The Vortex Wake of the Free-swimming Larva and Pupa of CULEX PIPIENS (Diptera)

2001 ◽  
Vol 204 (11) ◽  
pp. 1855-1867 ◽  
Author(s):  
John Brackenbury
Keyword(s):  
Reynolds Numbers ◽  
High Amplitude ◽  
The Body ◽  
Ring Vortex ◽  
Free Swimming ◽  
Continuous Surface ◽  
The Mean ◽  
Swimming Larva ◽  
Free Swimming Larva ◽  
Visualisation Technique

SUMMARY The kinematics and hydrodynamics of free-swimming pupal and larval (final-instar) culicids were investigated using videography and a simple wake-visualisation technique (dyes). In both cases, swimming is based on a technique of high-amplitude, side-to-side (larva) or up-and-down (pupa) bending of the body. The pupa possesses a pair of plate-like abdominal paddles; the larval abdominal paddle consists of a fan of closely spaced bristles which, at the Reynolds numbers involved, behaves like a continuous surface. Wake visualisation showed that each half-stroke of the swimming cycle produces a discrete ring vortex that is convected away from the body. Consecutive vortices are produced first to one side then to the other of the mean swimming path, the convection axis being inclined at approximately 25° away from dead aft. Pupal and larval culicids therefore resemble fish in using the momentum injected into the water to generate thrust. Preliminary calculations for the pupa suggest that each vortex contains sufficient momentum to account for that added to the body with each half-stroke. The possibility is discussed that the side-to-side flexural technique may allow an interaction between body and tail flows in the production of vorticity.

Kinematics and hydrodynamics of an invertebrate undulatory swimmer: the damsel-fly larva

2002 ◽  
Vol 205 (5) ◽  
pp. 627-639 ◽  
Author(s):  
John Brackenbury
Keyword(s):  
Large Amplitude ◽  
The Body ◽  
Force Balance ◽  
The Other ◽  
Free Swimming ◽  
Caudal Fin ◽  
Fish Locomotion ◽  
Fly Larvae ◽  
Swimming Larva ◽  
Visualisation Technique

SUMMARYThe kinematics and hydrodynamics of free-swimming larvae of Enallagma cyathigerum were investigated using videography combined with a simple wake visualisation technique (tracer dyes). Damsel-fly larvae are undulatory swimmers with two distinct styles of movement: ‘slow’ swimming, in which body undulation is assisted by paddling of the legs, and ‘fast’ swimming, in which the legs are inactive. In both cases, the wake consists of discrete ring vortices shed from the caudal fin at the end of each half-stroke. The vortices propagate away from the mid-line, alternately to one side of the body then the other, at an angle of 67° from dead aft. There is no aft-flowing jet such as that observed in the wakes of continuously swimming fish that use caudal fin propulsion. The estimated momentum within the vortices, and the resultant thrust on the body are in tolerable agreement with calculations based on the large-amplitude bulk momentum model of fish locomotion. However, the drag on the body is not known, so it cannot be concluded with certainty that a force balance exists. The agreement between experiment and prediction gives confidence to the idea that most, if not all, of the vorticity generated by the swimming larva is located within the observable wake elements.

Calcium accumulation and secretion in the serpulid polychaete Spirorbis spirorbis L. at settlement

1975 ◽  
Vol 55 (4) ◽  
pp. 911-923 ◽  
Author(s):  
J. A. Nott ◽  
K. R. Parkes
Keyword(s):  
Sea Water ◽  
The Body ◽  
Posterior Half ◽  
Free Swimming ◽  
Calcium Accumulation ◽  
Material Forming ◽  
Suitable Substratum ◽  
Swimming Larva ◽  
Free Swimming Larva

When the free-swimming larva of the polychaete tubeworm Spirorbis spirorbis settles permanently on a suitable substratum, it forms a thin, mucous, anchoring tube, which covers only the posterior half of the body. Within 3 h the worm has built a comparatively thick, calcareous tube onto the anterior end of the initial, mucous tube, which later becomes a compressed and folded remnant (Nott, 1973). The volume of calcareous material forming the tube cannot be stored within the body of the larva before settlement and must, therefore, be taken up rapidly from sea water or ingested material.

scholarly journals Ultrastructure of the ciliated cells of the free-swimming larva, and sessile stages, of the marine spongeHaliclona indistincta(Demospongiae: haplosclerida)

2013 ◽  
Vol 274 (11) ◽  
pp. 1263-1276 ◽  
Author(s):  
Kelly M. Stephens ◽  
Alexander Ereskovsky ◽  
Pierce Lalor ◽  
Grace P. McCormack
Keyword(s):  
Ciliated Cells ◽  
Free Swimming ◽  
Swimming Larva ◽  
Free Swimming Larva

scholarly journals Intergenerational transmission of symbiotic bacteria in oviparous and viviparous demosponges, with emphasis on intracytoplasmically-compartmented bacterial types

2007 ◽  
Vol 87 (6) ◽  
pp. 1701-1713 ◽  
Author(s):  
Manuel Maldonado
Keyword(s):  
Microbial Communities ◽  
Symbiotic Bacteria ◽  
Free Swimming ◽  
Transmission Electron ◽  
Early Embryos ◽  
Membrane Bound ◽  
Chondrilla Nucula ◽  
New Generation ◽  
Swimming Larva ◽  
Free Swimming Larva

Recent molecular detection of vast microbial communities exclusively associated with sponges has made evident the need for a better understanding of the mechanisms by which these symbiotic microbes are handled and transferred from one sponge generation to another. This transmission electron microscopy (TEM) study investigated the occurrence of symbiotic bacteria in free-swimming larvae of two viviparous species (Haliclona caerulea and Corticium candelabrum) and spawned gametes of two oviparous species (Chondrilla nucula and Petrosia ficiformis). Complex microbial communities were found in these sponges, which in two cases included bacteria characterized by an intra-cytoplasmic membrane (ICM). When ICM-bearing and ICM-lacking bacteria co-existed, they were transferred following identical pathways. Nevertheless, the mechanism for microbial transference varied substantially between species. In C. nucula, a combination of intercellular symbiotic ICM-bearing and ICM-lacking bacteria, along with cyanobacteria and yeasts, were collected from the mesohyl by amoeboid nurse cells, then transported and transferred to the oocytes. In the case of Corticium candelabrum, intercellular bacteria did not enter the gametes, but spread into the division furrows of early embryos and proliferated in the central cavity of the free-swimming larva. Surprisingly, symbiotic bacteria were not vertically transmitted by P. ficiformis gametes or embryos, but apparently acquired from the environment by the juveniles of each new generation. This study failed to unravel the mechanism by which the intercellular endosymbiotic bacterium found in the central mesohyl of the H. caerulea larva got there. Nevertheless, the ultrastructure of this bacterial rod, which was characterized by a star-shaped cross section with nine radial protrusions, an ICM-bound riboplasm, and a putative membrane-bound acidocalcisome, suggested that it may represent a novel organization grade within the prokaryotes. It combines traits occurring in members of Poribacteria, Planctomycetes and Verrucomicrobia, emerging as one of the most complex prokaryotic architectures known to date.

scholarly journals Dynamics of Attached Cavities on Bodies of Revolution

1992 ◽  
Vol 114 (1) ◽  
pp. 93-99 ◽  
Author(s):  
S. L. Ceccio ◽  
C. E. Brennen
Keyword(s):  
Reynolds Numbers ◽  
Cavitation Number ◽  
The Body ◽  
Cavity Surface ◽  
Bodies Of Revolution ◽  
The Mean ◽  
Cavity Thickness ◽  
Cavity Closure ◽  
Axisymmetric Bodies ◽  
Single Cavity

Attached cavitation was generated on two axisymmetric bodies, a Schiebe body and a modified ellipsoidal body (the I. T. T. C. body), both with a 50.8 mm diameter. Tests were conducted for a range of cavitation numbers and for Reynolds numbers in the range of Re = 4.4 × 105 to 4.8 × 105. Partially stable cavities were observed. The steady and dynamic volume fluctuations of the cavities were recorded through measurements of the local fluid impedance near the cavitating surface suing a series of flush mounted electrodes. These data were combined with photographic observations. On the Schiebe body, the cavitation was observed to form a series of incipient spot cavities which developed into a single cavity as the cavitation number was lowered. The incipient cavities were observed to fluctuate at distinct frequencies. Cavities on the I. T. T. C. started as a single patch on the upper surface of the body which grew to envelope the entire circumference of the body as the cavitation number was lowered. These cavities also fluctuated at distinct frequencies associated with oscillations of the cavity closure region. The cavities fluctuated with Strouhal numbers (based on the mean cavity thickness) in the range of St = 0.002 to 0.02, which are approximately one tenth the value of Strouhal numbers associated with Ka´rma´n vortex shedding. The fluctuation of these stabilized partial cavities may be related to periodic break off and filling in the cavity closure region and to periodic entrainment of the cavity vapor. Cavities on both headforms exhibited surface striations in the streamwise direction near the point of cavity formation, and a frothy mixture of vapor and liquid was detected under the turbulent cavity surface. As the cavities became fully developed, the signal generated by the frothy mixture increased in magnitude with frequencies in the range of 0 to 50 Hz.

Experiments on host-finding and host-specificity in the monogenean skin parasite Entobdella soleae

Parasitology ◽  
1967 ◽  
Vol 57 (3) ◽  
pp. 585-605 ◽  
Author(s):  
G. C. Kearn
Keyword(s):  
Host Specificity ◽  
Host Finding ◽  
Free Swimming ◽  
Solea Solea ◽  
Specific Substance ◽  
The Common ◽  
Mucus Cells ◽  
Common Sole ◽  
Swimming Larva ◽  
Free Swimming Larva

The oncomiracidium of the monogenean skin parasite Entobdella soleae finds its flatfish host, Solea solea, by chemoreception. The free-swimming larva responds to a specific substance secreted by the skin of the common sole, attaches itself to this skin and immediately sheds its ciliated epidermal cells. Larvae respond in the same way to agar jelly which has been in contact with the skin of S. solea.The oncomiracidia attach to S. solea skin in preference to that of other soleid fishes (Buglossidium luteum and Solea variegata), pleuronectid fishes (Limanda limanda, Pleuronectes platessa) and elasmobranch flatfishes (Raia spp.).Larvae respond strongly to isolated epidermis from Solea solea but show no response to the fish's cornea, indicating that the attractive substance is produced by the mucus cells in the fish's epidermis.The larvae attach with equal readiness to skin from the upper and lower surfaces of S. solea. Thus the preponderance of young parasites on the upper surfaces of soles is due not to a preference for the upper skin but to the fact that the lower skin is in contact with the substratum and cannot be reached by the larvae.These results led to speculations on the way in which host specificity evolved in the Monogenea.I am indebted to Mr J. E. Green of the Plymouth Laboratory for setting up a tank containing infected soles and for maintaining the tank and feeding the fishes for many months.I am also grateful to the Directors and Staff of the Plymouth Laboratory and the Fisheries Laboratory, Lowestoft, for hospitality and assistance. I am particularly grateful to Mr J. Riley of the Lowestoft Laboratory for providing various flatfishes.

The oncomiracidia of the monocotylid monogeneans Dictyocotyle coeliaca and Calicotyle kroyeri

Parasitology ◽  
1970 ◽  
Vol 61 (1) ◽  
pp. 153-160 ◽  
Author(s):  
G. C. Kearn
Keyword(s):  
Body Fluid ◽  
Distinct Species ◽  
The Body ◽  
Gland Cells ◽  
Host Body ◽  
To Come ◽  
First Time ◽  
Swimming Larva ◽  
Free Swimming Larva ◽  
Anterior Median

The eggs of D. coeliaca have been cultured successfully and the free-swimming larva has been studied for the first time. The eggs have an incubation period which for monogeneans is exceptionally long (4–5 months at 10 °C). Apart from maintenance at a low temperature no other special conditions such as high hydrostatic pressure or washing to remove host body fluid are necessary for development. It is not necessary for the eggs to come into contact with host body fluid before development can begin.The oncomiracidium of D. coeliaca has no eyes, a well-developed pair of anterior median gland cells and a pair of hamuli. The oncomiracidium of C. kroyeri is similar to that of D. coeliaca except for the presence of two pairs of conspicuous pigmented eyes, poorly developed anterior median gland cells, the presence of an extra pair of gland cells at the posterior end of the body and the absence of hamuli.A comparison of the larval features of D. coeliaca and C. kroyeri has confirmed that these parasites belong to quite distinct species.

V. On the structure, physiology, and development of Antedon ( Comatula , Lamk.) rosaceus

1876 ◽  
Vol 24 (164-170) ◽  
pp. 211-231 ◽  
Keyword(s):  
Deep Sea ◽  
Royal Society ◽  
Free Swimming ◽  
Spare Time ◽  
Type Form ◽  
History Of ◽  
The Subject ◽  
Swimming Larva ◽  
Free Swimming Larva

When, in 1865,1 communicated to the Royal Society the First Part of Monograph on the Anatomy, Physiology, and Development (excluding he earliest stages previously described by Prof. Wyville Thomson) of animal which might be regarded—except in certain comparatively unimportant particulars—as a type-form of the whole Crinoidal series, I had nearly concluded my investigation of the subject of it, that I fully ontemplated the presentation of the Second and concluding part in the course of a year (Jr two. Uncertain health, however, interfered with its ompletion in the first instance; and my spare time has since then been;o far taken up by the various inquiries that have arisen out of the Deep-Sea researches which I prosecuted in the vacations of 1868 and three following years, that I have found myself quite unable to resume the tudy of Antedon . Thus it comes to pass that, though I have now had me for a period of ten years the results of my previous labours, as presented in several hundred preparations, with a series of most admirable Ira wings executed by Messrs. George West and A. Hollick, illustrating almost every point of primary importance not only in its structure, but also in the history of its development from nearly the earliest Pentacrinoid stage, all this material has remained unpublished; for I have felt that the completion of my Monograph in a manner worthy of its subject required that certain obscurities should be dissipated and certain gaps filled up; and it now, also, becomes desirable that the Histology of this type should be more fully elucidated by the aid of modern appliances, and that the earliest phases of its Development should be thoroughly reinvestigated. I especially desire to ascertain whether the free-swimming larva (or pseudembryo) has a Gastrcea stage, and to follow out the derivation of the gastric and perivisceral cavities of the Pentacrinoid, and of its original tentacular system, from the structures of the pseudembryo—points on which Prof. Wyville Thomson’s Memoir, admirable as it is, does not enlighten us. This stage of the history has been subsequently studied by a most able observer, Herr Metschnikoff; and the conclusions he has arrived at in regard to the origin of the tentacular system I find to be essentially accordant with those which I had drawn from my own researches on a later stage.

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