The crustacean cuticle does not record chronological age: New evidence from the gastric mill ossicles. Issue 5 (September 2018)

• Record Type: Journal Article
• Authors: Becker, Carola; Dick, Jaimie T.A.; Cunningham, Eoghan Mánus; Schmitt, Clemens; Sigwart, Julia D.
• Is Part Of: Arthropod structure & development. Volume 47:Issue 5(2018)
• Page Start: 498
• Page End: 512
• Publication Date: 2018-09
• Subjects: Lobster -- Crab -- Age determination -- Sclerochronology -- Ecdysis -- Moulting; Arthropoda -- Morphology -- Periodicals; Arthropoda -- Anatomy -- Periodicals; Arthropoda -- Cytology -- Periodicals; Arthropods -- growth & development -- Periodicals; 595
• DOI: 10.1016/j.asd.2018.07.002
• Languages: English
• ISSNs: 1467-8039

Abstract

Abstract: A proposed method to determine chronological age of crustaceans uses putative annual bands in the gastric mill ossicles of the foregut. The interpretation of cuticle bands as growth rings is based on the idea that ossicles are retained through the moult and could accumulate a continuous record of age. However, recent studies presented conflicting findings on the dynamics of gastric mill ossicles during ecdysis. We herein study cuticle bands in ossicles in four species of commercially important decapod crustaceans ( Homarus gammarus, Nephrops norvegicus, Cancer pagurus and Necora puber ) in different phases of the moult cycle using dissections, light microscopy, micro-computed tomography and cryo-scanning electron microscopy. Our results demonstrate that the gastric mill is moulted and ossicles are not retained but replaced during ecdysis. It is therefore not plausible to conclude that ossicles register a lifetime growth record as annual bands and thereby provide age information. Other mechanisms for the formation of cuticle bands and their correlation to size-based age estimates need to be considered and the effect of moulting on other cuticle structures where 'annual growth bands' have been reported should be investigated urgently. Based on our results, there is no evidence for a causative link between cuticle bands and chronological age, meaning it is unreliable for determining crustacean age. Graphical abstract: Highlights: Cuticle bands in gastric mill ossicles are currently used to determine crustacean age. Bands appear in sections and synchrotron x-ray tomography of ossicles. Moulting experiments show that ossicles are not retained, but reformed at ecdysis. Histological sections confirm that ossicles are completely shed during ecdysis. Cuticle bands do not represent annually forming growth rings that indicate crustacean age.