Developmental trends in the mouthparts during growth from juvenile to adult of the tropical freshwater crayfish, Cherax quadricarinatus von Martens, 1868 (Decapoda: Parastacidae)

Abstract

The structure and setal armature of the mouthparts of Cherax quadricarinatus during development from juvenile to adult were examined using light and scanning electron microscopy. Significant general transformations include increases in the overall size of the appendages and their component segments or processes, and increases in the number and variety of setal types on the margins and surfaces. Conspicuous transformations that occurred on specific sites of the mouthparts were changes in: (a) the size and shape of third maxilliped and mandibular teeth from canine-like to incisor-shaped or a mixture of somewhat incisor-shaped and canine-like; (b) the setal types replacing other types previously borne on the same site; and (c) the degree of occurrence of the denticulated setae on the 45 mm TL juvenile and adult stages. The implications of these mouthpart transformations on the feeding ability of the early juveniles, late juveniles, and adults are discussed, with mention of the potential ability of the redclaw for suspension feeding. Types of food appropriate for each stage were inferred.