Dual-Sex Crab of Silent Valley | 18 Mar 2026

Source: TH 

Researchers have found a rare case of gynandromorphy—a condition where an organism displays both male and female characteristics (e.g., male reproductive structures alongside female gonopores)—in a freshwater crab species, Vela carli. 

• Species & Location: Vela carli is an endemic freshwater crab species discovered within the tree holes of Silent Valley National Park in the Western Ghats. 
• Scientific Significance: This study documents the first instance of gynandromorphy in the freshwater crab family Gecarcinucidae. While known in other crustaceans, it had never before been reported in this specific family. 
  • Crustaceans are aquatic invertebrate animals belonging to the arthropod group (animals with jointed legs and an external skeleton). It includes Crabs, Lobsters, Shrimp, Prawns, etc. 

Silent Valley National Park 

• About: Silent Valley National Park, located in the Nilgiri Hills of Kerala, is a pristine tropical evergreen forest. It is renowned as one of the last undisturbed tracts of the South Western Ghats and the core of the Nilgiri Biosphere Reserve (1986), India's first biosphere reserve. 
• Geographical Feature: The Kunthipuzha River flows through the park. The name "Silent Valley" derives from the historical absence of noisy cicadas (sound-producing insects). 
• Biodiversity Hotspot: It forms part of the Western Ghats World Heritage Site (UNESCO, 2012). The park is the most significant protected habitat for the endangered Lion-tailed Macaque, its flagship species. It also harbors the Nilgiri Langur, Malabar Giant Squirrel, Nilgiri Tahr, and great Indian hornbill. 
• Historical Significance: In the 1970s, a proposed dam on the Kunthipuzha River sparked the "Save Silent Valley" movement (1973). It led to the project's abandonment and the area's declaration as a National Park in 1984.