Hermaphroditism in some marine animals

Hermaphroditism, a phenomenon in which one and the same individual produces sperms, the male gamate the ovum, the female gamate, is generally common in plants and lower animals and hence is considered as a primitive character. However, it is rare in higher invertebrates such as insects, spiders, prawns and also in the lower vertebrates to which fishes belong. Prawns and fishes have highly evolved reproductive systems and occur as separate individuals of males and females. Both these groups do have some species which are regurarly hermaphrodites and others which are teratologically hermaphrodites

Population biology of spine shrimp Exhippolysmata oplophoroides (Holthuis) (Caridea, Hippolytidae) in a subtropical region, São Paulo, Brazil Biologia populacional do camarão espinho Exhippolysmata oplophoroides (Holthuis) (Caridea, Hippolytidae) numa região subtropical, São Paulo, Brasil

The population biology of Exhippolysmata oplophoroides (Holthuis, 1948) was studied in Ubatuba Bay (23º26'S, 45º02'W), Ubatuba, São Paulo, Brazil, from September/1995 to August/1996. Each sampling comprised eight transects (14 000 m² each), sampled monthly with three repetitions. The specimens were classified with respect to the presence or absence of eggs in the abdominal appendages. Spine-shrimps occurred only on six transects, being most abundant on transect II, with the highest incidence in late spring and throughout the summer months. Ovigerous and non-ovigerous shrimps were present year-round, in an approximately similar proportion (1:1). Site II in Ubatuba Bay is characterized by high salinity and oxygen values, temperature between 26 and 29ºC, low organic matter content in the sediment, and a bottom composed of very fine sand; these environment and biological features allow the establishment and maintenance of the population of E. oplophoroides.<br>A biologia populacional de Exhippolysmata oplophoroides (Holthuis, 1948) foi estudada na enseada de Ubatuba (23º26'S, 45º02'W), Ubatuba, São Paulo, Brasil, de setembro de 1995 até agosto de 1996. Cada amostragem compreendeu oito transectos (14000 m² cada), amostrados mensalmente com três repetições. Os espécimes foram classificados quanto à presença ou ausência de ovos nos apêndices abdominais. Os camarões espinhos ocorreram somente em seis transectos, sendo mais abundantes no transecto II, com a maior incidência no final da primavera e ao longo dos meses de verão. Indivíduos ovígeros e não ovígeros estiveram presentes o ano todo, numa proporção semelhante a 1:1. O transecto II é caracterizado por altos valores de salinidade e oxigênio, temperatura entre 26 e 29º C, baixo teor de matéria orgânica e sedimento composto por areia muito fina. Tais características biológicas e ambientais permitem o estabelecimento e a manutenção da população de E. oplophoroides na região de estudo