ABSTRACT
La historia natural de los camarones fantasma, conocidos por modelar la estructura de las comunidades en hábitats de aguas someras, ha sido poco estudiada en el Pacífico suramericano. Aquí presentamos información ecológica concerniente a Callichirus seilacheri, con base en individuos recolectados entre enero y diciembre de 2003 en playa Las Machas, norte de Chile. La densidad de las madrigueras varió entre 1.4 y 20.2 madrigueras / 0.25 m2, y fue mayor durante el verano (18.2 madrigueras / 0.25 m2). La proporción de sexos fue 1:1 durante la mayor parte del periodo de estudio; sin embargo, las hembras superaron en número a los machos en enero y setiembre. Los machos presentaron un tamaño máximo mayor al de las hembras (27.1 y 24.0 mm CL, respectivamente). La presencia de juveniles se restringió principalmente al periodo comprendido entre febrero y mayo. La madurez sexual se alcanza a un tamaño de CL de 20.8 mm en los machos y 18.1 mm en las hembras. El periodo reproductivo principal se extendió del otoño al invierno (de mayo a agosto, con un pico en junio), y coincidió con temperaturas decrecientes en el agua y con la presencia de una capa de sedimento sobre las madrigueras.
The life history of ghost shrimps, known for their role in shaping community structures in shallow water habitats, is poorly studied in species occurring along the coasts of the South American Pacific. Here we present ecological information concerning Callichirus seilacheri based upon individuals collected from January to December 2003 in Las Machas beach, northern Chile. Burrow densities varied between 1.4 and 20.2 burrows / 0.25 m2, and was highest during summer (18.2 burrows / 0.25m2). The sex proportion was 1:1 during most of the study period; however, females outnumbered males in January and September. Males reached a larger maximum size than females (27.1 and 24.0 mm CL, respectively). The presence of juveniles was restricted principally to the time between February and May. Sexual maturity was reached at a size of 20.8 mm (males) and 18.1 mm CL (females). The main breeding period lasted from autumn to winter (May to August, peaking in June), and co-occurred with decreasing water temperatures and the presence of a sediment layer covering the burrows.
Subject(s)
Animals , Male , Female , Decapoda/growth & development , Ecology , Sexual Maturation/physiology , Analysis of Variance , Chile , Ecosystem , Pacific Ocean , Population Density , Population Dynamics , Regression Analysis , Reproduction , SeasonsABSTRACT
The land crab Gecarcinus quadratus is an engineering species that controls nutrient cycling in tropical forests. Factors regulating their coastal distribution are not fully understood. We quantified land crab distribution during the dry season at Sirena Field Station in Corcovado National Park, Costa Rica, and found that land crab burrow density decreases with increasing distance from the ocean. Leaf litter depth and tree seedling density are negatively correlated with land crab burrow density. Burrows are strongly associated with sand substrate and burrow density is comparatively low in clay substrate. Results suggest that G. quadratus is limited to a narrow coastal zone with sand substrate, and this distribution could have profound effects on plant community structure.
Subject(s)
Animals , Brachyura/physiology , Seasons , Costa Rica , Population Density , Population DynamicsABSTRACT
Scorpions arc generally non-social, solitary animals that interact with conspecifics at birth, courtship or predation only· The present study reports the presence of advanced sub social behaviour in Heterometrus fulvipes Brunner and evaluates the importance of its burrowing as a cause for such social behaviour· Heterometrus fulvipes constructed deep angular burrows at the base of plants· Burrows provided (i) protection against predation, (ii) increased availability of food and (iii) ideal microclimate for year round activity of the scorpions· No cannibalism was observed in laboratory maintained colonies· The risk of predation and the difficult by immatures to dig tunnels during dry soil conditions may have forced the mother and offspring to live together in the burrow for longer durations. The cohabitation of relative offsprings transforms the burrow into a nest· The members of a colony exhibits division of labour for nest expansion and in foraging· The mother communicates with the immatures through "Buzz" sound and may provide premasticated food· There is food sharing also among colony members· All these behaviours indicate the presence of advanced sub social behaviour in Heterometrus fulvipes·
ABSTRACT
The burrow density of sympatric murids in relation to various abiotic factors viz· maximum and minimum atmospheric temperatures, relative humidity, soil temperature and soil moisture was studied in the agro-ecosystem of village Kakrod-Jind (Haryana) Analysis of monthly recorded data on burrow density revealed a biomodal pattern i. e. a peak each during the months of September and March· Of these abiotic factors, soil moisture revealed significant positive correlation with the burrow density whereas relative humidity exhibited invariably the least interaction· However, path co-efficient analysis depicted the direct effects of soil temperature and soil moisture and indirect effect of maximum and minimum atmospheric temperature through soil temperature on the burrow density· The use of path co-efficient analysis in such studies has been suggested·