Passive Flotation Research Articles

Endoparasitic infections in captive wild mammals under human care in San Luis Potosí, Mexico

Objective: To determine the prevalence, richness and parasitic load in wild mammals of Tangamanga I and II Parks in San Luis Potosí, SLP. To assess whether infections are related to the type of feeding and weather seasons. Design/methodology/approach: Analysis of fresh feces collected for three consecutive days at two sampling stations. Passive flotation techniques with sodium nitrate (qualitative) and McMaster (quantitative) were used. Results: The overall prevalence observed was 36% (n=242). The parasitic wealth is formed by protozoa: Eimeria sp., Isospora sp. and Cystoisospora sp.; by the cestode Moniezia expansa, nematodes: Toxocara sp., Toxascaris sp., Ancylostoma sp./Uncinaria sp., Strongyloides sp., Trichuris suis and Strongylid eggs. The parasite load in the case of protozoa was in the range of 0 – 8505 oocysts per gram of faeces, and 0 – 1400 eggs per gram of faeces in the case of helminths. Statistical analyses showed that the prevalence of parasites does not depend on the climatic season, and only in Tangamanga II Park is the prevalence dependent on the type of feeding (herbivores). Study limitations/implications: The conservation method used limits the stool test techniques that can be employed (stool culture or sporulation). Findings/conclusions: Endoparasitic infections can be a potential risk to the health of animals. In particular to those of great genetic value such as species threatened with extinction. In addition, the potentially zoonotic parasites observed pose a threat to the health of caregivers

Further evaluation and validation of the VETSCAN IMAGYST: in-clinic feline and canine fecal parasite detection system integrated with a deep learning algorithm

BackgroundFecal examinations in pet cats and dogs are key components of routine veterinary practice; however, their accuracy is influenced by diagnostic methodologies and the experience level of personnel performing the tests. The VETSCAN IMAGYST system was developed to provide simpler and easier fecal examinations which are less influenced by examiners’ skills. This system consists of three components: a sample preparation device, an automated microscope scanner, and analysis software. The objectives of this study were to qualitatively evaluate the performance of the VETSCAN IMAGYST system on feline parasites (Ancylostoma and Toxocara cati) and protozoan parasites (Cystoisospora and Giardia) and to assess and compare the performance of the VETSCAN IMAGYST centrifugal flotation method to reference centrifugal and passive flotation methods.MethodsTo evaluate the diagnostic performance of the scanning and algorithmic components of the VETSCAN IMAGYST system, fecal slides were prepared by the VETSCAN IMAGYST centrifugal flotation technique with pre-screened fecal samples collected from dogs and cats and examined by both an algorithm and parasitologists. To assess the performance of the VETSCAN IMAGYST centrifugal flotation technique, diagnostic sensitivity and specificity were calculated and compared to those of conventional flotation techniques.ResultsThe performance of the VETSCAN IMAGYST algorithm closely correlated with evaluations by parasitologists, with sensitivity of 75.8–100% and specificity of 93.1-100% across the targeted parasites. For samples with 50 eggs or less per slide, Lin’s concordance correlation coefficients ranged from 0.70 to 0.95 across the targeted parasites. The results of the VETSCAN IMAGYST centrifugal flotation method correlated well with those of the conventional centrifugal flotation method across the targeted parasites: sensitivity of 65.7–100% and specificity of 97.6–100%. Similar results were observed for the conventional passive flotation method compared to the conventional centrifugal flotation method: sensitivity of 56.4–91.7% and specificity of 99.4–100%.ConclusionsThe VETSCAN IMAGYST scanning and algorithmic systems with the VETSCAN IMAGYST fecal preparation technique demonstrated a similar qualitative performance to the parasitologists’ examinations with conventional fecal flotation techniques. Given the deep learning nature of the VETSCAN IMAGYST system, its performance is expected to improve over time, enabling it to be utilized in veterinary clinics to perform fecal examinations accurately and efficiently.Graphical

Retrospective analysis of feline intestinal parasites: trends in testing positivity by age, USA geographical region and reason for veterinary visit

BackgroundThe goals of this retrospective study were to estimate parasite positivity in samples from cats using zinc sulfate fecal flotation by centrifugation (“centrifugation”) and coproantigen and examine trends with age, geographical region and reason for visit to veterinarian. Common methods of parasite detection, such as centrifugal flotation, passive flotation, or direct smear, may underrepresent the true prevalence of intestinal parasites in cats. Coproantigen testing detects more positive samples than traditional methods alone.MethodsFeline fecal test results from the continental USA containing results for fecal exams performed using centrifugation paired with coproantigen results for ascarid, hookworm, whipworm and Giardia were obtained from the database of a national commercial reference laboratory comprised of multiple regional sites.ResultsParasite positivity was highest in samples from young cats and decreased with cat age. The western region of the USA had lower total parasite positivity than other regions for all parasites except Giardia. Cats receiving fecal tests during veterinary wellness visits had only slightly lower parasite positivity than samples from cats during sick clinical visits.ConclusionsThis study showed a larger population of cats are at increased risk of parasitism than commonly believed and coproantigen testing produces more positive test results for the four parasites that antigen can detect than centrifugation of feline fecal samples.

Evaluation of the VETSCAN IMAGYST: an in-clinic canine and feline fecal parasite detection system integrated with a deep learning algorithm

BackgroundFecal examination is an important component of routine companion animal wellness exams. Sensitivity and specificity of fecal examinations, however, are influenced by sample preparation methodologies and the level of training and experience of personnel who read fecal slides. The VETSCAN IMAGYST system consists of three components: a sample preparation device, a commercially available scanner, and an analysis software. The VETSCAN IMAGYST automated scanner and cloud-based, deep learning algorithm, locates, classifies, and identifies parasite eggs found on fecal microscopic slides. The main study objectives were (i) to qualitatively evaluate the capabilities of the VETSCAN IMAGYST screening system and (ii) to assess and compare the performance of the VETSCAN IMAGYST fecal preparation methods to conventional fecal flotation techniques.MethodsTo assess the capabilities of VETSCAN IMAGYST screening components, fecal slides were prepared by the VETSCAN IMAGYST centrifugal and passive flotation techniques with 100 pre-screened fecal samples collected from dogs and cats and examined by both the algorithm and parasitologists. To determine the diagnostic sensitivity and specificity of the VETSCAN IMAGYST sample preparation techniques, fecal flotation slides were prepared by four different techniques (VETSCAN IMAGYST centrifugal and passive flotations, conventional centrifugal flotation, and passive flotation using OVASSAY® Plus) and examined by parasitologists. Additionally, required sample preparation and scanning times were estimated on a subset of samples to evaluate VETSCAN IMAGYST ease-of-use.ResultsThe algorithm performance of the VETSCAN IMAGYST closely matched that of the parasitologists, with Pearsonʼs correlation coefficient (r) ranging from 0.83–0.99 across four taxa of parasites, Ancylostoma, Toxocara, Trichuris and Taeniidae. Both VETSCAN IMAGYST centrifugal and passive flotation methods correlated well with conventional preparation methods on all targeted parasites (diagnostic sensitivity of 75.8–100%, specificity of 91.8–100%, qualitative agreement between methods of 93.8–94.5%). Sample preparation, slide scan and image analysis were completed within 10–14 min by VETSCAN IMAGYST centrifugal and passive flotations, respectively.ConclusionsThe VETSCAN IMAGYST scanning system with the VETSCAN IMAGYST sample preparation methods demonstrated a qualitative match in comparison to the results of parasitologists’ examinations with conventional fecal flotation techniques. The VETSCAN IMAGYST is an easy-to-use, next generation qualitative and possibly quantitative diagnostic platform that brings expert clinical results into the hands of veterinary clinics.

Not playing by the rules: Unusual patterns in the epidemiology of parasites in a natural population of feral horses (Equus caballus) on Sable Island, Canada.

Sable Island, Nova Scotia, Canada hosts one of few natural populations of feral horses (Equus caballus) never exposed to anthelmintics. Coproculture revealed cyathostomes, Strongylus equinus, S. edentatus, and S. vulgaris, with S. equinus (unusually) dominating in adult horses and cyathostomes dominating in young horses (<3 years of age). We examined 35 horses found dead in the springs of 2017 and 2018, as well as fecal samples from live horses in spring (n = 45) and summer 2018 (n = 236) using McMaster fecal flotation and Baermann larval sedimentation on fresh samples, and modified Wisconsin flotation and sucrose gradient immunofluorescent assay for Giardia and Cryptosporidium on frozen samples. Mean strongyle fecal egg counts were 666 eggs per gram (EPG) in dead horses, 689 EPG in live horses in spring, and 1105 EPG in summer; domestic horses are usually treated at counts exceeding 200 EPG. Adult horses (unusually) had patent infections with the lungworm Dictyocaulus arnfieldi and ascarids (Parascaris spp.), and in spring, dead horses had 5 times higher odds of having patent ascarid infections than live horses, likely due to malnutrition and corresponding immunodeficiency. Fecal prevalence and intensity of D. arnfieldi and Parascaris spp. were significantly higher in young horses, and in spring versus summer. A higher proportion of fecal samples were positive for strongyle and ascarid eggs using a centrifugal flotation technique on previously frozen feces, as compared to a passive flotation method on fresh feces. Eggs of the tapeworm Paranoplocephala mamillana were present in fecal samples from 28% of live, and 42% of dead, horses in spring. This research represents several new geographic records (S. edentatus, D. arnfieldi, and Eimeria leuckarti), provides insight into unusual patterns of parasite epidemiology in a nutrition-limited environment, and has conservation and biosecurity implications for this unique equine population, as well as for parasite management in domestic horses.

Pixel by pixel: real-time observation and quantification of passive flotation speeds of three common equine endoparasite egg types

The efficacy of anthelmintic treatments against populations of endoparasites infecting livestock throughout the world is decreasing. To mitigate this, the use of fecal egg counts is recommended to determine both the necessity, and to ensure the appropriate choice, of anthelmintic treatment. Traditionally, and in order to facilitate easier identification and/or enumeration, samples are analysed after separating eggs from other fecal particulates by exposing them to a solution with a density higher than that of the eggs, but lower than the remaining fecal contents. While many parasite egg flotation protocols exist, little is known about the characteristics of these eggs with respect to their movement through a flotation solution. In this study, we have demonstrated a novel method for the observation and quantification of microscopic (65–100 µm) objects as they experience unassisted flotation. This also represents, to our knowledge for the first time, that the flotation of parasite eggs has been observed and their movement characteristics quantified as they float through solution. Particle tracking and video analysis software were utilised to automatically detect and track the movement of individual eggs as they floated. Three 30 s videos and one 2 min video of each egg type were analysed. If the first 30 s of video were discounted, the differences in mean flotation speed among all videos was statistically significant between egg types (P = 0.0004). Strongyle type eggs (n = 201) moved the fastest with a mean 51.08 µm/s (95% confidence interval: 47.54–54.62). This was followed by Parascaris spp. (n = 131) and Anoplocephala perfoliata eggs (n = 322), with mean speeds of 44.43 µm/s (95% confidence interval: 39.47–49.4) and 31.11 µm/s (95% confidence interval: 29.6–32.61), respectively. This method for evaluating the mean speed of passive flotation may represent a first step towards further optimizing fecal egg flotation and be of interest to parasitologists and veterinary practitioners.

Coproantigen Detection Augments Diagnosis of Common Nematode Infections in Dogs

Microscopic methods which employ active or passive flotation have been used to detect parasite diagnostic stages in the feces of companion animals for many years. More recently, coproantigen ELISAs for the detection of excretory/secretory products from intestinal nematodes have been introduced. These assays can identify the presence of parasites when eggs are not recovered by flotation (e.g. prepatent infection or intermittent egg shedding). The study was designed to assess the added benefit of these coproantigen tests in canine fecal diagnostics. The work was performed at 3 separate sites where canine fecal samples were each independently evaluated by both centrifugal flotation with an expert examiner (CFE) and passive flotation with a less experienced examiner. All samples were also tested using coproantigen ELISA to detect ascarid, hookworm, or whipworm antigen (IDEXX Laboratories, Inc, Westbrook, Maine). A total of 1202 samples were collected; 626 were from shelter dogs and 576 were from pet dogs. CFE recovered ascarid eggs in 58 samples, hookworm eggs in 229 samples, and whipworm eggs in 95 samples. Of the positive samples identified by CFE, the PFE and ELISA identified 40 and 51 ascarid samples, 188 and 203 hookworm samples, and 65 and 67 whipworm positive samples, respectively. The coproantigen ELISA identified 8 ascarid, 82 hookworm, and 22 whipworm positive samples that were not detected by CFE. The combined results of passive flotation and the coproantigen ELISA improved the percent agreement with centrifugal flotation, suggesting that greater sensitivity of detection may be achieved through the use of complementary diagnostic methods. However, errors of misidentification and poor recovery apparently introduced by less experienced examiners using an inferior flotation method remained. A diagnostic approach that combines coproantigen assays with centrifugal flotation and examination by an expert allows detection of more ascarid, hookworm, and whipworm infections.

Separation and Analysis of Microplastics and Nanoplastics in Complex Environmental Samples.

The vast amount of plastic waste emitted into the environment and the increasing concern of potential harm to wildlife has made microplastic and nanoplastic pollution a growing environmental concern. Plastic pollution has the potential to cause both physical and chemical harm to wildlife directly or via sorption, concentration, and transfer of other environmental contaminants to the wildlife that ingest plastic. Small particles of plastic pollution, termed microplastics (>100 nm and <5 mm) or nanoplastics (<100 nm), can form through fragmentation of larger pieces of plastic. These small particles are especially concerning because of their high specific surface area for sorption of contaminants as well as their potential to translocate in the bodies of organisms. These same small particles are challenging to separate and identify in environmental samples because their size makes handling and observation difficult. As a result, our understanding of the environmental prevalence of nanoplastics and microplastics is limited. Generally, the smaller the size of the plastic particle, the more difficult it is to separate from environmental samples. Currently employed passive density and size separation techniques to isolate plastics from environmental samples are not well suited to separate microplastics and nanoplastics. Passive flotation is hindered by the low buoyancy of small particles as well as the difficulty of handling small particles on the surface of flotation media. Here we suggest exploring alternative techniques borrowed from other fields of research to improve separation of the smallest plastic particles. These techniques include adapting active density separation (centrifugation) from cell biology and taking advantage of surface-interaction-based separations from analytical chemistry. Furthermore, plastic pollution is often challenging to quantify in complex matrices such as biological tissues and wastewater. Biological and wastewater samples are important matrices that represent key points in the fate and sources of plastic pollution, respectively. In both kinds of samples, protocols need to be optimized to increase throughput, reduce contamination potential, and avoid destruction of plastics during sample processing. To this end, we recommend adapting digestion protocols to match the expected composition of the nonplastic material as well as taking measures to reduce and account for contamination. Once separated, plastics in an environmental sample should ideally be characterized both visually and chemically. With existing techniques, microplastics and nanoplastics are difficult to characterize or even detect. Their low mass and small size provide limited signal for visual, vibrational spectroscopic, and mass spectrometric analyses. Each of these techniques involves trade-offs in throughput, spatial resolution, and sensitivity. To accurately identify and completely quantify microplastics and nanoplastics in environmental samples, multiple analytical techniques applied in tandem are likely to be required.

Giardia spp., ten years of parasitological data in the biggest zoo of Latin America

Giardia spp. (Diplomonadida: Hexamitidae) is an important and widely studied protozoan parasite with worldwide distribution. Nowadays have six described species, and the most important probably is Giardia duodenalis due to the zoonotical potential that some assemblages have. Many studies analysing samples from wild animals have detected Giardia in captive environment, including the zoonotic type. The aim of this study was to determine the prevalence of Giardia sp. in wild captive animals at São Paulo Zoo, using conventional parasitological techniques (direct smear, passive flotation with saturated sodium chloride solution and simple gravity sedimentation), from 2006 to 2016. In total, 7066 coprological exams were performed during this period with samples from mammals, birds, reptiles and amphibians. The prevalence of Giardia infections was of 1.5% (103/7066). Mammals had the higher prevalence of infections with 2% (77/3872), followed by birds with 1.1% (25/2186) and reptiles with only one positive sample (1/894). All samples from amphibians were negative. Representatives of thirteen families presented positive results for this parasite: Dromaidae, Phasianidae, Ramphastidae, Cervidae, Giraffidae, Canidae, Felidae, Herpestidae, Myrmecophagidae, Callithrichidae, Cebidae, Hylobatidae and Dipsadidae. This study presents the first report of Giardia sp. in Pavo muticus and Brachyteles arachnoides. Infections were prevalent in Cebidae and Ramphastidae species. The findings of this study highlight the importance of identifying which Giardia assemblage are involved in the infections and if they may have a zoonotic potential.

A Survey of Intestinal Parasites of Domestic Dogs in Central Queensland.

Australia has a very high rate of dog ownership, which in some circumstances may lead to exposure to zoonotic parasitic diseases from those companion animals. Domestic dog faecal samples (n = 300) were collected from public spaces and private property in the greater Rockhampton (Central Queensland) region and tested for intestinal helminths and protozoa by direct microscopy, two flotation methods and a modified acid-fast stain for cryptosporidia. Intestinal parasites detected included hookworms (25%), Cystoisospora ohioensis complex (9%), Blastocystis hominis (3%), Giardia duodenalis (3%), Spirometra erinacei (1%) and Toxocara canis (1%), Sarcocystis spp. (2%), Cryptosporidium spp. (2%) and Cystoisospora canis (1%). One infection each with Trichuris vulpis, Dipylidium caninum and a protozoa belonging to the Entamoeba histolytica complex were identified. Sheather’s sucrose centrifugal flotation was more sensitive than saturated salt passive flotation, but no single test detected all cases of parasitic infection identified. The test methodologies employed are poor at recovering larva of Strongyloides stercoralis, Aleurostrongylus abstrussis and eggs of cestodes such as Echinococcus granulosis, so the potential presence of these parasites in Central Queensland domestic dogs cannot be excluded by this survey alone.

Flotation of Toxocara canis Eggs in Commercial Bleach and Effects of Bleach Treatment Times on Larval Development in These Eggs.

Toxocara canis is a common intestinal nematode of young dogs. Puppies contaminate the environment with large numbers of eggs that can embryonate and become infective in less than a month. Embryonated eggs are infectious for humans and other paratenic hosts. Most T. canis infections in humans are asymptomatic; however, migration of T. canis larvae in the eye and in the central nervous system can result in vision loss, blindness, and even death. The eggs of T. canis are highly resistant to harsh environmental conditions and routinely used chemical disinfectants. The objective of this study was to evaluate the effects of full-strength commercial bleach (5.25% sodium hypochlorite solution) treatment on development of T. canis eggs and to report our serendipitous finding that T. canis eggs in dog feces can float in passive fecal flotation tests using bleach. We also demonstrated that T. canis eggs could be identified using the McMaster's fecal eggs counting test using 100% bleach. Toxocara canis eggs collected from the feces of naturally infected 4-8 wk old puppies were treated with full-strength bleach (5.25% sodium hypochlorite solution) for 15 min, 30 min, 60 min, and 120 min; washed free of bleach smell by centrifugation; and resuspended in 0.1 N sulfuric acid solution to undergo larval development at room temperature for 18 days after exposure to bleach. Motile larvae were observed in T. canis eggs in all groups treated for 15-120 min and eggs continuously exposed to bleach for 18 days. Our results indicate that bleach may not be an appropriate disinfectant for dog kennels, cages, or laboratory utensils and work surfaces. Toxocara canis eggs are resistant to bleach treatment and continue to pose a risk for canine and human infections. Further study is needed to find the most appropriate methods for disinfection and removal of eggs to reduce the risk of transmission of this parasite.

Prevalence of Giardia spp. in young dogs using a combination of two diagnostic methods.

In this study, prevalence of the protozoan parasites from the genus Giardia spp, with zoonotic potential and worldwide dissemination, was accessed in young dogs, which are reported as having higher prevalence rates. With that purpose, 49 animals from the Grupo de Intervenção Cinotécnico of the Guarda Nacional Republicana (Portuguese Gendarmerie Canine Unit) were chosen. They were housed individually in areas with a high number of kennels (up to 100), with ages ragging from newborns to 10 years old. Dogs were divided in four groups, according their age: under 6 months (n = 16), 6-12 months (n = 6), 12-18 months (n = 13) and 18-24 months (n = 14), comprising 22 females and 27 males. Fecal samples were collected from every animal and all were submitted to two different diagnostic tests, a passive flotation technique with a ZnSO4 solution and a detection of fecal antigen using a commercially available ELISA test (Witness® Giardia - Zoetis). From the 49 samples, 5 (10.2%) were considered positive with ZnSO4 flotation technique and 6 (12.24%) with the Witness® Giardia test. When considering the combination of both tests, 5 animals (10.2%) were considered positive. Of these, 3 (60%) were from the group under 6 months old, 1 (20%) from the 6-12 months and 1 from the 18-24 (20%) months. Within each group, in the under 6 months group 18.75% (n = 16) were considered positive, 16.67% in the 6-12 month group (n = 6), 0% in the 12-18 month group (n=13) and 7.14% in 18-24 month group (n = 14). None of the animals had clinical signs and no significant differences were found when comparing prevalence according to age, breed or gender. A combination of fecal flotation and antigen ELISA tests have good sensitivity and are easy to perform in practice and, therefore, could be a good choice to perform a diagnostic and small animal veterinarians should have this possible diagnostic in mind when in the present of clinical signs, particularly in young dogs.

Solid/Liquid Separation of Pig Manure by Biological Flotation: Pilot-Scale Study

Many problems are associated with pig manure production like high biochemical oxygen demand, chemical oxygen demand, nitrogen, and phosphorus contents. Manure produces may be used in land spreading for agricultural purposes. Over application of liquid manure or runoff caused by precipitation contribute notably to surface or overland flow of phosphorus. In this study, the LISOX process is proposed for use in medium size farms, namely a 2,000-head swine farm. The LISOX process uses biological passive flotation, without any gas addition, to enable the flocs to rise to the surface. Results show that this technology is able to considerably reduce the solids content in the final effluent to 1.1±0.3% and reached solids content of 17.9±2.6% in the combined solid manure obtained at the end of the LISOX process. Total phosphorus (Pt) concentrations have been reduced from 1,234±428 mg/L to 146±46 mg/L in the final effluent, while a value of Pt of 20.6±7.9 g/kg has been obtained in the final solid fraction of the treated manure. The initial ammonium ion/total phosphorus ratio of 2.3±1.0 has been increased to respectively 16.4±4.6 and 17.6±5.4 after the primary and the secondary flotation, which is clearly much higher than the target value (NH4/Pt>7).

Comparison of Passive Fecal Flotation Run by Veterinary Students to Zinc-Sulfate Centrifugation Flotation Run in a Diagnostic Parasitology Laboratory

The sensitivity of fecal examination methods can be influenced by both technician error and methodology. In this analysis, we compared the results of 335 passive fecal flotation examinations performed on the feces of stray dogs by 3rd-yr veterinary students at the University of Pennsylvania, School of Veterinary Medicine, to the results obtained through zinc-sulfate centrifugation performed by the diagnostic parasitology laboratory on the same fecal samples. The students' passive flotation results agreed with the laboratory zinc-sulfate centrifugation for only 62.4% of samples. Students were able to diagnose 75.0% of Ancylostoma caninum cases, 71.4% of Toxocara canis cases, 54.2% of Trichuris vulpis cases, 26.7% of Cystoisospora spp. (C. ohioensis-like and C. canis) cases, and 14.7% of Giardia lamblia cases. There were also 70 instances where students reported the presence of parasites in the sample that were not diagnosed by zinc-sulfate centrifugation. Based on the overall study findings, passive fecal flotation examinations run in private practice could be missing up to 50.5% of infected dogs, due to either technician error or inherent limitations to the passive fecal flotation technique.

THE SETTLEMENT OF POST LARVAL MYTILUS EDULIS (SETTLEMENT OF POST LARVAL MUSSELS)

It is probable that post larval mussels cut their byssus moorings. For those that gain their freedom in this way, two modes of passive flotation are possible. In the ‘summer’ mode, they are lifted into the water column on the end of a mucus filament; in the ‘winter’ mode, they attach themselves to certain negatively buoyant debris which leaves the bottom when the tide flows. Passive flotation prolongs the errant existence of post larval mussels by increasing their drag. By enabling them to avoid silt and keep in touch with hard substrates, passive flotation makes it more likely that they will settle advantageously. The two modes of passive flotation pose an all-the-year-round threat of fouling to the cooling water systems of coastal power stations.

Controlling factors in the evolution of the graptolites

SummaryRecent ideas on evolution in the graptolites have been based upon an assumption either of passive flotation and passive feeding, or of active and co-ordinated ciliary feeding resulting in automobility. These ideas are compared and a possible evolutionary consequence of automobility is suggested.

Behavior of the Planktonic Coelenterates, Sarsia tubulosa, Phialidium gregarium, and Pleurobrachia pileus in Salinity Discontinuity Layers

The behavior of Sarsia tubulosa (M. Sars 1835), Phialidium gregarium (L. Agassiz 1862), and Pleurobrachia pileus (O. F. Müller 1776) was investigated in chambers where salinity discontinuity layers could be established. Sarsia tubulosa and P. pileus aggregated at the layer for salinity discontinuities of as little as 2‰ although P. gregarium showed more variable behavior. This aggregation was shown to be due to an active response rather than passive flotation in the density barrier set up when low salinity water is placed over high salinity water. Sarsia tubulosa also showed increased fishing activity in any column containing a discontinuity layer compared with any homogeneous control column.

Featherwing Beetles (Insecta: Coleoptera: Ptiliidae)

Featherwing beetles are the smallest known beetles, the majority of the species being a millimeter or less in length. The common name is derived from the distinctive structure of the wings which are believed to function primarily for passive flotation, as in the ciliate seeds of dandelions. These wings are normally folded out of sight under the wing covers or elytra, which in some genera are shortened and truncate. However, in preserved specimens the featherwings often project beyond the apex of the elytra and aid (together with the minute body size) in the recognition of this family. This document is EENY-177 (originally published as DPI Entomology Circular 218), one of the Featured Creatures series of the Entomology and Nematology Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Published: November 2000.&#x0D; EENY177/IN334: Featherwing Beetles (Insecta: Coleoptera: Ptiliidae) (ufl.edu)