Distribuição temporal e aspectos reprodutivos de Cerebratulus Lineolatus Coe, 1905 (NEMERTEA: HETERONEMERTEA), em uma praia do Nordeste Brasileiro

Abstract

Nemerteans are animals with simple reproductive system, composed by saculiformes gonads without cells or specialized agencies in stock or gamete maturation. They are dioecious, mostly, and with external fertilization. While the role of Nemerteans as prey and predator is already well known, there are few studies on its life cycle and reproduction. Therefore, aim of this study is to characterize some aspects of reproductive biology of Cerebratulus lineolatus, through the characterization of the internal morphology of their reproductive system. In addition, to setting whether it is possible to distinguish males from females in the field through its color pattern. Still, studying the population aspects of Cerebratulus lineolatus on a tropical beach in northeastern Brazil, analyzing its abundance, sex ratio, population structure, reproductive period and type of sediment that this species inhabits. Therefore, monthly collections were carried out between April 2014 and March 2015, in periods of low syzygy tides. The collected animals were measured, photographed and examined histologically. The results were analyzed using the statistical program PAST 3.1 and ANASED particle size analysis program. From the analysis, it was revealed that: the coloring of in vivo the gonads of C. lineolatus are not related to sex or maturation of the gonads. Males and females have gonads occupying the entire body diameter, full of gametes when fully mature. The male gametes are organized in clusters during and after their maturation. The female gametes are attached to the wall of the gonad during maturation, being released into the lumen when mature. The transport of gametes takes place through vesicles and the release takes place directly in the water column. A total of 45 animals were collected, 19 males and 19 females. It was impossible to determine the sex of 7 individuals. Males had an average length of 98.6 ± 35.6 mm, not being significantly larger than females (91 ± 32.2). The animals were present throughout the study period, except in August 2014. Their abundance was not related to rainfall or sea surface temperature. The sediment that 87.8% of these animals inhabit is classified as medium or coarse, poorly or very poorly selected sands. The animals reproduce throughout the year, with reproductive peaks at the end of the dry season.