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Feeding Apparatus (feeding + apparatus)
Selected AbstractsULTRASTRUCTURE OF THE BASAL BODY COMPLEX AND PUTATIVE VESTIGIAL FEEDING APPARATUS IN PHACUS PLEURONECTES (EUGLENOPHYCEAE)JOURNAL OF PHYCOLOGY, Issue 2001Article first published online: 24 SEP 200 Shin, W.1, Boo, S. M.2, & Triemer, R. E.1 1Department of Life Science, Rutgers University, Piscataway, New Jersey 08854, USA; 2Department of Biology, Chungnam National University, Daejon 305-764, Korea Phacus pleuronectes (O. F. Müller) Dujardin is a phototrophic euglenoid with small discoid chloroplasts, a flat, rigid body, and longitudinally arranged pellicular strips. The flagellar apparatus consisted of two basal bodies and three flagellar roots typical of many phototrophic euglenoids, but also had a large striated fiber that connected the two basal bodies and associated with the ventral root. The three roots, in combination with the dorsal microtubular band, extended anteriorly and formed the major cytoskeletal elements supporting the reservoir membrane and ultimately the pellicle. A cytoplasmic pocket arose in the reservoir/canal transition region. It was supported by the ventral root and a C-shaped band of electron-opaque material that lined the cytoplasmic side of the pocket. A large striated fiber extended from this C-shaped band toward the reservoir membrane. The presence of striated fibers in the basal apparatus and associated with the microtubule reinforced pocket suggested that P. pleuronectes may be at the base of the Phacus lineage and may be more closely related to the phagotrophic euglenoids than to Phacus species which are ovoid in shape and have thicker pellicle strips. [source] Relating the ontogeny of functional morphology and prey selection with larval mortality in Amphiprion frenatusJOURNAL OF MORPHOLOGY, Issue 6 2010Justin Anto Abstract Survival during the pelagic larval phase of marine fish is highly variable and is subject to numerous factors. A sharp decline in the number of surviving larvae usually occurs during the transition from endogenous to exogenous feeding known as the first feeding stage in fish larvae. The present study was designed to evaluate the link between functional morphology and prey selection in an attempt to understand how the relationship influences mortality of a marine fish larva, Amphiprion frenatus, through ontogeny. Larvae were reared from hatch to 14 days post hatch (DPH) with one of four diets [rotifers and newly hatched Artemia sp. nauplii (RA); rotifers and wild plankton (RP); rotifers, wild plankton, and newly hatched Artemia nauplii (RPA); wild plankton and newly hatched Artemia nauplii (PA)]. Survival did not differ among diets. Larvae from all diets experienced mass mortality from 1 to 5 DPH followed by decreased mortality from 6 to 14 DPH; individuals fed RA were the exception, exhibiting continuous mortality from 6 to 14 DPH. Larvae consumed progressively larger prey with growth and age, likely due to age related increase in gape. During the mass mortality event, larvae selected small prey items and exhibited few ossified elements. Cessation of mass mortality coincided with consumption of large prey and ossification of key elements of the feeding apparatus. Mass mortality did not appear to be solely influenced by inability to establish first feeding. We hypothesize the interaction of reduced feeding capacities (i.e., complexity of the feeding apparatus) and larval physiology such as digestion or absorption efficiency contributed to the mortality event during the first feeding period. J. Morphol., 2010. © 2010 Wiley-Liss, Inc. [source] Skull shape and feeding strategy in Sphenodon and other Rhynchocephalia (Diapsida: Lepidosauria),JOURNAL OF MORPHOLOGY, Issue 8 2008Marc E.H. Jones Abstract The Rhynchocephalia are a group of small diapsid reptiles that were globally distributed during the early Mesozoic. By contrast, the only extant representatives, Sphenodon punctatus and S. guntheri (Tuatara), are restricted to New Zealand off-shore islands. The Rhynchocephalia are widely considered to be morphologically uniform but research over the past 30 years has revealed unexpected phenotypic and taxonomic diversity. Phylogenetically "basal taxa" generally possess relatively simple conical or columnar teeth whereas more derived taxa possessed stouter flanged teeth and sophisticated shearing mechanisms: orthal in some (e.g., Clevosaurus hudsoni) and propalinal in others (e.g., S. punctatus). This variation in feeding apparatus suggests a wide range of feeding niches were exploited by rhynchocephalians. The relationship of skull shape to skull length, phylogenetic grouping, habit, and characters relating to the feeding apparatus are explored here with geometric morphometric analysis on two-dimensional landmarks. Principle components analysis demonstrates that there are significant differences between phylogenetic groups. In particular, Sphenodon differs significantly from all well known fossil taxa including the most phylogenetically basal forms. Therefore, it is not justifiable to use Sphenodon as a solitary outgroup when studying skull shape and feeding strategy in squamates; rhynchocephalian fossil taxa also need to be considered. There are also significant differences between the skull shapes of aquatic taxa and those of terrestrial taxa. Of the observed variation in skull shape, most variation is subsumed by variation in dentary tooth base shape, the type of jaw movement employed (e.g., orthal vs. propalinal) and the number of palatal tooth rows. By comparison, the presence or absence of flanges, dentary tooth number and palatal tooth row orientation subsume much less. Skull length was also found to be a poor descriptor of overall skull shape. Compared to basal rhynchocephalians members of more derived terrestrial radiations possess an enlarged postorbital area, a high parietal, and a jaw joint positioned ventral to the tooth row. Modification of these features is closely associated with increased biting performance and thus access to novel food items. Some of these same trends are apparent during Sphenodon ontogeny where skull growth is allometric and there is evidence for ontogenetic variation in diet. J. Morphol., 2008. © 2008 Wiley-Liss, Inc. [source] Performance of shark teeth during puncture and draw: implications for the mechanics of cuttingBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2010LISA B. WHITENACK The performance of an organism's feeding apparatus has obvious implications for its fitness and survival. However, the majority of studies that focus on chondrichthyan feeding have largely ignored the role of teeth. Studying the functional morphology of shark teeth not only elucidates the biological role that teeth play in feeding, but also provides insight specifically into the evolution of shark feeding because teeth are often the only structures available in the fossil record. In the present study, we investigate the puncture and draw performance of three general categories of extant teeth, tearing-type, cutting-type, and cutting,clutching type, as well as three fossil morphologies, utilizing a universal testing system. Differences in puncturing performance occurred among different prey items, indicating that not all ,soft' prey items are alike. The majority of teeth were able to puncture different prey items, and differences in puncture performance also occurred among tooth types; however, few patterns emerged. In some cases, broader triangular teeth were less effective at puncturing than narrow-cusped teeth. There were no differences between the maximum draw forces and maximum puncture forces. Many of the shark teeth in the present study were not only able to perform draw and puncture equally well, but also many tooth morphologies were functionally equivalent to each other. The findings obtained in the present study lend little support to the belief that shark tooth morphology is a good predictor of biological role. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 271,286. [source] Conodont affinity and chordate phylogenyBIOLOGICAL REVIEWS, Issue 2 2000PHILIP C. J. DONOGHUE ABSTRACT Current information on the conodonts Clydagnathus windsorensis (Globensky) and Promissum pulchrum Kovács- Endrödy, together with the latest interpretations of conodont hard tissues, are reviewed and it is concluded that sufficient evidence exists to justify interpretation of the conodonts on a chordate model. A new phylogenetic analysis is undertaken, consisting of 17 chordate taxa and 103 morphological, physiological and biochemical characters; conodonts are included as a primary taxon. Various experiments with character coding, taxon deletion and the use of constraint trees are carried out. We conclude that conodonts are cladistically more derived than either hagfishes or lampreys because they possess a mineralised dermal skeleton and that they are the most plesiomorphic member of the total group Gnathostomata. We discuss the evolution of the nervous and sensory systems and the skeleton in the context of our optimal phylogenetic tree. There appears to be no simple evolution of free to canal-enclosed neuromasts; organised neuromasts within canals appear to have arisen at least three times from free neuromasts or neuromasts arranged within grooves. The mineralised vertebrate skeleton first appeared as odontodes of dentine or dentine plus enamel in the paraconodont/euconodont feeding apparatus. Bone appeared later, co-ordinate with the development of a dermal skeleton, and it appears to have been primitively acellular. Atubular dentine is more primitive than tubular dentine. However, the subsequent distribution of the different types of dentine (e.g. mesodentine, orthodentine), suggests that these tissue types are homoplastic. The topology of relationships and known stratigraphic ranges of taxa in our phylogeny predict the existence of myxinoids and petromyzontids in the Cambrian. [source] | ||||||||||