Evolution in Darkness: The Mexican Blind Cavefish

Introduction The transition from surface streams to the perpetual darkness of underwater caves has driven remarkable evolutionary changes in the Mexican blind cavefish (Astyanax mexicanus). Within the past few million years, populations migrating into caves abandoned their functional visual systems, a trait retained by their stream-dwelling counterparts. This dramatic adaptation is not unique to cavefish; troglobitic animals, including crustaceans, insects, salamanders, and spiders, have independently evolved similar traits, such as eye degeneration and heightened reliance on non-visual sensory systems.

Globally, over a hundred species of cave-dwelling fish exhibit varying degrees of blindness and other cave-specific adaptations, such as reduced pigmentation and enhanced mechanosensory abilities. The Mexican blind cavefish serves as a model organism for exploring how extreme habitats shape life through genetic, ecological, and microbiological influence