Burrow structure and distribution pattern of chestnut crab, Cardisoma carnifex (Herbst, 1796) around Parangipettai mangrove habitat, India

This study aimed to investigate the structural characteristics of burrows and other hiding places for the chestnut crab, Cardisoma carnifex, from March 2021 to April 2022 in the Parangipettai mangrove habitat, Tamil Nadu, India. Burrows were randomly selected along the northern bank of the Vellar estuary for casting. The resident crabs were captured for morphological identification, and their morphometry (carapace length [CL] and carapace width [CW]) and sex were recorded. A total of 56 burrows were selected for studying distribution patterns, and six burrows were used for morphological observations. The study found a significant positive correlation between crab carapace length, carapace width, and burrow mouth diameter. Additionally, the burrow temperature dropped significantly at greater depths, providing a suitable environment for the crabs to survive in harsh conditions.