Fluid transmission and filtration efficiency of the labral fans of black fly larvae (Diptera: Simuliidae): hydrodynamic, morphological, and behavioural aspects

1993 ◽  
Vol 71 (1) ◽  
pp. 148-162 ◽  
Author(s):  
Jean O. Lacoursière ◽  
Douglas A. Craig
Keyword(s):  
Filtration Efficiency ◽  
Suspension Feeding ◽  
Optimal Filtering ◽  
Feedback Process ◽  
Simulium Vittatum ◽  
Active Feedback ◽  
Flow Through ◽  
Feeding Process ◽  
Behavioural Aspects ◽  
Feeding Behaviours

Body stance and water flow through the labral fans of suspension-feeding Simulium vittatum Zetterstedt larvae were examined using dead and live larvae. Transmission of flowing water through the fans was determined by means of dye injections. Feeding stance is the outcome of an active feedback process between flow forces and behavioural reactions that maintains the fans in an optimal filtering position. Fans responded to velocity increases through structural reconfiguration, which resulted in an increase in aperture size. As the velocity decreased, an increased fraction of the water directly approaching the fan aperture flowed around its perimeter, with no flow through the fans below 2.5 cm∙s−1. Fluid transmission never exceeded 30–35%, even at velocities up to 50 cm∙s−1. Calculations of suspension-feeding efficiency are reformulated to reflect labral fan transmission and behavioural components of the feeding process. Simulium vittatum larvae are consequently shown to be 4–26 times more efficient in filter feeding than has been previously assessed. The effect of flow on labral fan transmission is discussed in relation to known habitat choices and feeding behaviours of simuliid larvae.

scholarly journals THE FINE STRUCTURE AND FUNCTION OF THE TENTACLE IN TOKOPHRYA INFUSIONUM

1965 ◽  
Vol 25 (3) ◽  
pp. 459-477 ◽  
Author(s):  
Maria A. Rudzinska
Keyword(s):  
Electron Microscope Study ◽  
Structure And Function ◽  
The Body ◽  
Feeding Apparatus ◽  
Dense Bodies ◽  
Structural Details ◽  
Flow Through ◽  
Feeding Process ◽  
Fine Structure And Function ◽  
And Function

The feeding apparatus of Suctoria consists of long, thin, stiff tubes called tentacles. When a swimming prey attaches to the tip of the tentacle a number of events follow in rapid succession. The tentacle broadens, a stream of tiny granules starts to move upward at its periphery to the tip, the prey becomes immobilized and shortly thereafter the cytoplasm of the still living prey begins to flow through the center of the tentacle to the body of the predator. An electron microscope study of the tentacle in Tokophrya infusionum, a protozoan of the subclass Suctoria, has disclosed a number of structural details which help to clarify some of the mechanisms involved in this unusual way of feeding. Each tentacle is composed of two concentric tubes. The lumen of the inner tube is surrounded by 49 tubular fibrils most probably of contractile nature. In the inner tube the cytoplasm of the prey is present during feeding, and in the outer tube are small dense bodies. It was found that the dense bodies originate in the cytoplasm of Tokophrya. They have an elongate, missile-like appearance, pointed at one end, rounded at the other, and are composed of several distinct segments. At the tip of the tentacle they penetrate the plasma membrane, with their pointed ends sticking out. It is assumed that the missile-like bodies play a major role in the feeding process. Their composite structure suggests that they might contain a number of enzymes which most probably are responsible for the various events preceding the actual food intake.

Is there an association between milk type and complementary feeding behaviours? A questionnaire survey

2020 ◽  
Vol 8 (3) ◽  
pp. 118-126
Author(s):  
Miranda Spooner
Keyword(s):  
Infant Feeding ◽  
Questionnaire Survey ◽  
Complementary Feeding ◽  
Solid Food ◽  
Health Visitors ◽  
Feeding Methods ◽  
Feeding Process ◽  
Additional Support ◽  
The Relationship ◽  
Feeding Behaviours

When babies are introduced to solid food before the age of 6 months there is some evidence to suggest an association with being overweight, particularly in babies who are formula fed. However, the most recent Infant Feeding Survey, carried out in 2010, found that 30% of mothers had started the complementary feeding process by 4 months and that these parents were more likely to introduce their baby to processed baby foods. The aim of this study was to better understand the relationship between milk type in the first 6 months and complementary feeding methods. By identifying characteristics associated with low compliance, it is hoped that the results of this study will enable health visitors to target their advice, providing additional support to those who are most likely to need it, with the aim of improving compliance with current recommendations for starting solid food.

WHEN DOES MOTION RELATIVE TO NEIGHBORING SURFACES ALTER THE FLOW THROUGH ARRAYS OF HAIRS?

1994 ◽  
Vol 193 (1) ◽  
pp. 233-254 ◽  
Author(s):  
C Loudon ◽  
B Best ◽  
M Koehl
Keyword(s):  
Reynolds Number ◽  
Fluid Flow ◽  
Gas Exchange ◽  
Flow Fields ◽  
Physical Models ◽  
Suspension Feeding ◽  
Flow Through ◽  
Unbounded Fluid ◽  
Hair Diameter

Many animals from different phyla use structures bearing arrays of hairs to perform a variety of important functions, such as olfaction, gas exchange, suspension feeding and locomotion. The performance of all these functions depends on the motion of water or air around and through these arrays of hairs. Because organisms often move such hair-bearing appendages with respect to their bodies or the substratum, we assessed the effects of such motion relative to walls on the fluid flow between neighboring hairs. We compared flow fields near dynamically scaled physical models of hairs moving near walls with those calculated for such hairs in an unbounded fluid. Our results suggest that the methods an organism can use to change the flow through a hair-bearing appendage differ with Reynolds number (based on hair diameter). When Re is 10(-2) or below, changing speed does not alter the proportion of the fluid that moves through rather than around the array, whereas moving relative to a wall increases it. In contrast, when Re is between 10(-2) and 1, changes in speed have a big effect on the proportion of fluid moving through the array, while moving near walls makes little difference.

Filter feeding in larvae of Simuliidae (Diptera: Culicomorpha): aspects of functional morphology and hydrodynamics

1982 ◽  
Vol 60 (4) ◽  
pp. 712-724 ◽  
Author(s):  
Douglas A. Craig ◽  
Mary M. Chance
Keyword(s):  
Water Flow ◽  
Body Shape ◽  
The Body ◽  
Larval Feeding ◽  
Cross Sectional ◽  
Simulium Vittatum ◽  
Optimal Flow ◽  
Flow Through ◽  
Sectional Shape ◽  
Opening And Closing

The feeding mechanism of simuliid larvae is further elucidated by detailed study of the nature and speed of cephalic fan and mouthpart movements, and examination of water flow around larvae. Photographic observations of artificial particles flowing past Simulium vittatum Zett. larvae show the body and head to be highly streamlined and water flow to be laminar over the larva. Dissections and cinephotography show cephalic fan closure to be initiated and controlled by rotation and medial movement of the torma. As the primary fan closes, the median and secondary fans close and form raised sides to the primary fan. Sharp movements made during opening and closing of the fan suggest the presence of "click mechanisms."One cephalic fan closes and adducts every 0.231 s, and for the period analyzed, one or other fan was closed 28% of the time. It is suggested that the time fans are closed should be included in calculations of simuliid larval feeding efficiencies. Larvae with slower mouthpart movements may filter more efficiently than those with faster movements.Laminar flow through and cross-sectional shape of fan rays produce optimal flow for filtration. Probably turbulent flow at higher velocity may explain observed decreases in feeding efficiencies. Behaviour, body shape, and structure of simuliid larvae are highly adapted for optimal water flow over body and fans, even when gross flow in the habitat is turbulent.

Development of apical pits in chloride cells of the gills of Pimephales promelas after chronic exposure to acid water

1983 ◽  
Vol 41 ◽  
pp. 462-463
Author(s):  
Richard L. Leino ◽  
Jon G. Anderson ◽  
J. Howard McCormick
Keyword(s):  
Confidence Interval ◽  
Chronic Exposure ◽  
Lake Superior ◽  
Pimephales Promelas ◽  
Chloride Cells ◽  
Fathead Minnows ◽  
Secondary Lamellae ◽  
Untreated Water ◽  
Water Ph ◽  
Flow Through

Groups of 12 fathead minnows were exposed for 129 days to Lake Superior water acidified (pH 5.0, 5.5, 6.0 or 6.5) with reagent grade H2SO4 by means of a multichannel toxicant system for flow-through bioassays. Untreated water (pH 7.5) had the following properties: hardness 45.3 ± 0.3 (95% confidence interval) mg/1 as CaCO3; alkalinity 42.6 ± 0.2 mg/1; Cl- 0.03 meq/1; Na+ 0.05 meq/1; K+ 0.01 meq/1; Ca2+ 0.68 meq/1; Mg2+ 0.26 meq/1; dissolved O2 5.8 ± 0.3 mg/1; free CO2 3.2 ± 0.4 mg/1; T= 24.3 ± 0.1°C. The 1st, 2nd and 3rd gills were subsequently processed for LM (methacrylate), TEM and SEM respectively.Three changes involving chloride cells were correlated with increasing acidity: 1) the appearance of apical pits (figs. 2,5 as compared to figs. 1, 3,4) in chloride cells (about 22% of the chloride cells had pits at pH 5.0); 2) increases in their numbers and 3) increases in the % of these cells in the epithelium of the secondary lamellae.

Flow Through Heterogeneous Geologic Media

2015 ◽  
Author(s):  
Tian-Chyi Yeh ◽  
Raziuddin Khaleel ◽  
Kenneth C. Carroll
Keyword(s):  
Flow Through ◽  
Geologic Media
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