Ultrastructural and Elemental Analysis of the Tail and Its Sensory Structures in the Red Swamp Crayfish ( Procambarus clarkii ) Using SEM and EDX Techniques

Abstract

ABSTRACT Despite the tail of the red swamp freshwater crayfish playing an important role in locomotion and environmental interactions, comprehensive studies integrating gross anatomy, ultrastructural features and elemental composition remain scarce. Therefore, the current study aimed to characterize its morphology and sensory structures using scanning electron microscopy (SEM) and SEM–Energy Dispersive X‐ray (SEM–EDX) analysis. The tail segment, situated at the end of the abdomen, comprises the telson and biramous uropods, responsible for locomotion and escape reflexes. The telson, a quadrilateral structure with an anal opening, is surrounded by uropods, which are exopod and endopod appendages articulated to the last abdominal segment. Telson and uropods display feather‐like setae that enhance swimming efficiency, with distinct specializations on their dorsal and ventral surfaces revealed by SEM observations. The ventral surface showed a smooth cranial region and a caudal folded area with longitudinal grooves and a thick transverse basal ridge bearing basket‐like projections anchoring setae. Papillae of varied shapes, each exhibiting central bulbs and sensory openings, were abundant, suggesting potential sensory specializations that may be associated with mechanosensory and chemosensory roles. The dorsal surface featured a spinated region and a papillary crest with 55–65 triangular papillae interspersed with feather‐like setae, contributing to tactile and hydrodynamic functions. SEM–EDX elemental analysis indicated a composition dominated by carbon (37.57%) and oxygen (29.96%), followed by calcium (16.67%) and nitrogen (12.54%), with trace silicon (0.21%), reflecting the chitinous and calcified nature of the exoskeleton. These findings provide detailed insights into the structural adaptations of the crayfish tail segment, revealing its intricate functionality in locomotion, sensory perception and environmental interaction.