ABSTRACT
Abstract Since the foundation of the Malacological Center in 1980, Universidad Centro Americana (UCA), Managua-Nicaragua, has been monitoring and collecting the marine, terrestrial, fluvial and lake mollusk population of the country. Many specimens have been photographed by Scanning Electronic Microscope (SEM), and in one of these, observation of the hairy periostracum reveals a seemingly thriving population of minute protists in possible symbiosis with their host. Adequate magnification and comparison with previous studies allowed the determination of these hosts as diatoms, testaceous amoebae, yeast, phacus, spores and other undetermined organisms which occur in tropical forests on rocks, trees and leaves. Here illustrated are diatoms and other organisms detected for the first time on the periostracum of a tropical rainforest mollusk.
Resumo Desde a fundação do Centro Malacológico em 1980, a Universidad Central Americana (UCA), Manágua-Nicarágua, vem acompanhando e coletando a população de moluscos marinhos, terrestres, fluviais e lagoas do país. Muitos espécimes foram fotografados pelo microscópio eletrônico de varredura (SEM) e, em um deles, a observação do periostracum peludo revela uma população aparentemente próspera de protistas de minuto em possível simbiose com o hospedeiro. A ampliação adequada e a comparação com estudos anteriores permitem a determinação dessas diatomáceas, amebas testaceas, leveduras, phacus, esporos e outros organismos indeterminados que ocorrem em florestas tropicais em rochas, árvores e folhas. Aqui estão as diatomeas e outros organismos pela primeira vez detectados no periostracum de um molusco tropical.
Subject(s)
Animals , Snails/physiology , Symbiosis , Diatoms/physiology , Microscopy, Electron, Scanning , Diatoms/classification , Rainforest , NicaraguaABSTRACT
Abstract This study evaluated the feeding preference of the invasive mollusk Melaniudes tuberculata between the aquatic macrophytes Egeria densa and Chara indica. The experiment consisted of twelve experimental units (glass aquariums) each of which contained three liters of water and three compartments. Fragments of E. densa and C. indica were placed in separate compartments within each unit; the third compartment, which did not contain macrophytes, was used as the control. Twenty Melanoides tuberculata individuals were placed in each unit and monitored hourly over the course of 24 hours for preferential movements. Physical and chemical water variables were measured at the beginning and end of the experiment. Habitat complexity was determined through collected macrophyte fragments and determined using the Fractop program. After 24 hours, the highest average number of individuals was observed in the treatment with Chara indica (ten individuals), which differed significantly from the treatment with E. densa (four individuals) and the control treatment (two individuals). The number of individuals between the E. densa and control treatment were similar. M. tuberculata showed a clear feeding preference for C. indica.
Resumo O presente trabalho teve como objetivo avaliar a preferência do molusco invasor M. tuberculata pelas macrófitas aquáticas Egeria densa e Chara indica. Doze unidades experimentais (aquários de vidro), com dimensões de 30×15×15 cm, subdivida em três compartimentos foram utilizadas. Em cada unidade experimental foram adicionados três litros de água, sendo que em dois compartimentos foram adicionados aleatoriamente fragmentos de E. densa e C. indica e um compartimento ficou sem planta (controle). Na parte central do aquário foram adicionados os moluscos equidistantes dos três compartimentos. O experimento teve duração de 24 horas, sendo vistoriado e contabilizado o número de organismos presentes em cada compartimento a cada hora. As variáveis ambientais foram medidas no inicio e fim do experimento. Fragmentos de macrófitas foram coletados para determinação da complexidade do habitat através do programa Fractop. Após 24 horas, os resultados mostraram um maior valor médio de indivíduos no tratamento que possuía Chara indica (dez indivíduos), que diferiu significativamente do tratamento com E. densa (quatro indivíduos) e do tratamento controle (dois indivíduos). Os tratamentos com E. densa e o controle foram semelhantes entre si evidenciando, uma possível preferência do molusco por a C. indica.
Subject(s)
Animals , Snails/physiology , Food Chain , Hydrocharitaceae/growth & development , Chara/growth & development , Brazil , Ecosystem , Feeding Behavior , Introduced SpeciesABSTRACT
ABSTRACT The reef-building vermetid Petaloconchus varians occurs in the western Atlantic Ocean, from the Caribbean Sea to the southern coast of Brazil. The present study evaluated the abundance of P. varians on intertidal rocky shores in Ilha Grande Bay (Rio de Janeiro State), and characterized their reefs, describing the species density, besides the weight and the belt width of the reefs. Petaloconchus varians reefs were recorded at 25 sites, with rocky shores exposed to different wave action (very sheltered, sheltered, semi-exposed and exposed) and slopes (10° to 46°). Clusters of individuals constructed large reefs along the middle intertidal zone, creating a wide belt (38 cm to 2 m). The density of P. varians and the weight of the reefs ranged from 620 to 2,559 ind.100 cm-2 and from 100 to 1,500 g.100 cm-2, respectively. Considering that the species was last reported from the area in the mid-20th century, the present study suggests that P. varians reefs are becoming dominant in the intertidal zone of rocky shores in Ilha Grande Bay. This is a contribution to knowledge of this ecosystem in Ilha Grande Bay, in view of local or global ecological changes.
Subject(s)
Animals , Snails/anatomy & histology , Bays , Coral Reefs , Snails/physiology , Water Movements , Atlantic Ocean , Brazil , Population Dynamics , Population Density , Statistics, Nonparametric , Animal Distribution , Marine BiologyABSTRACT
Resumen:Pomacea flagellata es una especie de caracol de agua dulce nativo en el sureste de México. Sobre esta especie existen pocos estudios y en ninguno se han abordado aspectos de su reproducción. Este caracol ha sido explotado durante años en la laguna Bacalar y sus poblaciones han decrecido considerablemente, conllevando a la veda de su captura. Este trabajo se realizó con el objetivo de evaluar las variaciones temporales de la frecuencia de cópulas y la abundancia de masas de huevos de P. flagellata en la laguna de Bacalar, así como sus relaciones con la abundancia de los caracoles y con variables ambientales. Los muestreos fueron realizados durante tres temporadas: Lluvias (julio, agosto y septiembre 2012), Nortes (diciembre 2012, enero y febrero 2013) y Secas (marzo, abril y mayo 2013) en 12 estaciones a lo largo de la laguna de Bacalar. En cada estación, se recorrió un transecto de 100 m paralelo a la orilla y se contó el número de huevas frescas (color rosado) puestas sobre la vegetación, troncos, rocas o estructuras artificiales. En el agua se hicieron tres transectos de 50 x 2 m y en cada uno se contaron los caracoles y se registró el número de cópulas. La densidad de caracoles mostró variaciones significativas entre temporadas, disminuyendo desde la temporada de Lluvias hasta la temporada de Secas. Entre los meses dentro de temporadas no se presentaron diferencias significativas (ANOVA, p>0.05). Durante toda la temporada de Lluvias se registraron cópulas con una frecuencia significativamente mayor que en Nortes, mientras en Secas no se registraron cópulas (Kruskal-Wallis, p˂0.05). La puesta de masas de huevos se extendió de julio a marzo. La densidad de huevas no presentó diferencias entre la temporadas de Lluvias y Nortes (2.72 masas/m y 2.93 masas/m, respectivamente), pero en Secas fue significativamente menor con un valor de 0.1 masas/m (H, p˂0.05). La frecuencia de cópulas se relacionó significativamente con la abundancia de caracoles (rs= 0.26; p<0.05) y con la temperatura del agua (rs= 0.34; p<0.05). La abundancia de masas de huevos se relaciona significativamente con la abundancia de individuos (rs= 0.46; p<0.05). De forma general se observó que la actividad reproductiva de P. flagellata en la laguna de Bacalar, está asociada a los meses más cálidos y con mayor precipitación. Este hallazgo es relevante para apoyar la gestión de este recurso en la región, de tal forma que para implementar alguna medida de manejo para esta especie, es necesario tener en cuenta que al menos se debe mantener una veda temporal durante la etapa reproductiva.
Abstract:The freshwater snail Pomacea flagellata is native from Southeastern Mexico. Studies about this species are scarce and none has treated their reproduction. This snail has been exploited at Bacalar lagoon for many years, leading to a significant decrease in their abundance and currently, a permanent ban was proposed by the government. This work aimed to assess the temporal variations of mating frequency and the abundance of egg clutches of P. flagellata at Bacalar lagoon, as well as their relation with snails density and environmental variables. Sampling was done during the three climatic seasons: Rainy (July, August and September/2012), North or Cold fronts (December/2012 and January and February/2013) and Dry (March, April and May/2013) in 12 sampling stations located along the Bacalar lagoon. On each station a transect of 100 m length was set parallel to the edge, and the number of fresh egg clutches (pink color) laid over vegetation, rocks or manmade structures, were counted. In the water, three 50 x 2 m transects were set and the number of snails were counted as well as the mating frequency. Density of snails varied significantly among seasons, decreasing from the rainy to the dry season. There were no significant differences of snail abundance among months, nested in climatic seasons (ANOVA, p>0.05). During the rainy season the mating frequency was significantly higher than in the Norths, meanwhile in the dry season no mating were registered (Kruskal-Wallis, p˂0.05). Eggs clutches appeared from July to March. Density of egg clutches presented no differences between the Rainy and the North seasons (2.72 and 2.93 clutches/m, respectively), nonetheless during the dry season abundance of egg masses was significantly lower (0.1 clutches/m) (H, p˂0.05). Mating frequency was related with snail abundance (rs= 0.26; p<0.05) and water temperature (rs= 0.34; p<0.05) and the abundance of egg masses is related with snail abundance (rs= 0.46; p<0.05). In general, we observed that reproductive activity of P. flagellata at Bacalar lagoon is related with the warmer months and with higher rainfall. This finding is relevant to support the management of this resource in the region, so that to implement any management arrangement they must be aware that a temporal ban is necessary during the reproductive season at least. Rev. Biol. Trop. 64 (4): 1643-1650. Epub 2016 December 01.
Subject(s)
Animals , Snails/physiology , Oviposition/physiology , Rain , Reproduction/physiology , Seasons , Temperature , Time Factors , Analysis of Variance , Population Density , Climate , Statistics, Nonparametric , Fresh Water , MexicoABSTRACT
Abstract Very little is known about the ecology and biology of Drymaeus tripictus, an extremely rare and endemic land snail species from Costa Rican highlands. I studied the ecology and reproductive biology of D. tripictus from April 2009 through June 2010 in an old forest, a young forest and a Cupressuslusitanica plantation in central Costa Rica. Every three months I visited each habitat and collected specimens in 20 random sampling plots (3x3 m2 each). I observed the snail's activity and microhabitat preference in the field, and in the laboratory I recorded high definition videos of its mating behavior and analyzed reproductive morphology with light microscopy. The snail is more abundant in the old forest (0.017 ind./m2) and prefers leaves with little epiphyllous cover (0-25 % cover, chi-square test, p <0.0001). During the dry season the snails become active between 20:00 pm and 8:00 am (chi-square = 22.65, df=3, p < 0.0001); they are inactive mainly during the afternoon (11:00 am to 16:59 pm). I found active individuals mostly on the upper side of leaves, where they feed (Chi-square =6.76, df=1, p = 0.0093). Mating is unilateral, by shell mounting, with cryptic phallus intromission and without role switching or multiple mating. Its reproductive system is morphologically similar to that of Drymaeus costaricensis. Mating behavior is as expected for snails with high-spired shells, except for the lack of role switching. The density of D. tripictus is low even when compared with other endangered bulimulids. Rev. Biol. Trop. 64 (1): 55-68. Epub 2016 March 01.
ResumenSe conoce muy poco sobre la ecología y biología del caracol terrestre Drymaeus tripictus. Se trata de una especie extremadamente escasa y endémica de las zonas altas de Costa Rica. Estudié la ecología y biología reproductiva de D. tripictus de abril 2009 a junio 2010 en un bosque maduro, un bosque jóven y una plantación de Cupressus lusitanica en Costa Rica. Cada tres meses visité esos hábitats y recolecté especímenes en 20 puntos de muestreo (cada uno de 3x3 m2). Estudié actividad y preferencias de hábitat en la naturaleza. En el laboratorio grabé en alta definición el comportamiento de apareamiento y analicé la morfología reproductiva con un microscopio estereoscópico de luz. El caracol es mas abundante en el bosque maduro (0.017 ind/m2) y prefiere hojas con poca cobertura de epífilos (25% o menos de cobertura, chicuadrado, p < 0.0001). En la época seca, se activan entre las 8:00 pm y las 8:00 am principalmente (chi-cuadrado = 22.65, p <0.0001). En la tarde se inactivan (11:00 am to 16:59 pm). Los individuos activos se encuentran principalmente en el haz de las hojas (Chi-square =6.76, df =1, p = 0.0093), que es donde se alimentan. El apareamiento es unilateral por "montaje de concha", no hacen cambio de roles sexuales y la intromisión fálica es críptica. Su sistema reproductivo es morfológicamente similar al de Drymaeus costarricensis. El comportamiento de apareamiento es como se espera de un caracol de concha con espira alta, excepto por la ausencia de cambio de roles. La densidad de D. tripictus es mas baja que la de otros bulimulidos considerados en peligro.
Subject(s)
Animals , Male , Female , Sexual Behavior, Animal/physiology , Snails/physiology , Reproduction/physiology , Snails/classification , Tropical Climate , Costa RicaABSTRACT
Records of the gastropod Melanoides tuberculatus (Müller, 1774), family Thiaridae, in the Piranhas-Assu River basin in Rio Grande do Norte reveal the dispersal of this native Southeast Asian and East African species into aquatic environments of the Brazilian semiarid region, including artificial environments (reservoirs) and lotic systems. The eutrophic conditions of the local waterbodies appear to favor the present situation, where this invasive species reaches extremely high densities, sometimes over 10,000 ind.m-2 as in Armando Ribeiro Gonçalves Reservoir. These observations indicate the immediate need for new studies on the spatial distribution of the species and its potential impact on the biodiversity and water quality of the waterbodies of the semiarid region of the state. Implantation of regular and systematic monitoring of the aquatic resources of the region is urgently required.
Registros da presença do gastrópode Melanoides tuberculatus (Müller, 1774), família Thiaridae, na bacia do Rio Piranhas-Assú no Rio Grande do Norte, revelam a dispersão desta espécie nativa do sudeste asiático e leste africano para ambientes aquáticos do semiárido brasileiro, incluindo ambientes artificiais (reservatórios) e sistemas lóticos. As condições eutróficas dos corpos d'água potiguares parecem favorecer a presente situação, em que a espécie invasora atingiu densidades extremamente elevadas, com valores acima de 10.000 ind.m-2, como no reservatório Armando Ribeiro Gonçalves. Estas observações indicam a necessidade imediata de novos estudos sobre a distribuição espacial da espécie e seu potencial de impacto sobre a biodiversidade e qualidade da água dos corpos d'água do semiárido potiguar. Neste contexto, torna-se urgente a implantação de um regular e sistemático monitoramento dos recursos hídricos da região.
Subject(s)
Animals , Ecosystem , Environmental Monitoring , Snails/physiology , Brazil , Population Density , Population Dynamics , Rivers , Snails/classificationABSTRACT
Habroconus semenlini is a micro-terrestrial gastropod native to South America. There are no previous studies on its biology. We studied its pattern of growth, fertility and lifespan under laboratory conditions. For this purpose, 80 snails were either grouped or kept isolated (40 animals in each condition) during their lifetime. Growth is indeterminate and the species is capable of self-fertilization with high reproductive success. Grouped snails had lower fecundity than the animals that were kept in isolation. This species has a short lifespan and only one reproductive period, which characterizes the occurrence of semelparity. Rev. Biol. Trop. 57 (4): 1217-1222. Epub 2009 December 01.
Habroconus semenlini es un gastrópodo micro-terrestre nativo de América del Sur. Actualmente se carece de estudios sobre su biología. Este estudio tuvo como objetivo verificar el patrón de crecimiento, la fecundidad y la esperanza de vida de esta especie en condiciones de laboratorio. Con este fin, 80 caracoles fueron mantenidos aislados o agrupados (40 animales en cada condición) durante su ciclo de vida. La especie tiene crecimiento indeterminado y es capaz de auto-fertilización con alto grado de éxito reproductivo. Los caracoles agrupados tuvieron menor fecundidad que los que se mantuvieron en aislamiento. Esta especie tiene una vida útil corta, y sólo un período reproductivo, lo que caracteriza la semelparidad.
Subject(s)
Animals , Female , Male , Life Cycle Stages/physiology , Snails/growth & development , Fertility , Inbreeding , Laboratories , Longevity , Snails/physiology , Time FactorsABSTRACT
Tribulyltin and methanol extract of Dodonaea Viscosa and Haplophyllum tuberculatum plants were tested as molluscicidal agents against Biomphalaria alexandrina snails. In addition, the effect of tributyltin and the two tested plants on the survival rate, egg production, the hatchability of eggs and hermaphrodite glands of B. alexandrina snails was carried out. The results indicated that exposure of B. alexandrina to tributyltin and the tested plants led to a significant reduction in their survival rate, egg production and hatchability of their eggs. This was confirmed by histological examination that showed a severe damage in the hermaphrodite gland cells of treated snails. In addition, tributyltin and methanol extract of D. Viscosa and H. tuberculatum had qualitative and quantitative effect on the protein patterns of snail's hermaphrodite gland. The electrophoretic pattern of the native proteins revealed difference in the number and molecular weights of protein bands compared to the control snails. It was concluded that tribulyltin and the tested plants might be helpful in snail control as they interfere with the snail's biology and physiology
Subject(s)
Herbal , Plant Preparations , Rutaceae/toxicity , Sapindaceae/toxicity , Biomphalaria , Snails/physiology , HistologyABSTRACT
The goal of this study was to document the distribution and establishment A. fulica such as their feeding preference and behavior in situ. The study was carried out at the city of Lauro de Freitas, Bahia state, Brazil, between November 2001 and November 2002. We used catch per unit effort methods to determine abundance, distribution, habitat choice and food preferences. The abundance and distribution of A. fulica was most representative in urban area, mainly near to the coastline. Lots and house gardens were the most preferred sites during active hours. The results indicated that A. fulica started their activity at the end of the evening and stopped in mid-morning. Their preferred food were vascular plants such as Hibiscus syriacus, Ricinus communis, Carica papaya, Galinsonga coccinea, Lippia alba, Ixora coccinea, Musa parasidisiaca, Mentha spicata and Cymbopogon citrates. Our results indicate that A. fulica are well adapted and established in this city and modified environments facilitate their establishment and dispersion. However, human perturbation, such as clearance of lots could be limiting for the persistence of A. fulica populations.
O objetivo deste estudo foi documentar a distribuição e o estabelecimento de Achatina fulica, assim como sua preferência alimentar e aspectos comportamentais in situ. Esta pesquisa foi desenvolvida na cidade de Lauro de Freitas, Estado da Bahia, Brasil, durante os meses de novembro de 2001 a novembro de 2002. Usamos o método de esforço de captura determinado por homem/hora para calcular a abundância e distribuição, habitats preferidos, além de preferência alimentar. Vimos que a abundância e distribuição de A. fulica foram mais representativas em áreas urbanas, sobretudo cerca da linha de costa. Os terrenos e jardins de casas foram os locais preferidos pelos caracóis quando estavam em atividade. Os resultados indicaram que os caracóis A. fulica iniciam sua atividade no final da tarde e hibernam no meio da manhã. A comida preferida destes caracóis foram plantas vasculares como Hibiscus syriacus, Ricinus Communis, Carica papaya, Galinsonga coccinea, Lippia alba, Ixora coccinea, Musa parasidisiaca, Mentha spicata and Cymbopogon citrates. Nossos dados sugerem que o A. fulica está plenamente adaptado e estabelecido nesta cidade e, também, que ambientes modificados facilitam seu estabelecimento e dispersão. Entretanto, a perturbação humana, como a limpeza de terrenos pode ser um fator limitante para a persistência da população de A. fulica.
Subject(s)
Animals , Feeding Behavior/physiology , Snails/physiology , Brazil , Population Density , Population Dynamics , SeasonsABSTRACT
The influence of population density on some aspects of the reproductive biology of the snail Bradybaena similaris was studied. Molluscs were maintained under 0.2 (isolated), 0.3, 0.6, 1.0, 1.3 and 1.7 snail/m² densities. The animals maintained under 0.3 and 0.6 snail/m² showed the lowest numbers of eggs laid/snail, being the highest value observed to the 1.7 snail/m². The hatching of the snails maintained under 0.3 snail/m² density, begun at the 21st day after laying, and the maximum time required to the hatching was 36 days was observed to the eggs came from snails maintained under the densities 0.6, 1.0, 1.3 snail/m², respectively. The highest percentage hatchability (55.56 percent) was observed to isolated snails. The galactogen content in the albumen gland did not seem to accompany the alterations occurred in the reproduction of B. similaris in response to the different population densities.
A influência da densidade populacional em alguns aspectos da biologia reprodutiva do molusco Bradybaena similaris foi estudada. Os moluscos foram mantidos em densidades de 0.2 (isolados), 0.3, 0.6, 1.0,1.3 e 1.7 moluscos/m². Nas densidades de 0.3 e 0.6 moluscos/m², os moluscos apresentaram os menores números de ovos postos por molusco, sendo o maior valor observado para essa variável na densidade de 1.7 molusco/m². A eclosão dos moluscos mantidos a uma densidade de 0.3 molusco/m², iniciou-se aos 21 dias após a postura, sendo o tempo máximo necessário para a eclosão 36 dias para ovos oriundos de moluscos mantidos nas densidades de 0.6, 1.0, 1.3 moluscos/m². O maior percentual de eclosão (55.56 por cento) foi observado para os moluscos isolados. O conteúdo de galactogênio na glândula de albúmem parece não acompanhar as alterações na reprodução de B. similaris em resposta a diferentes densidades populacionais.
Subject(s)
Animals , Female , Galactans/analysis , Oviposition/physiology , Snails/physiology , Population Density , Reproduction/physiology , Snails/anatomy & histologyABSTRACT
The effect of an aversive stimulus represented by contact with a hot plate on the heart rate of Megalobulimus mogianensis was evaluated with electrocardiogram recording in intact snails (N = 8). All stimulated animals showed an increase in heart rate, with mean values ranging from 35.6 ± 1.2 (basal heart rate) to 43.8 ± 0.9 bpm (post-stimulation heart rate). The cardioacceleration was followed by gradual recovery of the basal heart rate, with mean recovery times varying from 4.3 ± 0.3 to 5.8 ± 0.6 min. Repetition of the stimulus did not affect the magnitude of variation nor did it influence the basal heart rate recovery time. To investigate the role of the cardiac nerve in mediating the heart rate alterations induced by the aversive stimulus, denervated (N = 8) and sham-operated (N = 8) animals were also tested. Although the aversive stimulus caused the heart rate to increase significantly in both experimental groups, the mean increase in heart rate in denervated animals (4.4 ± 0.4 bpm) was 57 percent of the value obtained in sham-operated animals (7.7 ± 1.3 bpm), indicating that the cardiac nerve is responsible for 43 percent of the cardioacceleration induced by the aversive stimulus. The cardioacceleration observed in denervated snails may be due to an increase in venous return promoted by the intense muscular activity associated with the withdrawal response. Humoral factors may also be involved. A probable delaying inhibitory effect of the cardiac nerve on the recuperation of the basal heart rate is suggested.
Subject(s)
Animals , Heart Rate/physiology , Heart/innervation , Snails/physiology , Electrocardiography , Hot Temperature , Heart/physiology , Muscles/physiology , Physical Stimulation/methods , Reaction Time/physiology , Reflex/physiologyABSTRACT
In an attempt to elucidate the role of calcium in the life of the edible Achatinid snail, Limicolaria flammea (Miller) I investigated short and long term effects of calcium added to the food. The short term experiments lasted for 18, 30 and 32 weeks respectively, while the long term experiment to determine life time utilization of calcium carbonate lasted for 15 months. In the short term experiments, hatchlings were divided into densities of one, ten and 50 snails. In the 10 snail group, there was a positive correlation between calcium provision, body weight (t test, p < 0.01; r = 0.96, p < 0.0001) and shell length (t test, p < 0.01; r = 0.96, p < 0.00001). There was also a positive correlation between increase in shell length and availability of calcium in the 1 snail group (t test, p< 0.01; r = 0.99, p < 0.00001). In the 50-snail group, the correlation was positive for shell length of the snails (t test, p < 0.05; r = 0.99, p < 0.0001) and body weight (t-test, p < 0.05; r = 99, p < 0.00001). Mortality was very high in the snails deprived of calcium and they did not produce eggs. In the long term experiment, there were three feeding peaks in L. flammea. In the first feeding peak, amount of food and calcium ingested by the snails increased in the first three months of life. The second feeding peak occurred at six months of age, while the last occurred at 10 months of age. The amount of calcium ingested during the second peak decreased gradually in the 4th and 5th month. The amount of calcium ingested was lowest during the 3rd feeding peak. The period of highest weight gained by the snails was between the 1st and 6th month and then dropped at between six and 12 months of age which corresponds to the period of egg production. There were also three peaks of egg production; the first was between six and eight months (535 eggs), the second at between 10 and 11 months (350 eggs) and the third at 13 to 14 months (310 eggs) respectively.
Estudié el efecto de agregar calcio al alimento sobre el desarrollo del caracol pulmonado africano Limicolaria flammea (Müller). La cantidad de calcio tuvo una correlación positiva con el peso corporal (T de Student, p < 0.01; r = 0.96, p < 0.0001) y la longitud de concha (T de Student, p < 0.01; r = 0.96, p < 0.00001). Los caracoles que no recibieron calcio murieron en gran cantidad y no produjeron huevos. En un experimento a largo plazo, hubo picos de consumo del calcio y el mayor aumento de peso fue en los seis meses iniciales. Los picos de producción de huevos fueron entre los seis y los ocho meses (535 huevos), entre los diez y once meses (350 huevos) y en los meses 13 y 14 (310 huevos).
Subject(s)
Animals , Female , Snails/growth & development , Calcium Carbonate/administration & dosage , Calcium, Dietary/administration & dosage , Oviposition/physiology , Snails/anatomy & histology , Snails/physiology , Fertility/physiologyABSTRACT
Demography of the snail Plicopurpura pansa (Neotaenioglossa: Muricidae) and constitution of the associated mollusk community, in Guerrero, Mexico. We quarterly sampled the molluskan community of Playa Ventura, Guerrero, Mexico. Sample size (20 m² in 1m² units) was determined by the spatial distribution pattern of Plicopurpura pansa using a negative binomial distribution. The density of the P. pansa was 5.19 snails/m² and the sex ratio near 1:1. The average size was 20.10 mm (most females were 10.5 to 27.0 mm; most males 12.0 to 27.0 mm). Density was high and small sized dominated. Mean size varied with time. General mean weight was 1.79 g. Females weight varied more, maybe because of the reproductive cycle. Recruits were collected in five samplings. Most copulation activity was in March of 2001. The associated community includes 26 species of Gastropoda, five of Bivalvia and one of Polyplacophora, Brachidontes semilaevis being dominant. Rev. Biol. Trop. 55 (3-4): 867-878. Epub 2007 December, 28.
Estudiamos la demografía de Plicopurpura pansa en Playa Ventura, Guerrero, México, con base en muestreos trimestrales. Su densidad fue de 5.19 caracoles/m². La proporción sexual fue cercana al 1:1. La talla promedio fue de 20.10 mm. Las tallas mejor representadas en hembras fueron de 10.5 a 27.0 mm y en machos de 12.0 a 27.0 mm. La población es de alta densidad y mayor frecuencia de tallas pequeñas. Hubo diferencias entre las tallas promedio de cada muestreo, formándose dos grupos de medias para cada sexo. El peso promedio fue 1.79 g. Las hembras presentaron mayor variación en peso, lo cual podría estar relacionado con el ciclo reproductivo. Hubo reclutamiento en cinco fechas de recolección. El mayor número de cópulas se observaron en marzo de 2001. Se identificaron 26 especies de gasterópodos, siete de bivalvos y una de poliplacóforos. La especie con mayor dominancia fue Brachidontes semilaevis.
Subject(s)
Animals , Female , Male , Snails/classification , Mexico , Population Density , Seasons , Sex Ratio , Snails/anatomy & histology , Snails/physiologyABSTRACT
The survival, reproduction and embryonic development of Strombus pugilis, were determined during a period of ten months under laboratory conditions. Seven progenitors were collected in Contoy Island, Quintana Roo, Mexico and later transferred to the laboratory, where they were placed in aquarium with 80 1 of sea water and fed with "pellets". A total of 30 egg masses were collected, one on September and the other on April. The estimated total length of one egg mass was 11.24 m; the mean number of embryos obtained per 2 cm was 264, obtaining an estimated total of 157 500 embryos in the egg mass. The means of the physical-chemical parameters during the study were: salinity 37.6 +/- 0.5% per hundred, pH 7.5 +/- 0.5 and temperature 28 +/- 0.2 degrees C. The maintenance and water recirculation system used to sustain the breading stock is excellent both for reproduction of the organism and for obtaining egg masses under controlled conditions.
Subject(s)
Animals , Male , Female , Snails/physiology , Snails/growth & development , Snails/embryology , Time Factors , Laboratories , Larva/growth & development , Oviposition/physiology , Reproduction/physiology , Ovum/growth & developmentABSTRACT
The molluscicidal effect of Pittosporum tobira, Abutilon pictum and Thevetia peruviana leaves and seeds powder and ethanol extract against adult Biomphalaria alexandrina snails after 24 hrs of exposure under laboratory conditions showed that T peruviana is the most toxic ones since its LC[90] values were the least among the other tested plants, being 98.8 and 18.5 ppm for the dry powder water suspension and ethanol extract, respectively. Bioinphalaria snails continuously exposed to sublethal concentration [LC[0]=1.2ppm] of the ethanolic extract of T. peruviana exhibited a great reduction in survival rate, being 24% and 2% after 4 and 8 weeks post exposure compared to 76% and 56% for control group, respectively. The egg production of treated snails was significantly reduced from the first week of exposure. Thus, the mean number of eggs/snail/week at the 41h week was 42.2 and 223.3 eggs/snail for treated and control snails, respectively. The exposure of B. alexandrina to sublethal concentration of the ethanolic extract of T. peruviana for 4 weeks led to disturbance in some biochemical parameters. The protein content in the hemolymph and glycogen content in tissues of treated snails were significantly reduced compared to control groups. The ratios of reduction of protein content were 46.7% and 65% respectively. Meanwhile, the alkaline phosphatase activity and the glucose content were increased in the hemolymph of treated snails, than of control ones. The elevation ratios were 72.7% and 88.2%, respectively. The LC[0] of T. peruviana ethanol extract killed 65% of miracidia and 55% of cercariae after one hour of exposure and they were killed after 4 hrs and 5 his after exposure respectively
Subject(s)
Snails/physiology , Rosales , Plant Extracts/therapeutic use , ThevetiaABSTRACT
Pomacea canaliculata is a common gastropod in freshwater habitats from Central and Northern Argentina, extending northwards into the Amazon basin. Several Platyhelminthes have been reported associated to P. canaliculata, sharing an intimate relationship with this gastropod host. The objectives of this study were to describe the symbiotic species assemblages associated to P. canaliculata in the study area, and to disclose differences among them. Samples were taken in three typical small streams and one artificial lentic lagoon, all connected with the Rio de la Plata estuary. The 81.53% were infested with different symbiotic (sensulato) species. Among the Platyhelminthes, the commensal Temnocephala iheringi Haswell, 1893 was highly prevalent in all samples, always in the mantle cavity. Four trematode taxa were recognized: (a) metacercariae of Echinostoma parcespinosum Lutz, 1924 in the mantle cavity and sporocysts in the digestive gland; (b) metacercariae of Dietziella egregia (Dietz, 1909) in the pericardial cavity; (c) unidentified xiphidiocercariae and (d) unidentified sporocysts and furcocercariae in the digestive gland. Nematode larvae and oligochaetes were found in two localities in the mantle cavity. Among the Annelida, Helobdella ampullariae Ringuelet, 1945 was found in the mantle cavity and lung of snails only from one locality. Our results show that although some of the symbionts are present in all localities, others are restricted to some particular ones, whether in their absolute numbers or in their relative abundance. Thus, eachhosting population at the studied localities may be defined by the particularcombination of symbionts that bears.
Subject(s)
Animals , Male , Female , Annelida/physiology , Snails/physiology , Helminths/physiology , Life Cycle Stages , Symbiosis , Trematoda/growth & development , Trematoda/physiology , Argentina , EcosystemABSTRACT
The effects of a brief jet of water delivered to the anterior portion of body-head on the heart rate of Megalobulimus mogianensis were determined in a group of intact snails (N = 8), previously prepared for electrocardiogram recording. The heart rate was significantly increased following stimulation. Nevertheless, with repetition of the stimulus there was a significant decrease in the magnitude of the heart rate variation and in the time for the basal heart rate to recover (first stimulus, 7.4 ± 1.2 bpm and 15.5 ± 1.8 min; second stimulus, 4.8 ± 1.0 bpm and 10.6 ± 1.5 min; third stimulus, 5.0 ± 0.3 bpm and 11.1 ± 1.8 min), indicating that this behavioral response undergoes early habituation. To determine the role of the cardiac nerve in mediating the heart rate alterations induced by the jet of water two other groups were tested: denervated animals (N = 8) and sham-operated control animals (N = 8). Although the innocuous stimulus caused the heart rate to increase significantly in both experimental groups, the mean increase in heart rate in denervated animals (3.2 ± 0.4 bpm) was 41 percent of the value obtained in sham-operated animals (7.8 ± 1.5 bpm), indicating that the cardiac nerve is responsible for 59 percent of the cardioacceleration induced by the innocuous stimulus. The increase in heart rate observed in denervated animals may be due to an increase in venous return promoted by the intense muscular activity associated with the retraction-protraction of the anterior part of the body induced by the jet of water.
Subject(s)
Animals , Heart Rate/physiology , Heart/innervation , Snails/physiology , Electrocardiography , Physical Stimulation/methodsABSTRACT
The intestinal microbiota of the edible snails Cornu aspersum fSyn: H. aspersa), and Helix pomatia were investigated by culture-based methods, 16S rRNA sequence analyses and phenotypic characterisations. The study was carried out on aestivating snails and two populations of H. pomatia were considered. The cultivable bacteria dominated in the distal part of the intestine, with up to 5.10(9) CFU g -1, but the Swedish H. pomatia appeared significantly less colonised, suggesting a higher sensitivity of its microbiota to climatic change. All the strains, but one, shared ¡Ý 97 percent sequence identity with reference strains. They were arranged into two taxa: the Gamma Proteobacteria with Buttiauxella, Citrobacter, Enterobacter, Kluyvera, Obesumbacterium, Raoultella and the Firmicutes with Enterococcus, Lactococcus, and Clostridium. According to the literature, these genera are mostly assigned to enteric environments or to phyllosphere, data in favour of culturing snails in contact with soil and plants. None of the strains were able to digest filter paper, Avicel cellulose or carboxymethyl cellulose (CMC). Acetogens and methanogenic archaea were not cultivated, so the fate of hydrogen remains questionable. This microbiota could play important roles in the digestive process (fermentation) and the energy supply of the snail (L-lactate, acetate). The choice of cereals and plants by snail farmers should take into account the fermentative abilities of the intestinal microbiota.
Subject(s)
Animals , Bacteria/metabolism , Fermentation , Intestines/microbiology , Snails/microbiology , Bacterial Typing Techniques , Bacteria/classification , Bacteria/genetics , Colony Count, Microbial , Phylogeny , RNA, Bacterial/genetics , /genetics , Snails/physiologyABSTRACT
Variações morfológicas nos órgãos do sistema reprodutor dos gastrópodes pulmonados são observadas ao longo do ano e podem ser correlacionadas a fases de seu ciclo reprodutivo. A partir dessa observação, a massa dos órgãos do sistema reprodutor do caracol Megalobulimus abbreviatus foi tomada em cada estação do ano e foram obtidas secções histológicas das gônadas. Os valores de massa foram utilizados para a obtenção do índice organo-somático e as secções, para calcular o diâmetro médio dos ovócitos e o índice de maturação ovocitária. Concluímos que M. abbreviatus é um caracol "iteroparous", apresentando ciclo reprodutivo anual caracterizado por acasalamento e oviposição durante a primavera e o início do verão e pela preparação do sistema reprodutor para um nova fase reprodutiva, que se inicia em janeiro e se estende até o final do inverno.
Subject(s)
Animals , Gonads/growth & development , Snails/physiology , Gonads/cytology , Reproduction/physiology , SeasonsABSTRACT
Our objective is to evaluate the habitat preference of freshwater snails in relation to environmental factors and the presence of the competitor snail Melanoides tuberculatus. In the first phase, snails was collected at 12 sites. This sampling sites presented a degree of organic input. In the second phase 33 sampling sites were chosen, covering a variety of lotic and lentic environments. The snail species found at Guapimirim, state of Rio de Janeiro, displayed a marked habitat preference, specially in relation to the physical characteristics of each environment. Other limiting factors for snail distribution at the studied lotic environments were the water current velocity and the amount of organic matter, mainly to Physa marmorata, M. tuberculatus, and Biomphalaria tenagophila. The absence of interactions between M. tuberculatus and another snails could be associated to the distinct spatial distribution of those species and the instability of habitats. This later factor may favor the coexistence of M. tuberculatus with B. glabrata by reduction of population density. In areas of schistosomiasis transmission some habitat modification may add to the instability of the environment, which would make room for the coexistence of M. tuberculatus and Biomphalaria spp. In this way, some of the usual measures for the control of snail hosts would prevent the extinction of populations of Biomphalaria spp. by M. tuberculatus in particular habitats.