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Slender Body (slender + body)

Distribution by Scientific Domains

Life Sciences	80%

Selected Abstracts

The LGL (Lighthill,Gueron,Liron) Theorem,historical perspective and critique

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 17-18 2001
Nadav Liron
The 1970s saw a series of works on the modelling of slender bodies moving in slow flow (Re=0), instigated by the interest to understand the principles underlying the swimming of ciliates and flagellates. It was Lighthill in 1975, who wrote down the first theorem connecting slender body motion and singularities distributions along the centre line. This paper will describe the historical development from the early results through Lighthill's theorem to the Gueron,Liron Theorem, which enables discrete-cilia modelling, i.e., modelling of a multitude of slender bodies attached to a surface. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Food abundance affects both morphology and behaviour of juvenile perch

ECOLOGY OF FRESHWATER FISH, Issue 2 2008
J. Borcherding
Abstract,,, Behaviour and morphology were both shown to differ between 1+ perch from two lakes that in earlier studies showed differences in size-specific predation risk. As the level of nourishment is known to affect behaviour and morphology, we fed perch of the two lakes in tanks for 40 days with two food levels, to study whether observed differences remain stable with changes in food availability. The perch fed in excess grew significantly, while the perch at the low food conditions lost weight, clearly indicating undernourishment. In aquarium experiments, the starved perch from both lakes were much bolder in the trade-off between foraging and predator avoidance than their well-fed conspecifics. In addition, the shape of perch differed significantly between feeding treatments. At low food levels perch got a more slender body, while at high food levels they developed a deeper body and a relatively smaller head. Independent of feeding level, the comparison between the two lakes revealed a clearly deeper body and a larger head area for one population, a shape difference that remained stable after the feeding period. The results give evidence that the level of nourishment is an important factor that quickly alters risk-taking behaviour. In body morphology, however, more stable shape characteristics must be distinguished from more flexible ones. Consequently, the level of nourishment is a potential factor that may quickly hide other proximate cues and must be considered attentively in studies, in which shape changes and behaviour are related to environmental factors like diet, predation pressure or habitat diversity. [source]

TRITURUS NEWTS DEFY THE RUNNING-SWIMMING DILEMMA

EVOLUTION, Issue 10 2006
Lumíl Gl
Abstract Conflicts between structural requirements for carrying out different ecologically relevant functions may result in a compromise phenotype that maximizes neither function. Identifying and evaluating functional trade-offs may therefore aid in understanding the evolution of organismal performance. We examined the possibility of an evolutionary trade-off between aquatic and terrestrial locomotion in females of European species of the newt genus Triturus. Biomechanical models suggest a conflict between the requirements for aquatic and terrestrial locomotion. For instance, having an elongate, slender body, a large tail, and reduced limbs should benefit undulatory swimming, but at the cost of reduced running capacity. To test the prediction of an evolutionary trade-off between swimming and running capacity, we investigated relationships between size-corrected morphology and maximum locomotor performance in females of ten species of newts. Phylogenetic comparative analyses revealed that an evolutionary trend of body elongation (increasing axilla-groin distance) is associated with a reduction in head width and forelimb length. Body elongation resulted in reduced maximum running speed, but, surprisingly, also led to a reduction in swimming speed. The evolution of longer tails was associated with an increase in maximal swimming speed. We found no evidence for an evolutionary trade-off between aquatic and terrestrial locomotor performance, probably because of the unexpected negative effect of body elongation on swimming speed. We conclude that the idea of a design conflict between aquatic and terrestrial locomotion, mediated through antagonistic effects of body elongation, does not apply to our model system. [source]

A new case of intralacustrine radiation in Amphipoda.

JOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 2 2009
A new genus, Amphipoda) from the ancient lake Fuxian Hu in Yunnan, China, three new species of Anisogammaridae (Crustacea
Abstract Fuxian Hu is a deep freshwater lake in the high plateau in Yunnan Province, China. After a study and description of Fuxiana yangi Sket, 2000 from deep waters, some coastal samples of amphipods were taxonomically evaluated. Four species were recognized, which in winter co-occur along most of the shallow littoral zone around the lake; they were identified as members of the family Anisogammaridae. One species was recognized as a slightly differentiated Eurypodogammarus helobius Hou et al., 2005, and the others as new species of Fuxigammarus gen. n. Results of a cladistic analysis performed on morphological characters from published descriptions, which included all lacustrine taxa and representatives of all other anisogammarid genera, established the monophyly of the new genus. Endemic character and monophyly of the group testify to an intralacustrine radiation within Fuxigammarus. Fuxian Hu is the fifth known lake in the world to contain a radiation of amphipods and is the only one inhabited by members of Anisogammaridae. Fuxigammarus gen. n. is characterized by a small and slender body, scant dorsal setosity-spinosity, and single, sausage-shaped accessory lobes on coxal gills, antennae without calceoli and rod shaped uropod III. These species differ substantially from each other by characters that do not occur in other anisogammarid genera. The type species F. antespinosus sp. nov. has spiniform dorsal setae shifted forward. Fuxigammarus barbatus sp. nov. has extremely setose antennal bases and mandibular palps and an elongated proximal flagellar article of antenna II. Fuxigammarus cornutus sp. nov. has a pair of dorsal spiniform setae only on humped urosomite I and the usually spiniform setae replaced by flexible setae on the telson. These characters are a kind of counterpart to the specific body armature of the Bajkal amphipods. Zusammenfassung Fuxian Hu ist ein tiefer Süßwassersee auf dem Hochplateau der Yunnan-Provinz in China. Nach der Beschreibung von Fuxiana yangi Sket, 2000 aus den Tiefen des Sees wurden auch Amphipoden-Proben aus dem Litoralbereich taxonomisch ausgewertet. Vier Arten wurden erkannt, die im Winter gemeinsam das flache Litoral rund um den See bewohnen. Sie wurden der Familie Anisogammaridae zugeordnet. Eine der Arten konnte als leicht differenzierte Eurypodogammarus helobius Hou et al., 2005 bestimmt werden, während die anderen als neue Arten einer neuen Gattung, Fuxigammarus gen.nov., beschrieben werden. Die Monophylie der neuen Gattung wurde durch eine phylogenetische Analyse bestätigt, die alle im See bekannten Arten sowie Vertreter aller anderen Anisogammariden-Gattungen mit einbezog. Der Endemismus und die Monophylie der Gattung deuten auf eine intralakustrische Radiation von Fuxigammarus. Somit ist Fuxian Hu der fünfte See weltweit, in dem eine Radiation von Amphipoden nachgewiesen wurde, und der einzige davon mit Anisogammariden. Fuxigammarus gen. n. besitzt einen kleinen und schlanken Körper, eine arme Dorsalbestachelung, nur je eine Nebenast auf jeder Coxalkieme, Antennen ohne Calceoli und stabförmige Uropoden III. Sie unterscheiden sich deutlich in Merkmalen, die bei anderen Anisogammariden nicht vorkommen. Die Typusart F. antespinosus sp. nov. besitzt nach vorne verdrängte Dorsal-Stacheln. Fuxigammarus barbatus sp. nov. hat dicht setose Antennenenbasen und Mandibularpalpen sowie ein verlängertes proximales Glied im Flagellum der Antenne II. Fuxigammarus cornutus sp. nov. besitzt nur ein Paar stachelförmige Dorsal-Setae auf dem gewölbtem Urosomit I, und weiche anstatt der sonst normalen stachelförmigen Setae auf dem Telson. Diese Merkmale wirken wie ein Gegenstück zu den spezifischen Schutzstrukturen der Baikal-Amphipoden. [source]

Morphology and Infraciliature of Three Species of Metaurostylopsis (Ciliophora, Stichotrichia): M. songi n. sp., M. salina n. sp., and M. marina (Kahl 1932) from Sediments, Saline Ponds, and Coastal Waters

THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 1 2005
Yanli Lei
Abstract. Two new urostylid ciliates, Metaurostylopsis songi n. sp. and Metaurostylopsis salina n. sp. and Metaurostylopsis marina (Kahl 1932) are investigated using live observation and protargol impregnation. These species were isolated in Korea from intertidal sediments, saline ponds, and coastal waters. Metaurostylopsis songi is in vivo about 120 ,m × 25 ,m, has a slenderly ellipsoidal body, colorless cortical granules in rows on ventral and dorsal body sides, about 54 macronuclear nodules, 28,47 adoral membranelles, five frontal, two or three frontoterminal and six or seven transverse cirri, and 9,12 midventral cirral pairs followed posteriorly by 1,3 single cirri. In vivo M. salina is about 60 ,m × 25 ,m, has a pyriform body, colorless cortical granules irregularly arranged, about 45 macronuclear nodules, 18,23 adoral membranelles, three frontal, three to five frontoterminal and two to five transverse cirri, and four or five midventral cirral pairs followed posteriorly by five to seven single cirri. Both species have three marginal cirral rows on each body side and 3 long dorsal kineties. The Korean specimens of M. marina match the Chinese population in all main features. Metaurostylopsis songi differs from M. marina by the more slender body, the number of frontal cirri (invariably five vs. four), and the arrangement of cortical granules (in rows on dorsal and ventral cortex vs. only along dorsal kineties and anterior body margin). Metaurostylopsis salina differs from its congeners by the distinctly smaller size, the pyriform body shape, the scattered cortical granules (vs. in rows), and number of frontal cirri. It differs from M. marina also by the number of midventral cirral pairs (four or five vs. seven to 11). [source]