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Frameschi I.F.,NEBECC Nucleo de Estudos em Biologia | Frameschi I.F.,São Paulo State University | Andrade L.S.,NEBECC Nucleo de Estudos em Biologia | Andrade L.S.,São Paulo State University | And 8 more authors.
Marine Biology Research | Year: 2015

Abstract: We evaluated the population characteristics of Dardanus insignis, focusing on the reproductive period, juvenile recruitment, sexual maturity, growth and longevity of the species. Samples were collected monthly over two years (1998 and 1999), by trawling, in a subtropical region of Brazil. The hermit crabs were counted by demographic group, weighed and measured for cephalothoracic shield length, and their gonadal stage was identified using a stereo microscope. A total of 3169 hermit crabs were captured (1838 males and 1331 females). Ovigerous females were found from September to March; juvenile recruitment occurred throughout the year, peaking in summer. Males reached sexual maturity at larger sizes than females (cephalothoracic shield length = 4.4 and 4.1 mm, respectively). Longevity was estimated at 6.9 years for males and 4.3 years for females. The seasonal reproductive strategy, sexual maturity at similar sizes for males and females, continuous recruitment and differential growth are basic factors in the establishment and maintenance of the high abundance of D. insignis compared with other hermit crab species in the same region. © 2014, © 2014 Taylor & Francis.

Freire F.A.M.,Federal University of Rio Grande do Norte | Luchiaric A.C.,Federal University of Rio Grande do Norte | Fransozobd V.,NEBECC Nucleo de Estudos em Biologia | Fransozobd V.,Instituto Federal Of Educacao
Indian Journal of Marine Sciences | Year: 2011

Present study consists the study on environmental substrate preference and daily habitual activity of X. kroyeri shrimp. Six different substrate combinations were tested using silt and clay, various granulometries of sand, and gravel. Experimental tank for preference testing consisted of a 50 cm diameter cylindrical tank with 6 lateral compartments and a radial area in the middle. Every substrate combination prepared was randomly chosen for each compartment. Each substrate was spread to have a 5 cm thickness in the compartments. One isolated individual for each trial (n= 40) was used. Activities of the animals were observed 8 times a day, at 13:30, 14:30, 17:30, 18:30, 0:30, 1:30, 7:30 and 8:30 h. X. kyoyeri had a significant preference for very fine and fine sand. During the day light time burrowing activity was more intense while at night swimming was higher. Present results enabled us to conclude that X. kroyeri has preference for very fine and fine sand substrate.

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