The biology of a population of Ebalia tuberosa (Crustacea : Decapoda : Leucosiidae) from the Clyde Sea area

Abstract

Ebalia tuberosa lives on subtidal gravelly substrata. The crabs are sexually dimorphic, adult females being larger than adult males. The female: male sex-ratio is 1.14:1. Post-larval E. tuberosa pass through approximately seven instars before terminal anecdysis. Crabs above a carapace length of about 4 mm moult during one short period of the year only, around August. The terminal moult is also the pubertal moult for both sexes. In sexually mature females there is present a spacious abdominosternal chamber in which the eggs are carried during the incubation period. The crabs mate in November, both sexes being ‘hard’. The eggs are laid shortly afterwards. Approximately 2400 eggs are laid, which are incubated for 7-8 months. The eggs develop rapidly soon after laying but development apparently stops over winter and resumes again in spring. Hatching begins and larvae appear in the plankton in June. The crabs live for at least 2 years following terminal anecdysis and produce a brood each year.