GILL STRUCTURE AND GILL-CLEANING MECHANISMS OF THE REDCLAW CRAYFISH CHERAX QUADRICARINATUS (DECAPODA, ASTACIDEA, PARASTACIDAE)

Abstract

Abstract The redclaw crayfish Cherax quadricarinatus is a freshwater species native to northern Australia, but it has been widely translocated overseas for aquaculture. Its gill complement consists of 21 trichobranchiate gills and a rudimentary epipod bearing tubular gill filaments. Gill size decreases from the outer layer of the podobranchs to the inner layers of the arthrobranchs and pleurobranchs. Most gill filaments have a thick epithelium and rounded apex, while a few are thinner and have pointed or hooked tips. The gross structure of the fused epipods and podobranchs from the anterior to posterior limbs suggests a serial pattern of morphological development. The redclaw crayfish has passive gill-cleaning mechanisms using the multidenticulate setae on epipods, setobranchs, scaphognathites, and the inner surface of branchiostegites. Limb motion causes the epipodal and setobranch setae to be jostled, scraping gill surfaces, and agitating the podobranchs whose outer filaments are picked and brushed by t...