Life-history traits of the red brocade hermit crab Dardanus insignis on the subtropical Brazilian coast

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.