Decapod crustacean chelipeds: an overview

Area of Science:

• Marine Biology
• Crustacean Physiology
• Evolutionary Biology

Background:

• Chelipeds (claws) are crucial appendages in decapod crustaceans, involved in feeding, defense, and social interactions.
• Sexual dimorphism in chelipeds is common, particularly in males, suggesting a role in reproductive competition.

Purpose of the Study:

• To review the structure, growth, differentiation, and function of crustacean chelipeds.
• To analyze the allometric growth patterns and sexual dimorphism in chelipeds.
• To investigate factors affecting cheliped development and regeneration.

Main Methods:

• Literature review of studies on crustacean chelipeds.
• Analysis of allometric growth patterns in relation to molting and sexual maturation.
• Examination of functional morphology and behavioral roles of differentiated chelipeds.

Main Results:

• Cheliped growth is isometric until puberty, after which males show accelerated allometric growth, leading to heterochely (unequal claws).
• Differentiated chelipeds serve distinct functions: major for agonistic encounters, minor for prey capture and grooming.
• Factors like parasitic infection and substrate conditions negatively impact cheliped growth, while regeneration incurs significant energy costs.

Conclusions:

• Cheliped morphology and growth are strongly influenced by sexual selection and environmental factors.
• The 'regeneration load' from autotomy can alter energy allocation, affecting somatic and reproductive processes.
• Incomplete exuviation involving chelipeds, as observed in Macrobrachium, highlights novel challenges in crustacean molting.