of their extreme closeness and the Bayesian star-tree paradox. Haptista and Hacrobia are holophyletic, and Chromista probably are.

The oldest cinctan carpoid (stem-group Echinodermata), and the evolution of the water vascular system

A new cinctan (Protocinctus mansillaensis gen. et sp. nov.), from the early Middle Cambrian of the Iberian Chains (north-east Spain), is described with the aid of X-ray microtomography and three-dimensional computer models. Investigation in this manner was possible because of the unusual condition of the fossils, which are preserved as recrystallized calcite. Protocinctus gen nov. possesses an elongate body with a single left anterior feeding groove and an open posterior marginal frame (in ventral view): this combination of characters is unique amongst cinctans. Through the study of original specimens and ‘virtual fossils’ it was possible to reconstruct the palaeobiology of Protocinctus gen. nov.: cinctans are interpreted as pharyngeal basket feeders with a U-shaped gut, using their posterior appendage to aid stability on the sediment surface. Cinctans are critical to understanding the evolutionary history of the echinoderm stem group, as they illustrate the transition from a paired water vascular system (basal) to one constructed from just the left hydrocoel (derived). The former condition is also observed in another group of stem-group echinoderms, the ctenocystoids, and is hypothesized for the latest common ancestor of the echinoderms and hemichordates.

The pre‐radial history of echinoderms

AbstractGene sequence data now identify a robust phylogeny of deuterostomes and provide a framework within which the evolution of echinoderms can be interpreted. The topology of the molecular tree makes a number of important predictions about the morphological characters of the earliest echinoderm at its split from hemichordates: it possessed gill slits (but not a notochord), had a bilaterally symmetrical body plan in the adult and, less certainly, underwent torsion during development. Carpoids, a highly contentious group of extinct deuterostomes with a plated calcite skeleton that have variously been interpreted as stem‐ and crown‐group chordates, stem‐group echinoderms or stem‐ and crown‐group echinoderms, display many of these basal characters and provide critical evidence for how the latest common ancestor of hemichordates and echinoderms was transformed into a pentaradiate crown‐group echinoderm.Cinctans have a large atrial opening in addition to mouth and anus, and are interpreted as pharyngeal basket feeders. The paired grooves associated with the mouth indicate the presence of a hydrovascular system, but not necessarily one built along the echinoderm plan (that is, derived from just the left hydrocoel). Stylophorans have a bilateral body plan that is externally masked by torsion and possess gills, either unpaired and external, or paired and internal, opening into an atrial cavity. Their bilateral appendage is a locomotory organ, not an ambulacrum, and there is no evidence that stylophorans ever possessed a well‐developed hydrovascular system homologous to the water vascular system of echinoderms and the tentacles of pterobranch hemichordates. Solutes are the most crownward, having a true echinodermal ambulacral system with a single hydropore and no pharyngeal gill openings. Copyright © 2005 John Wiley & Sons, Ltd.

Morphological studies on a new species of Orthodonella, with redescription of O. gutta (Cohn, 1866) Kahl, 1931 (Protozoa: Ciliophora: Synhymeniida) from coastal water off Qingdao, China

The morphology and infraciliature of two marine synhymeniid ciliates, Orthodonella apohamatus nov. spec. and Orthodonella gutta (Cohn, 1866) Kahl, 1931, collected from coastal water off Qingdao, China, were studied on living cells and using protargol silver impregnation. The diagnosis for O. apohamatus nov. spec.: marine Orthodonella with length×width about 60–160×20–35 µm in vivo; lanceolate body shape with conspicuous beak-like projection at anterior end; 42–60 (mean 53) somatic kineties, including 28–42 on ventral and 13–20 on dorsal side; synhymenium with about 54–62 dikinetids; pharyngeal basket composed of 8–13 rods; four contractile vacuoles, two in middle near left margin and two at posterior end of cell; one elongated macronucleus and one micronucleus. Based on a Qingdao population, an improved diagnosis for the poorly known species, O. gutta is suggested: marine Orthodonella in vivo about 140–200×60–100 µm; body widely ellipsoidal with contractile beak-like anterior end; 62–74 (mean 66) somatic kineties with ca 41–48 ventral and 20–26 dorsal; synhymenium consisting of 43–70 dikinetids; 11–14 pharyngeal rods; one to several contractile vacuoles distributed in caudal area of cell; numerous cortical granules tiny and colourless; one ovoid macronucleus.

Metamorphosis in the anadromous sea lamprey, Petromyzon marinus L.

A study has been made of metamorphosis in anadromous sea lampreys in New Brunswick between 1973 and 1976. The stages (1–7) commence with the recently described 'prometamorphic ammocoete' (Youson, J. H., G. M. Wright, and E. C. Ooi. 1977. The timing of changes in several internal organs during metamorphosis of anadromous larval lamprey Petromyzon marinus L. Can. J. Zool. 55: 469–473.) and conclude with one similar to the newly metamorphosed landlocked sea lamprey (Manion, P. J., and T. M. Stauffer. 1970. Metamorphosis of the landlocked sea lamprey, Petromyzon marinus. J. Fish. Res. Board Can. 27: 1735–1746.). Most of the marked quantitative changes exhibited by certain regions of the body can be directly related to adaptations for suctorial feeding, increased activity, and a predaceous mode of life. Reductions in the prebranchial length are almost certainly associated with changes in the pharyngeal basket which facilitate alterations in the direction of the respiratory water flow. The timing of metamorphosis was remarkably synchronous both within and between years, representatives of the earliest stages (1–2) being found only between July 7 and 28 while after September 14 only stage 7 animals were caught. During metamorphosis the lengths of the animals changed little whereas their weights declined significantly. The weights and condition factors of stage 1–2 animals were significantly greater than those of larvae of comparable length. This feature, presumably related to lipid accumulation at the end of larval life, is discussed in the context of factors influencing the onset of metamorphosis.

Mouth size and predator strategy of midwater fishes

It has been suggested that bathypelagic fishes should be equipped to eat any large or small food item that they should chance to meet in their relatively impoverished environment. The derived hypothesis that bathypelagic species are trophically generalized was indirectly substantiated in two taxonomic groups of midwater fishes. Bathypelagic members tend to be larger and have larger mouths than their mesopelagic relatives, but still have a well-developed pharyngeal basket for retaining small items. Bathypelagic offshoots of the primarily mesopelagic group of lanternfishes seem to have acquired larger mouths at the presumed metabolic expense of having proportionately larger bodies. The deeper-living members of the primarily lower mesopelagic or bathypelagic family Melamphaidae are further specialized in that they have disproportionately larger mouths with minimum additional body size. This discussed relative to theoretical considerations of foraging strategy and metabolic economy.

Fine Structure of the Oral Apparatus of the Gymnostome Ciliate Chlamydodon pedarius

SYNOPSIS. The oral apparatus of the gymnostome ciliate Chlamydodon pedarius is composed of a membranous system, a pharyngeal basket and pharyngeal tube. The membranous system outlines the cytostome; its outer part is connected with the pellicular and sub‐pellicular membranes, forming a circular groove along the outer margin of the cytostome; its inner part bends and extends to the cytopharynx, forming an oral cavity. The membranous system consists of a membrane combining the pellicular and sub‐pellicular membranes and just beneath it is a layer of randomly intertwining filaments about 20 mμ in diameter. The pharyngeal basket is composed of triangular trichites and long ones. They are normally 11 to 13 in number. The triangular trichites are connected with the long ones by fibers. Each of the triangular trichites has a quasi‐conical form, about 1.5 μ in width at its basal portion and about 2.5 μ in height, and is made up of an outer dense sheath and a central less dense part. Each of the long trichites is whip‐shaped and extends into the endoplasm for about 35 μ. They surround the pharyngeal tube, and their posterior ends are gathered into a triangular or a circular form by means of a fiber. Each of the long trichites consists of a bundle of about 700 filaments arranged in an almost hexagonal pattern. Each filament is about 20 mμ in diameter and seems to be linked with others by six fine fibrils. The pharyngeal tube is composed of lamellae about a hundred in number. The lamellae are about 30 mμ in thickness and about 40 mμ apart from each other. The substance of the lamellae appears to be largely‐structureless, although some very fine, short fibrils randomly arranged can be distinguished in longitudinal sections.It is concluded that the component parts of the oral apparatus may come from different origins. Each of the long trichites composing the pharyngeal basket may originate from about 80 kinetosomes, and the lamellae composing the pharyngeal tube and the membranous system may arise from the sub‐pellicular membrane.

Phase Contrast Microscopy of Cytoplasmic Organelles in the Gymnostome Ciliate Chlamydodon pedarins

SYNOPSIS.Chlamydodon pedarius has peculiar and interesting cytoplasmic organelles, such as the pharyngeal basket and the cross‐striped band, and exhibits plasmotomy of an uncommon type at the division stage. For comparison of the results of observations on fixed and stained material and on living material examined with phase contrast, and because of finding important differences in such a comparison, this morphological study of the cytoplasmic organelles was undertaken.The cilia, arranged in about forty rows only on the ventral surface, the anterior part of which shifts out of the dorsal body, bending to the dorsal side, are almost the same everywhere, about 5 μ in length. The cross‐striped band, encircling the body surface so as to divide it into dorsal and ventral parts, has the power of movement, such as folding of the semicircular trichites and closing or opening of them. The oral apparatus, composed of a membranous system and a pharyngeal basket, is an elaborate organelle. The membranous system shows such movement as seen in a sphincter muscle, moving the triangular trichites in a manner which opens or closes the cytostome. Each of the triangular trichites is con nected with the expanded end of a long trichite; together these structures. 11–13 in number, constitute the pharyngeal basket. The ridges, the long trichites and the semicircular trichites are composed of fibrillar elements, but their twisted figures may be produced artificially by staining methods.Binary fission of Chlamydodon pedarius, under natural conditions in the season from April to October, occurs daily during the period 11 a.m. to 4 p.m. Each of the fissions takes about 2 hours. In the first half of this fission time: the V‐area consisting of four central ciliary systems gives rise to transitions in the arrangement of the ciliary rows and ridges on both its anterior and middle portions; the pharyngeal basket falls down into the cytoplasm; and rosettes appear in the above two fields. On the other hand, plasmotomy arises in a fission furrow from the right side of the fission line. In the second half of the fission process, the oral apparatuses develop from the rosettes, while the old basket is dissolved into the cytoplasm; and, as the fission furrow extends leftward, two transverse bands and the frontal pellicle of the posterior daughter ciliate are organized on the surface of the fission furrow.

Homalozoon vermiculare (Stokes): I. Morphology and Reproduction*

SUMMARY. Homalozoon vermiculare (Stokes) is a vermiform holotrichous ciliate of the family Spathidiidae. Its functional ventral side bears 12 longitudinal rows of short cilia. The functionally dorsal side bears a prominent longitudinal ridge, is devoid of cilia, and has very fine pellicular striations. The nuclear apparatus consists of a long folded moniliform macronucleus and several small spherical micronuclei. The contractile vacuoles are variable in number and form a longitudinal row along the functionally right side of the organism.The organism varies from 150 μ to 1500 μ in length and 35 μ to 45 μ in width in its relaxed state. It is highly contractile and its movement resembles that of a turbellarian. The body can be divided into three regions: neck, trunk, and caudal region. The neck region has a cytostome at the anterior end surrounded by a pharyngeal basket and a pair of conspicuous parapharyngeal granular masses at the posterior end. The trunk region is very granular and contains the contractile vacuoles and nuclear apparatus. The caudal region is hyaline and often contains trichite bundles. Free floating trichites are found throughout the organism.Two types of reproduction have been observed. The first type is transverse fission during which the macronucleus separates into two lengths, a new pharyngeal basket forms posterior to the division constriction, and parapharyngeal granular masses develop posterior to the new pharyngeal basket. In the second type of division the cytoplasm condenses in the anterior end of the animal leaving the posterior end very flaccid. The macronucleus then undergoes extensive reorganization followed by the development of a daughter cell from the flaccid posterior region. A new flaccid posterior region grows out of the anterior mass after separation of the first daughter cell and the division process is repeated several times until the remaining portion of the anterior mass disintegrates.

Cytological Observations on Gymnostomatous Ciliates, with a Description of the Maturation Phenomena in Diploid and Tetraploid Forms of Chilodon uncinatus

ABSTRACT Some form of supporting structure is found around the oral opening in many species of ciliates. This varies from a few trichites around the mouth, as in Spathidium spathula, or a simple tube of trichites, as in Prorodonteres, to the very complicated apparatus found in various species of Chilodon and Nassu1a. The early investigators designated this structure the pharyngeal basket or ‘Reusenapparat ‘. There are many references to this organelle, either of a descriptive or speculative nature, particularly as to its function. Kent (1881) gives a partial account of its behaviour in division and encystment, and there is an incomplete account by Enriques (1908) of its behaviour in division and conjugation. It seems desirable, therefore, to make an extended study of the structure in order to determine its origin, if possible, and its behaviour in the complete life-cycle. This naturally led to a study of the basket during division, conjugation, and encystment phases, and the material obtained for this purpose was found to be favourable for the further study of nuclei during division and conjugation.